Questions on _g_ and intelligence

[Mandrake]

PROLOG

I joined this group after reading through some of the dearths and finding that there were several people posting who were well informed and up to date on the subject of human intelligence. This is an attraction, since it is an exception to the general rule that people in discussion forums bring opinions and nothing else. I have been confronted several times by Evo with comments that were not informative, but which were apparently designed to silence me. When I reviewed her prior comments to other participants, I found that she was combative with them as well. Some of her replies to Moonbear, BV and bobf were amazingly confrontational without containing any information, logic, or analysis. I accept Evo's claims that she really knows about the things she dismisses, but I would like to ask her to tell us about those items without dismissing them, without giving just a link to something that may or may not be helpful, and without ducking the questions. I am sure she will eagerly answer questions, since she previously wrote: "Yes, BV doesn't answer to direct questions." I am sure that Evo will answer to direct questions.

Let me add that one contributor to these discussions (screen name "hitsquad") is well informed and has posted comments that are identical to what I would have written about the same issues. This person has addressed the questions pertaining to intelligence with facts that are scientifically valid and known to those who have studied the subject in depth.

QUESTIONS FOR EVO

Evo wrote: Mandrake, for every argument you have made I have already posted (in previous threads) an argument that counters it. It would be foolish to restart the endless postings, it gets nowhere.
After looking at Evo's prior comments, I was not able to find that the above statement is true. In fact, I found nothing to suggest that her prior comments addressed some of my points at all. My questions pertain to the items Evo sought to dismiss by telling me that she has previously countered each. I have not found any such counter messages. I am also familiar enough with these topics to know that the information I presented is supported by a large body of mainstream psychometric literature and by the most recognized psychometricians throughout the world. So, I will repeat the items that Evo claims she has already countered and ask her for a logical and factual explanation as to how she countered the items.

1 - Intelligence is best represented by _g_.
Do you dispute this? If so, please state your case. I am using "intelligence" to mean the cognitive function that pertains to rate of learning, problem solving, and prediction of success in intellectually demanding academic subjects and careers.

2 - Virtually all of the external validity of IQ tests comes from their _g_ loading.
Do you agree? If not, state what parts of IQ tests contribute more to their external validity and explain how you arrived at your conclusion.

3 - What we know about _g_ is that it correlates strongly with various physiological conditions: nerve conduction velocity, pH, brain volume (and more specifically we now can see that particular areas of the brain are the actors and that their volumes correlate strongly with _g_), myelination, and information intake speed.
Do you wish to dispute these well established facts? Please tell me about each of them, since each is important to intelligence and to the variances in intelligence between population groups. People can and do measure these parameters with considerable accuracy.

4 - These factors influence working memory which is now known (seen the most recent issue of the journal Intelligence) is predicted almost perfectly by _g_.
First, I want to know if you have REALLY refuted this item, as you claimed. Did you? If so, have you read the last issue of Intelligence? I get the impression that you are unfamiliar with any of the material from this peer reviewed source, so I find it very difficult to believe that you actually know about the recent study that showed the near perfect prediction of working memory from _g_ measures. Please correct me if I am wrong about this. Then tell me how you refuted this very recent finding.

5 - All of the physiological measurements are seen between the population groups that are known to differ in mean IQ scores.
How did you refute this? What is your source of information? I would like to suggest that you read all of Jensen's The _g_ Factor as a good source of information.

6 - It is possible to measure _g_ by elementary cognitive tests (which are based on response time chronometrics), with a result that correlates as well with standard IQ tests as those tests correlate with each other.
This is a simple fact. I am absolutely amazed that you refuted it. Please tell me how you disputed such a massive amount of psychometric study. As you hopefully know, this has been an area of intense psychometric research for many years and continues to be so. To further your understanding of this topic, I would like to suggest that you read all of Chris Brand's book The _g_ Factor: General Intelligence and Its Implications. Please tell me how you countered this entire field of study.

7 - It is likewise possible to determine _g_ by electroencephalography using several different techniques and with similar accuracy.
And how did you refute this? Are you familiar with the techniques used to determine _g_ from EEG amplitude measurements? Aside from those, what do you think about the string length correlation?

8 - Both of these techniques are essentially passive, not subject to practice effects, and are totally blind to all social factors.
So, you REALLY refuted this one? I find it very hard to believe that anyone would argue that electroencephalography, RT, or IT measurements are influenced by social factors. Where did you find studies that show otherwise????

[Nereid]

Mandrake, since you chose to post on an open forum, and not ask Evo via PM, I have taken the liberty of reading this, and have some questions and comments of my own; I do hope you will address them.PROLOGI joined this group after reading through some of the dearths and finding that there were several people posting who were well informed and up to date on the subject of human intelligence. This is an attraction, since it is an exception to the general rule that people in discussion forums bring opinions and nothing else. I have been confronted several times by Evo with comments that were not informative, but which were apparently designed to silence me. When I reviewed her prior comments to other participants, I found that she was combative with them as well. Some of her replies to Moonbear, BV and bobf were amazingly confrontational without containing any information, logic, or analysis. I accept Evo's claims that she really knows about the things she dismisses, but I would like to ask her to tell us about those items without dismissing them, without giving just a link to something that may or may not be helpful, and without ducking the questions. I am sure she will eagerly answer questions, since she previously wrote: "Yes, BV doesn't answer to direct questions." I am sure that Evo will answer to direct questions.

Let me add that one contributor to these discussions (screen name "hitsquad") is well informed and has posted comments that are identical to what I would have written about the same issues. This person has addressed the questions pertaining to intelligence with facts that are scientifically valid and known to those who have studied the subject in depth.

QUESTIONS FOR EVO

Evo wrote:
After looking at Evo's prior comments, I was not able to find that the above statement is true. In fact, I found nothing to suggest that her prior comments addressed some of my points at all. My questions pertain to the items Evo sought to dismiss by telling me that she has previously countered each. I have not found any such counter messages. I am also familiar enough with these topics to know that the information I presented is supported by a large body of mainstream psychometric literature and by the most recognized psychometricians throughout the world. So, I will repeat the items that Evo claims she has already countered and ask her for a logical and factual explanation as to how she countered the items.

1 - Intelligence is best represented by _g_.
Do you dispute this? If so, please state your case. I am using "intelligence" to mean the cognitive function that pertains to rate of learning, problem solving, and prediction of success in intellectually demanding academic subjects and careers.I am aware that there has been extensive study of the relationship between 'intelligence' and _g_ in the US, and possibly in Canada and the UK (e.g. Jensen); how extensive has the research been on the 'intelligence' and _g_ relationship in other parts of the world?2 - Virtually all of the external validity of IQ tests comes from their _g_ loading.
Do you agree? If not, state what parts of IQ tests contribute more to their external validity and explain how you arrived at your conclusion.same question as above.3 - What we know about _g_ is that it correlates strongly with various physiological conditions: nerve conduction velocity, pH, brain volume (and more specifically we now can see that particular areas of the brain are the actors and that their volumes correlate strongly with _g_), myelination, and information intake speed. Do you wish to dispute these well established facts? Please tell me about each of them, since each is important to intelligence and to the variances in intelligence between population groups. People can and do measure these parameters with considerable accuracy.This is quite new to me! Last time I looked, the research was quite equivocal - some studies had positive results, some negative, some mixed.4 - These factors influence working memory which is now known (seen the most recent issue of the journal Intelligence) is predicted almost perfectly by _g_.
First, I want to know if you have REALLY refuted this item, as you claimed. Did you? If so, have you read the last issue of Intelligence? I get the impression that you are unfamiliar with any of the material from this peer reviewed source, so I find it very difficult to believe that you actually know about the recent study that showed the near perfect prediction of working memory from _g_ measures. Please correct me if I am wrong about this. Then tell me how you refuted this very recent finding.

5 - All of the physiological measurements are seen between the population groups that are known to differ in mean IQ scores.
How did you refute this? What is your source of information? I would like to suggest that you read all of Jensen's The _g_ Factor as a good source of information.Would you please clarify this? IIRC, Jensen was quite explicit that his work had applicability only to the US.6 - It is possible to measure _g_ by elementary cognitive tests (which are based on response time chronometrics), with a result that correlates as well with standard IQ tests as those tests correlate with each other.
This is a simple fact. I am absolutely amazed that you refuted it. Please tell me how you disputed such a massive amount of psychometric study. As you hopefully know, this has been an area of intense psychometric research for many years and continues to be so. To further your understanding of this topic, I would like to suggest that you read all of Chris Brand's book The _g_ Factor: General Intelligence and Its Implications. Please tell me how you countered this entire field of study.

7 - It is likewise possible to determine _g_ by electroencephalography using several different techniques and with similar accuracy.
And how did you refute this? Are you familiar with the techniques used to determine _g_ from EEG amplitude measurements? Aside from those, what do you think about the string length correlation?This is also new to me - has this work been done only in the US too?8 - Both of these techniques are essentially passive, not subject to practice effects, and are totally blind to all social factors.
So, you REALLY refuted this one? I find it very hard to believe that anyone would argue that electroencephalography, RT, or IT measurements are influenced by social factors. Where did you find studies that show otherwise????IIRC, around the time of the publication of the bell curve, there was a great deal of press from critics, who included many actively working in the same field as Jensen, Brand, etc. Would you be so kind as to tell us, a) who these 'same field' critics were, b) whether they are still active in these fields, c) what these critics positions are re the 8 points above?

[Evo]

Mandrake, none of this has to do with your posts that I was referring to. I had not even read your post #36 yet, although I have also posted information on the heritability of g, if you've read my posts about it, you know that I agree on the heritability, but I do not agree that it is as high or singularly important as what you post.

Here are the posts I was referring to:

Why do you make the assumption that it was lack of intelligence and not lack of necessity?

I have previously addressed this. The clue is the mean IQ as measured in various Sub-Saharan African nations. I assume you are familiar with Lynn's book on this topic.

In the US, the Black mean IQ is below the white mean. The IQ difference between US Blacks and Whites of European descent is given by Jensen as 1.36 SD [P. 17 The _g_ Factor]

Occupation and income related to psychometric g
Helmuth Nyborg, Arthur R. Jensen
Intelligence 29 (2001) 45-55

Table 1
Percentage of Whites and Blacks within each interval (in percentiles for total sample) of g factor scores

Percentile of g factor scores
Group___10__20___30____40___50___60____70____80___ _90___100
White__5.9__6.4___9.1__11.4__7.2__12.___11.7___12. 1___9.2__14.3
Black__33.9_18.7__19.3__12.3__4.6___3.8___3.6___1. 8___1.8___0.2

The indicated percentiles represent the upper limit of each interval.

Intelligence and Social Policy: A Special Issue of the Multidisciplinary Journal INTELLIGENCE. Edited by Douglas K. Detterman. Jan/Feb 1997 (Vol 24, No.1).

The military, unlike the private sector, discriminates based on race right up front. They do not allow low intelligence recruits to enter the military. The lowest intelligence levels allowed are Army 85, Marines and Air Force 88, and the Navy 91! And what does this mean for affirmative action. Well, taking the army for example, over half of all blacks do not qualify with an average IQ of 85. All one has to ask is why is it all right for the Army to discriminate based on intelligence, but a business can't? Why the double standard? And using the same statistical data, the Navy is allowed to eliminate 65% of all blacks from consideration (that is, 65% fall below the 91 IQ cut off).
===

The Nyborg, Jensen paper I referenced shows that the Black and White racial regression lines for income versus intelligence cross at the 40th percentile. Above that point, Black income exceeds that of Whites. The authors note: "However, in the present study sample the overall average income of Bs is only 77% that of Ws, given that in the total study sample 84.2% of Bs are below the 40th percentile of g scores compared to 32.8% of Ws, and 67.2% of Ws are above the 40th percentile compared to 15.8% of Bs."

For ALL percentiles, the job status index for Blacks exceeds that for Whites (index plotted against _g_ percentiles) with the gap increasing linearly as intelligence increases.

These rather recent observations are consistent with similar observations reported in The Bell Curve.

I have repeated the scientific findings of the past 100 years, which have consistently shown that the mean IQs of various population groups are not identical. Is that racist? If you think so, I would like to suggest that you have no idea of what constitutes racism. For examples of real racism, please study the history of Japan and Germany at the time of WW2.

As for population groups, the highest mean is found among Ashkenazi Jews.
After that, in order of decreasing means, we have Asians, whites of European descent, Hispanics, US blacks, and Sub-Saharan Africans, to name some of the prominent groups. It has been over 75 years since Spearman's Hypothesis was recorded; since that time there has been much effort expended to disprove it, but the result has been to prove the hypothesis beyond doubt.

Anyone who believes that IQ tests are biased against blacks should take the time to read Jensen's Bias in Mental Testing. This massive book examines IQ tests in detail and shows under what circumstances they are biased and under what circumstances they are not. Standard IQ tests are not biased against blacks. It is well documented that those tests are slightly biased in favor of blacks, by virtue of their external validity. That is, blacks perform less well than other groups in colleges and jobs as compared to individuals in those other groups with identical IQ scores.

The findings of Bias in Mental Testing were rejected by liberals on the basis of their non-scientific "feelings" as to how the results should have turned out. As a result they demanded and got the National Academy of Sciences to review the findings. The result was that the National Academy of Sciences found that there was (as Jensen had meticulously reported) no bias in IQ tests that caused lower scores for blacks. [This information is widely reported. One source is P. 83 of Miele (2002) - Intelligence, Race, and Genetics: Conversations with Arthur R. Jensen]

As I said, I have previously countered these topics and do not wish to do it over and over. I do not have time to sort through hundreds of posts.

Here is one that I posted, just sort of addresses all of the above.

http://www.raceandhistory.com/historicalviews/ukwise.htm

[Mandrake]

Mandrake, since you chose to post on an open forum, and not ask Evo via PM, I have taken the liberty of reading this, and have some questions and comments of my own; I do hope you will address them.
Thank you for replying. I posted the thread so that all here could enter into discussions of the items in question. I will be happy to comment on your questions and observations. This may take me a while, so I will post the detailed replies in a separate message.

[Mandrake]

I do hope you will address them.
Okay, here goes:

I am aware that there has been extensive study of the relationship between 'intelligence' and _g_ in the US, and possibly in Canada and the UK (e.g. Jensen); how extensive has the research been on the 'intelligence' and _g_ relationship in other parts of the world?

Psychometrics is an international science. It has been advanced by scientists from many countries. As an illustration I will present a few examples below:
Eysenck -- Berlin (later London)
Spearman -- England
Stern -- Germany
Deary -- Scotland (will deliver the keynote address at the next conference of the International Society of Intelligence Research {ISIR} -- in honor of the 100th adversary of Spearman's discovery of _g_)
Lynn -- England
Plomin -- England
Burt -- England
J. Hunt -- England
Rushton -- Canada
Vernon -- Canada
Brand -- England
Binet -- France
Galton -- England
Barrett -- New Zealand
Weiss -- Germany (formerly East Germany)
Mary Smith -- Australia (not well known, but referenced by Jensen for her work in eye blink response)

Those are only a few of the well known scientists. If you scan through the papers in Intelligence you will find sources from many countries. For example, I have V32 #3 open right now; it contains contributions from London, Ireland, Spain, United States, Canada, Poland, and Scotland. That is only one issue!

2 - Virtually all of the external validity of IQ tests comes from their _g_ loading.
same question as above.

Same answer. The literature for this field is international. The external validity of IQ tests is basic to the field of study and has been reported internationally as it has been studied for various specific applications. Anyone reading the stream of papers over the years will notice that there is a lot of material from the US, but it is far from the only source.

3 - What we know about _g_ is that it correlates strongly with various physiological conditions: nerve conduction velocity, pH, brain volume (and more specifically we now can see that particular areas of the brain are the actors and that their volumes correlate strongly with _g_), myelination, and information intake speed.

This is quite new to me! Last time I looked, the research was quite equivocal - some studies had positive results, some negative, some mixed.

I can only suggest that you keep looking. Have you read Jensen, A. R. (1998). The g factor: The science of mental ability? It is one of the best references available for broad coverage of the topic of psychometrics. Of these, the brain volume subject has received particularly prolonged study. The development of fMIR technology has enabled researchers to identify and measure the volumes of specific parts of the brain and to correlate them to _g_ (even group factors show up as specific locations). The research was done by Richard Haier and was presented at the 2003 ISIR conference. This is cutting edge material.

Myelination is central to the neural noise model developed by Edward Miller and remains robust a decade after he first wrote about it. Nerve conduction velocity seems to explain the variance in RT measured by many researchers and is presumed to be related to the volatile nature of working memory. RT measurements show that the variance in RT correlates independently to IQ. This cannot be explained by NCV, but does fit Miller's explanation based on neural noise. It appears that both factors are operating and are independent.

Information intake speed has continued to be reported regularly in Intelligence. Much of the present day research is focused on inspection time, instead of response time, but response time remains central to the understanding of chronometrics. The quantity of papers on this subject is so large that there is no one researcher to identify as the most important.

5 - All of the physiological measurements are seen between the population groups that are known to differ in mean IQ scores.

Would you please clarify this? IIRC, Jensen was quite explicit that his work had applicability only to the US.

The US has multiple population groups, with known IQ differences. For example, there are Ashkenazi Jews, Whites of European ancestry, American Indians, Hispanics, and Blacks. The physiological differences in question have been measured by many different researchers. The point of my comment is that these differences appear as group differences and correlate with _g_ independently of the group identity. For example, that means that the mean brain volume differences between US blacks and US whites are as expected, given the differences in mean IQs for these two groups. Chronometric measurements similarly vary between groups in proportion to the observed differences in _g_ between the groups.

7 - It is likewise possible to determine _g_ by electroencephalography using several different techniques and with similar accuracy.

This is also new to me - has this work been done only in the US too?

Some of the work was done by Paul Barrett of New Zealand. The strongest correlations for neural adaptability (NA) were found by E. W. P. Schafer. I don't know where his laboratory is located. His NA index correlates at about +.82 with IQ, which is better than many standard IQ tests correlate with each other and equal to the best test to test correlations.

8 - Both of these techniques are essentially passive, not subject to practice effects, and are totally blind to all social factors.
So, you REALLY refuted this one? I find it very hard to believe that anyone would argue that electroencephalography, RT, or IT measurements are influenced by social factors. Where did you find studies that show otherwise????

IIRC, around the time of the publication of the bell curve, there was a great deal of press from critics, who included many actively working in the same field as Jensen, Brand, etc. Would you be so kind as to tell us, a) who these 'same field' critics were, b) whether they are still active in these fields, c) what these critics positions are re the 8 points above?

I am confused by your question. What is your reference to "same field" about? I didn't mention it in item 8. Was your question related to another point? The critics of The Bell Curve were overwhelmingly journalists who had no prior knowledge of the topic, even though Seligman's book (A Question of Intelligence) had been published about two years earlier and covered most of the same material. Besides that, anyone reading the scientific literature knew that the subjects discussed in The Bell Curve were old hat and some were known 75 or more years ago.

There were a handful of people who claimed credentials who also were critical of The Bell Curve. Of these, some were totally out of their field (Gould, for example) and some were simply the usual outliers that are found in any scientific field. They either didn't "get it" or they found that there was a real market for selling their opposition to people who wanted to hear anti-science ranting. Gardner is one of those. When The Bell Curve came out, I immediately bought it and read every word of it. I was amazed to see that it contained very little that was not already published (that "little" was the analysis of the National Longitudinal Study of Youth data set). Shortly, the ignorant press began to attack The Bell Curve and this infuriated Linda Gottfredson. She is incapable of sitting still when someone is publishing scientifically corrupt material (recently she completely dissected and destroyed Sternberg's Triarchic theory). She wrote the letter to the Wall Street Journal that someone here posted in another thread. She intentionally wrote it as an understatement because she wanted to get it signed and printed without delay. It appeared with the 52 signatures you have seen in the other thread. The simple fact is that no credible psychometricians object to the salient points covered in The Bell Curve. Murray has commented that the discussion that was hot after the book came out does not exist today because it is understood.

[BlackVision]

"Yes, BV doesn't answer to direct questions."
LOL. Now there is a joke if I ever saw one. I always directly answer questions. Evo on the other hand is the type that likes to play dodgeball. You should of seen the way she acted with my simple question "Does one's ability to be in higher SES improve with higher intelligence?" I asked her this 20 times, never got an answer.

[BlackVision]

As I said, I have previously countered these topics
You have never done such a thing. Although I'm sure you wish you had.

[NoahAfrican]

Please, can someone tell me whether or not we have reached the end of science in regards to the brain and the total cause and effects of human actions, performance and behavior? Has it been true in history that what was once state of the science understanding was later refuted as humans gained more knowledge of the phenomenon being hypothesized about?

It is interesting why Mandrak accepts such hypothesis in light of the fact that we have not reached the end of knowledge in regard to how the brain works. At base, these hypothesis are merely deduced or assumed from what humans have learned about the workings of the brain. Furthermore, given that there exist counter hypothesis, by equally accredited people in the field, how does people like Mandrak determine who to believe, when he has not the ability to do the research for himself?

Again, there is an obvious bias in what Mandrak chooses to believe, because he simply dismisses the counter hypothesis without elaborating on what discredit’s their authors. It is tantamount to the people who choose to watch FOX (Faux) news, instead of CNN or PBS news. They already have a preconceived notion of what they see as the truth, which happens to be represented by a conservative ideology, thus they gravity towards the conservative conclusion with they already hold, while attempting to discredit the other ideologies conclusions and opinions.

Again, what one believes without the ability to independently observe or reproduce is a choice based upon preexisting notions or beliefs.

[Evo]

You have never done such a thing. Although I'm sure you wish you had.Yes, I posted counter opinions.

BV, you've not answered many direct questions.

[BlackVision]

BV, you've not answered many direct questions.
I think you mean you. Like how you ignored my question once again.

I always answer your questions which apparently you always shrug off because it's not something you want to hear.

[Moonbear]

When I reviewed her prior comments to other participants, I found that she was combative with them as well. Some of her replies to Moonbear, BV and bobf were amazingly confrontational without containing any information, logic, or analysis.

:confused: Evo's replies to me were confrontational? I've never gotten that impression. Perhaps it's all a matter of perspective?

I have some more comments regarding the substance of one of your other replies here...the stuff on fMRI. But, it's nearly 1:30 AM and I only got home from the lab about a half hour ago (just online while winding down before bed), so I'm not likely to provide a coherent argument on something that requires thinking right now. Besides, I had to go look up some new stuff and I'm too tired to absorb it all just yet. You forced me to catch up on recent findings with MRI, which is good. Though, I think some of what you wrote isn't completely accurate with regard to measuring volumes of parts of the brain, but that's the part I'm too tired to answer thoroughly just yet. I want to check a little more literature before I respond in case there is a new method that I'm not yet aware of...unless you already know if that study you mentioned presented at a conference is specifically looking at white matter volumes (I spotted an article tonight addressing white matter in developmental delay, so that might be related)?

And, will somebody please define "g" for me? I've seen a lot of quotes around here referring to some book by Jensen throwing around the term "g", but I really don't have a full grasp of what this is, and from the quotes I've seen, I'm not really enthusiastic about going and getting a copy of the book to find out.

[hitssquad]

will somebody please define "g" for me?g is the source of broadest common variance in any given matrix of mental ability tests. Factor-loadings (including g-loadings) of mental tests are determined by factor analyzing the results of tests adminstered to multiple subjects. (In terms of the most widely used IQ tests, the vocabulary subtests tend to be revealed by factor analysis as having the highest g-loadings of any subtest.)

Since g is the most-general factor of mental-ability tests, it is the factor that is most predictive of general outcomes. Relatively narrow outcomes tend to be better predicted by narrower ability factors such as those that have been borrowed by Howard Gardner to form his list of "multiple intelligences."



I've seen a lot of quotes around here referring to some book by Jensen throwing around the term "g", but I really don't have a full grasp of what this is, and from the quotes I've seen, I'm not really enthusiastic about going and getting a copy of the book to find out.It is called The g Factor (http://www.questia.com/PM.qst?a=o&d=24373874) (1998), and it is co-published online by the electronic library Questia ($120 annual subscription). Arthur Jensen is the world's greatest living authority on the g factor. Author of more than 400 peer-reviewed papers, he is one of the most-frequently cited scientists of all time, and all of his most important books (and his 1969 Harvard Educational Review article "How Much Can We Boost IQ and Scholastic Achievement?") are listed as citation classics by the Institute for Scientific Information (ISI). He earned his post-doctorate under Hans Eysenck at the University of London and rose to the unusually-high rank of supergrade professor while teaching Educational Psychology at UC Berkeley.

[Evo]

:confused: Evo's replies to me were confrontational? I've never gotten that impression. Perhaps it's all a matter of perspective? Mandrake's a bit confused on some things. :wink:

[Mandrake]

:confused: Evo's replies to me were confrontational? I've never gotten that impression. Perhaps it's all a matter of perspective?
No, I picked up your name from the remainder of a post in which Evo was attacking other people, but not you. I apologize for including your name on the list.

[Mandrake]

Originally Posted by Evo
BV, you've not answered many direct questions.

I think you mean you. Like how you ignored my question once again.

I always answer your questions which apparently you always shrug off because it's not something you want to hear.
I pointed out in another thread that Evo also ducked the simple questions I posed. For example, I asked her if she had read The Bell Curve. I asked because she was critical and dismissive of it. You would think that, if she had read the book, she would recall doing so and that if she had not, she might recall that as well. She just ducked.

[Nereid]

Thanks Mandrake.

Some more equiries (I hope you don't mind)Psychometrics is an international science. It has been advanced by scientists from many countries. As an illustration I will present a few examples below:
Eysenck -- Berlin (later London)
Spearman -- England
Stern -- Germany
Deary -- Scotland (will deliver the keynote address at the next conference of the International Society of Intelligence Research {ISIR} -- in honor of the 100th adversary of Spearman's discovery of _g_)
Lynn -- England
Plomin -- England
Burt -- England
J. Hunt -- England
Rushton -- Canada
Vernon -- Canada
Brand -- England
Binet -- France
Galton -- England
Barrett -- New Zealand
Weiss -- Germany (formerly East Germany)
Mary Smith -- Australia (not well known, but referenced by Jensen for her work in eye blink response)Many of these names I don't recognise, but aren't Eysenck, Spearman, Burt, Binet, and Dalton all long since gone? Perhaps I simply don't understand 'psychometrics' - I had the impression it would be a very new field, something that really only began after objective study of the brain could start. How does it relate to other branches of neuroscience?Same answer. The literature for this field is international. The external validity of IQ tests is basic to the field of study and has been reported internationally as it has been studied for various specific applications. Anyone reading the stream of papers over the years will notice that there is a lot of material from the US, but it is far from the only source.Roughly speaking, what proportion of the papers are from scientists from economies of the developing world?I can only suggest that you keep looking. Have you read Jensen, A. R. (1998). The g factor: The science of mental ability? It is one of the best references available for broad coverage of the topic of psychometrics. Of these, the brain volume subject has received particularly prolonged study. The development of fMIR technology has enabled researchers to identify and measure the volumes of specific parts of the brain and to correlate them to _g_ (even group factors show up as specific locations). The research was done by Richard Haier and was presented at the 2003 ISIR conference. This is cutting edge material.

Myelination is central to the neural noise model developed by Edward Miller and remains robust a decade after he first wrote about it. Nerve conduction velocity seems to explain the variance in RT measured by many researchers and is presumed to be related to the volatile nature of working memory. RT measurements show that the variance in RT correlates independently to IQ. This cannot be explained by NCV, but does fit Miller's explanation based on neural noise. It appears that both factors are operating and are independent.

Information intake speed has continued to be reported regularly in Intelligence. Much of the present day research is focused on inspection time, instead of response time, but response time remains central to the understanding of chronometrics. The quantity of papers on this subject is so large that there is no one researcher to identify as the most important.I see Moonbear has noticed this; I'll dig up the references I remember reading which discussed the limitations of this research.

In the meantime, can you point me to a paper describing the commonly accepted experimental protocols? I'm particularly interested in subject selection and the extent to which double-blind protocols are employed.The US has multiple population groups, with known IQ differences. For example, there are Ashkenazi Jews, Whites of European ancestry, American Indians, Hispanics, and Blacks. The physiological differences in question have been measured by many different researchers. The point of my comment is that these differences appear as group differences and correlate with _g_ independently of the group identity. For example, that means that the mean brain volume differences between US blacks and US whites are as expected, given the differences in mean IQs for these two groups. Chronometric measurements similarly vary between groups in proportion to the observed differences in _g_ between the groups. Hmm. I'm still interested in knowing whether Jensen (and others) have been clear that their work has validity only in the geographical region in which it was conducted, or whether it can be used globally (and if so, why).I am confused by your question. What is your reference to "same field" about? I didn't mention it in item 8. Was your question related to another point? The critics of The Bell Curve were overwhelmingly journalists who had no prior knowledge of the topic, even though Seligman's book (A Question of Intelligence) had been published about two years earlier and covered most of the same material. Besides that, anyone reading the scientific literature knew that the subjects discussed in The Bell Curve were old hat and some were known 75 or more years ago.

There were a handful of people who claimed credentials who also were critical of The Bell Curve. Of these, some were totally out of their field (Gould, for example) and some were simply the usual outliers that are found in any scientific field. They either didn't "get it" or they found that there was a real market for selling their opposition to people who wanted to hear anti-science ranting. Gardner is one of those. When The Bell Curve came out, I immediately bought it and read every word of it. I was amazed to see that it contained very little that was not already published (that "little" was the analysis of the National Longitudinal Study of Youth data set). Shortly, the ignorant press began to attack The Bell Curve and this infuriated Linda Gottfredson. She is incapable of sitting still when someone is publishing scientifically corrupt material (recently she completely dissected and destroyed Sternberg's Triarchic theory). She wrote the letter to the Wall Street Journal that someone here posted in another thread. She intentionally wrote it as an understatement because she wanted to get it signed and printed without delay. It appeared with the 52 signatures you have seen in the other thread. The simple fact is that no credible psychometricians object to the salient points covered in The Bell Curve. Murray has commented that the discussion that was hot after the book came out does not exist today because it is understood.Sorry that I wasn't clear.

Let me give you an analogy first (like all analogies, it should not be extended beyond the scope for which I intend it): in astrophysics/cosmology literature you will see reference to 'dark energy' and to 'dark matter'. In the 'concordance model', the observations which point to the existence of both dark energy and dark matter are well accounted for (there are formal statistical measures of the goodness of fit). If one wanted to, one could probably prepare a statement on cosmology like the WSJ one (1994? 1995?) signed by approx the same number of active astronomers, astrophysicists, etc. However, there would be quite a few who wouldn't sign such a statement, and not just because they would feel such things are pointless (even though they may be staunch advocates of the concordance model). Such folk would include those who felt that the observational data was not good enough to conclude 'there exists dark matter or (especially) dark energy'; there would be those who have no trouble with the data pointing to something like DM or DE, but who view the concordance model as flawed or suspect for entirely other reasons; and so on.

So my question is two-fold:
1) are there serious critics of psychometrics? If so, what are their views - what are the bases of their critiques?
2) among those who are active in the field of psychometrics, what divergence of opinion is there? For example, how widely accepted are the conclusions of those who've done fMRI work?

Finally, if I have understood you correctly, it is now possible to determine the IQ of a person (or their g) purely from neurophysiology tests such as fMRI (with the appropriate double blind protocols of course) - yes? no? something else??

[Evo]

I pointed out in another thread that Evo also ducked the simple questions I posed. For example, I asked her if she had read The Bell Curve. I asked because she was critical and dismissive of it. You would think that, if she had read the book, she would recall doing so and that if she had not, she might recall that as well. She just ducked.As I have pointed out in other threads, Mandrake, you have made a large number of false accusations and one outright lie. I suggest you stop.

Here is a good overview of the many posts on the Bell Curve and the people involved that I have been posting for some time. This kind of evidence cannot be dismissed.

The science behind The Bell Curve has been denounced by both the American Psychological Association and the Human Genome Project

"The scientific basis of The Bell Curve is fraudulent." (1)

With those words, the American Psychological Association denounced The Bell Curve, the controversial book that claims that blacks generally have IQs 15 points lower than whites. The authors assert that because IQ is mostly genetic and unchangeable, programs promoting equality (affirmative action, welfare, Head Start, etc.) are a waste of money. For those unfamiliar with the American Psychological Association, it is the largest scientific and professional organization representing psychology in the United States, and includes over 142,000 members.

http://www.huppi.com/kangaroo/L-bellcurvescience.htm

[hitssquad]

Perhaps I simply don't understand 'psychometrics'Psychometrics is the use of scientific instruments to gather quantitative psychological data. An IQ test would be an example of a psychometric instrument — despite its reliance on voluntary responses from test subjects. Therefore, psychometrics does not merely refer to the use of instruments — such as the more-recently-invented evoked-potentials tests — that make use of involuntary resonses from test subjects.


M-W Unabridged definition of psychometrics:

Etymology: International Scientific Vocabulary
1 : relating to the measurement of mental or subjective data
2 : relating to or being a mental test or psychological method whose results are expressed quantitatively rather than qualitatively

[Mandrake]

Thanks Mandrake.

Some more equiries (I hope you don't mind)Many of these names I don't recognise, but aren't Eysenck, Spearman, Burt, Binet, and Dalton all long since gone?
Dalton was not on the list. The other four are dead. Eysenck died in October 1997, which doesn't seem that long ago to me. I gave you a list of mostly important people who are from other countries over the time period that applies to this field of science (roughly 100 years).

Perhaps I simply don't understand 'psychometrics' - I had the impression it would be a very new field, something that really only began after objective study of the brain could start.
Psychometrics began with mental testing. Spearman developed factor analysis and discovered _g_ in 1904.

How does it relate to other branches of neuroscience?
Much of the research in psychometrics is now in the area of neuroscience and genetics. Psychometrics has become a much more laboratory field in recent years.

Roughly speaking, what proportion of the papers are from scientists from economies of the developing world?
Roughly the same proportion that you find in such other scientific fields as super conductivity, nuclear fission, space exploration, brain surgery, metal matrix composites, etc.

In the meantime, can you point me to a paper describing the commonly accepted experimental protocols? I'm particularly interested in subject selection and the extent to which double-blind protocols are employed.
I suggest that you simply pick up and read a stack of the journal Intelligence. Each issue is filled with up to date research papers, and each explains its experimental procedures in the detail that you would expect for a peer reviewed source. The procedures used for measuring glucose uptake are quite different from the procedures used to measure working memory chunks.

Hmm. I'm still interested in knowing whether Jensen (and others) have been clear that their work has validity only in the geographical region in which it was conducted, or whether it can be used globally (and if so, why).Sorry that I wasn't clear.
Psychometrics is focused on mental performance, not geography. One large area of investigation has been the differences between population groups. I have never seen any indication that geography has been identified as a variable. There are studies in which Asian populations were tested in Asia and compared to first generation Asians who were born to the same population group, but in the US. The groups tested identically. As I recall, this was discussed in The Bell Curve, but it is always worth checking The _g_ Factor as well.

So my question is two-fold:
1) are there serious critics of psychometrics? If so, what are their views - what are the bases of their critiques?
Let me ask you to consider the question as applied to other fields. Are there serious critics of laser research? Of carbon composites? Of organic chemistry? Of space exploration? The answers are that when one gets down to individual issues, there will be some in which there are debates among informed people as to exactly what is happening. If the issue is something that has been resolved, the critics are most likely to be crackpots. At this point, the only people doubting the 100 year study of the variance in intelligence are crackpots. Likewise there are no informed people still arguing that population groups have identical mean IQs. Those issues were argued years ago and are now history.

2) among those who are active in the field of psychometrics, what divergence of opinion is there? For example, how widely accepted are the conclusions of those who've done fMRI work?
The answer is much the same. There is divergence on some issues and not on others. There are also a few people who are following their own lines by creating different models of how the brain works. Some of those will ultimately gain strength and some will evaporate. Ask yourself if there is universal agreement on all aspects of the Big Bang and you will get to a similar point.

Finally, if I have understood you correctly, it is now possible to determine the IQ of a person (or their g) purely from neurophysiology tests such as fMRI (with the appropriate double blind protocols of course) - yes? no? something else??
Not yet with fMIR. There are three ways to determine _g_: IQ tests, followed by an extraction of _g_; chronometric measurements; and electroencephalography measurements. With each of these there are various approaches that give reasonable results. There are no diverse tests that correlate perfectly.

[Nereid]

Psychometrics is the use of scientific instruments to gather quantitative psychological data. An IQ test would be an example of a psychometric instrument — despite its reliance on voluntary responses from test subjects. Therefore, psychometrics does not merely refer to the use of instruments — such as the more-recently-invented evoked-potentials tests — that make use of involuntary resonses from test subjects.


M-W Unabridged definition of psychometrics:

Etymology: International Scientific Vocabulary
1 : relating to the measurement of mental or subjective data
2 : relating to or being a mental test or psychological method whose results are expressed quantitatively rather than qualitativelyThanks hitssquad.

What's the relationship between psychometrics and neuroscience then? When does psychometrics become something else (e.g. is it psychometrics when you study a person's eye movements while reading? how about a quantitative study of moods, of synesthesia, of sleep?

[Nereid]

Dalton was not on the list. The other four are dead. Eysenck died in October 1997, which doesn't seem that long ago to me. I gave you a list of mostly important people who are from other countries over the time period that applies to this field of science (roughly 100 years).My typo, I meant Galton.
Psychometrics began with mental testing. Spearman developed factor analysis and discovered _g_ in 1904.

Much of the research in psychometrics is now in the area of neuroscience and genetics. Psychometrics has become a much more laboratory field in recent years.What is its scope today? (I answered hitssquad before I saw your post; I'm quite curious as to the boundaries - e.g. is it psychometrics when my doctor uses an electronic stopwatch and ruler to measure my knee reflexes? since taste is subjective - and mental - and can be measured quantitatively I'm sure, is the study of taste a branch of psychometrics?)I suggest that you simply pick up and read a stack of the journal Intelligence. Each issue is filled with up to date research papers, and each explains its experimental procedures in the detail that you would expect for a peer reviewed source. The procedures used for measuring glucose uptake are quite different from the procedures used to measure working memory chunks.I'll see if my local library has a copy. Why is it called 'Intelligence'? From the definition, it would seem that intelligence would be a very small part of the field. :confused: I'd've thought that, since you're working with humans and their mental states, double blind protocols would be even more important in psychometrics than in studies of glucose uptake! Surely the psychometric equivalent of the placebo effect (or the 'white coat effect') would be huge :eek:Psychometrics is focused on mental performance, not geography. One large area of investigation has been the differences between population groups. I have never seen any indication that geography has been identified as a variable. There are studies in which Asian populations were tested in Asia and compared to first generation Asians who were born to the same population group, but in the US. The groups tested identically.Wow! That's truly staggering!! After all, plenty of studies have shown that there are quite significant physiological differences between first generation migrants and their stay-at-home peers, esp the effects of diet (e.g. incidence of heart disease, the switching on - or off - of various enzyme reaction trigger genes, and much more). Too, IIRC, the effects of the childhood environment and pre-birth environments can be enormous - just look at the crack babies, and the well-known 'siblings' effects. The findings you just reported would seem, prima facie, to fly in the face of a vast amount of medical research.Let me ask you to consider the question as applied to other fields. Are there serious critics of laser research? Of carbon composites? Of organic chemistry? Of space exploration? The answers are that when one gets down to individual issues, there will be some in which there are debates among informed people as to exactly what is happening. If the issue is something that has been resolved, the critics are most likely to be crackpots.My comment was based on my assumption that it was a completely new field; in any new field, there is a period in which critics - rightly - question whether it is really a science. Look at astrobiology, for example.At this point, the only people doubting the 100 year study of the variance in intelligence are crackpots. Likewise there are no informed people still arguing that population groups have identical mean IQs. Those issues were argued years ago and are now history.Hmm, do you mean in the last ten years? The link which Evo posted has some pretty weighty pronouncements, e.g. "What is intelligence and can it be measured? These questions have fueled a continuing debate about whether intelligence is inherited, acquired, environmental, or a combination of these and other factors. In a field where so many issues are unresolved and so many questions unanswered, the confident tone that has characterized most of the debate on these topics is clearly out of place." Of course, this is in reference to the bell curve, and was written in 1995. The 1996 letter to Science by the members of the HGP was also pretty damning - surely they're not crackpots?The answer is much the same. There is divergence on some issues and not on others. There are also a few people who are following their own lines by creating different models of how the brain works. Some of those will ultimately gain strength and some will evaporate.Is there now a biological theory of intelligence? Or are there competing theories?Not yet with fMIR. There are three ways to determine _g_: IQ tests, followed by an extraction of _g_; chronometric measurements; and electroencephalography measurements. With each of these there are various approaches that give reasonable results. There are no diverse tests that correlate perfectly.What are 'chronometric measurements'? What is the typical experimental error in _g_ from these? Ditto, for EEG measurements? How are the 'zero point' and scale of _g_ defined?

[Mandrake]

Nereid:
My typo, I meant Galton.
FWIW, one of the many very important books by Jensen, Bias in Mental Testing, was dedicated to Galton, Binet, and Spearman. Galton was so far ahead of his time that he had a strong interest in the inheritance of mental ability and wrote the book HEREDITARY GENIUS in 1896. Amazing!

Much of the research in psychometrics is now in the area of neuroscience and genetics. Psychometrics has become a much more laboratory field in recent years.

Before going further, I want to tell you that I appreciate your thoughtful and well stated comments and questions. It is a pleasure to converse with someone who is alert and not looking for a fight.

What is its scope today? (I answered hitssquad before I saw your post; I'm quite curious as to the boundaries - e.g. is it psychometrics when my doctor uses an electronic stopwatch and ruler to measure my knee reflexes? since taste is subjective - and mental - and can be measured quantitatively I'm sure, is the study of taste a branch of psychometrics?)
Psychometrics is about intelligence. It started with the development of mental tests, which became IQ tests. Psychometrics seeks to measure intelligence, to find its correlates, and to understand the root causes for the differences that are found. Essentially all of the work in psychometrics now falls in the category of "differential psychometrics." It is based on experimental and correlational methods.

It turns out that the variance in intelligence correlates with a very wide range of other things, such as the ability to differentiate pitch, myopia, the complexity of wave from from an EEG, brain response time to external stimuli, the energy consumption of the brain, pH, and some other factors, many of which are probably extrinsic, such as good looks, eye color, leg length, lung capacity, grip strength, etc.

I suggest that you simply pick up and read a stack of the journal Intelligence. Each issue is filled with up to date research papers, and each explains its experimental procedures in the detail that you would expect for a peer reviewed source. The procedures used for measuring glucose uptake are quite different from the procedures used to measure working memory chunks.

I'll see if my local library has a copy.

If not, a good university should have copies. I should add that INTELLIGENCE is THE journal of psychometrics. Although there are occasionally good papers presented in other places, the real focus of this scientific speciality is in the journal of the International Society for Intelligence Research. This small group includes almost every big name psychometrician alive and a few (me for example) who are groupies. ;-)

Why is it called 'Intelligence'? From the definition, it would seem that intelligence would be a very small part of the field.
"Intelligence" is the entire field. If it does not relate to intelligence, it is not part of psychometrics.

Psychometrics is focused on mental performance, not geography. One large area of investigation has been the differences between population groups. I have never seen any indication that geography has been identified as a variable. There are studies in which Asian populations were tested in Asia and compared to first generation Asians who were born to the same population group, but in the US. The groups tested identically.

Wow! That's truly staggering!! After all, plenty of studies have shown that there are quite significant physiological differences between first generation migrants and their stay-at-home peers, esp the effects of diet (e.g. incidence of heart disease, the switching on - or off - of various enzyme reaction trigger genes, and much more).
Intelligence is determined by extrinsic and intrinsic genetic factors and by micro environmental factors. The micro environmental factors are real, but contribute relatively little to the total. These environmental effects are much more observable in childhood than later in life. It is also likely that some macro environmental effects can be seen in childhood, but these vanish by adulthood. You can also find IQ tests given to whites who live in Africa and you will see that those match their peer groups in Europe. For example, there are studies of intelligence in all of South Africa. The white population there is composed of Dutch and English stock. People don't suddenly become smarter or dumber because they move to another country.

More to the point, I have mentioned the very significant findings of the physiological correlations to intelligence. These hold not only within groups, but also between groups (including population groups). For example, brain volume has been studied by every means known (weighing brains from corpses, measuring head size, measuring skull volume, then by MRI mapping, etc.). The reason these studies have been continued is that the correlation between brain volume and intelligence is robust. It doesn't matter where the subjects lived, or what their race, the results correlate the same. Likewise the measurements of response time are indifferent to social or racial factors. Response time measurements, as applied to elementary cognitive tasks, are _g_ loaded in the range of about .2 to .3 or so, but their variances are additative. If you run an appropriate battery of tests, the sum of the variances produces an excellent measurement of _g_. This is basically the same as what happens in IQ test items. Each item is very lightly _g_ loaded, but a range of test items can be combined to yield a good final IQ score, from which _g_ can be extracted.

Too, IIRC, the effects of the childhood environment and pre-birth environments can be enormous - just look at the crack babies, and the well-known 'siblings' effects.

In science, one compares items from A that are equal to items from B, except for one variable. It would be inappropriate to compare crack babies from one country to normal babies from another. The big name psychometricians are very well educated scientists and have conducted their research quite carefully.

The findings you just reported would seem, prima facie, to fly in the face of a vast amount of medical research.
No. The idea is to allow only one variable at a time. I should add that some intelligence related papers have been written by physicians and most are full of errors that are traceable to the ignorance of psychometrics by the medical people.

My comment was based on my assumption that it was a completely new field; in any new field, there is a period in which critics - rightly - question whether it is really a science. Look at astrobiology, for example.

Psychometrics is not new, as you now know. It has benefitted from the same transformation that affected biology, namely the movement from limited laboratory research to the opposite.

At this point, the only people doubting the 100 year study of the variance in intelligence are crackpots. Likewise there are no informed people still arguing that population groups have identical mean IQs. Those issues were argued years ago and are now history.

[Mandrake]

Hmm, do you mean in the last ten years? The link which Evo posted has some pretty weighty pronouncements,

Do you mean her "kangaroo" link? I had seen that one before. It was put up by Steve Kangas, who says on his page that he is a student seeking a degree in Russian Studies. Is that a good source of scientific information? He identifies himself as an ultra-liberal and obviously has a very strong political agenda. If you look at his references, you will see that they include these scientific sources:
The San Francisco Chronicle
People For The American Way
USA Today
Boston Globe
The New York Times Magazine
Discovery Journal
The Nation,
Rolling Stone
Newsday
Newsweek.

e.g. "What is intelligence and can it be measured? These questions have fueled a continuing debate about whether intelligence is inherited, acquired, environmental, or a combination of these and other factors. In a field where so many issues are unresolved and so many questions unanswered, the confident tone that has characterized most of the debate on these topics is clearly out of place." Of course, this is in reference to the bell curve, and was written in 1995. The 1996 letter to Science by the members of the HGP was also pretty damning - surely they're not crackpots?

I didn't see the letter to Science. Can you provide me with the link? Do you have the names and job positions of the people who wrote the letter? APA is not a group of psychometricians, it is a group of psychologists, a few of whom may be psychometricians. When a letter goes out, it is not the joint finding of the entire membership nor is it the joint finding of those members who are actually qualified to make a judgement. If you want to read a real report of real scholars, who were polled and asked to respond only when they believed that they were qualified to answer, look up and read the Snyderman-Rothman report.

Psychological Reports, 1998, 82, 1346-1374. ©Psychological Reports 1998

Never cited by critics of The Bell Curve, however, are the findings of Snyderman and Rothman, who surveyed 1,020 experts in behavioral genetics and psychometrics in the 1980s. These findings, which were initially published in the American Psychologist (Snyderman & Rothman, 1987) and later in a book, The IQ Controversy: The Media and Public Policy (Snyderman & Rothman, 1988), were that 53% agreed that there is a consensus among psychologists and educators as to the kind of behaviors labeled as "intelligent" (p. 55); 60% agreed that IQ is an important determinant of socio-economic status (p. 66); 58% agreed that intelligence is a general ability rather than a multiplicity of separate faculties (p. 71); a majority of those responding agreed that there is a substantial within-group heritability for intelligence (p. 95); and a plurality agreed that part of the difference between black and white groups in average IQ is genetic in origin (p. 128) (Snyderman & Rothman, 1988).

My guess is that a repeat of this study would result in overwhelming agreements on the points listed. Most of these issues are dead, and yes, they died after publication of The Bell Curve. Again, the source of information is INTELLIGENCE and you will see that these items are now reported as if they were the gravitational constant, or the speed of light.

Jensen: "The fact that _g_ is more strongly genetic than most other psychological variables is not really controversial among empirical researchers in this field. It is highly controversial only in the popular media. Just try to find any real controversy among the experts who know the research on this issue." Miele (2002) - Intelligence, Race, and Genetics: Conversations with Arthur R. Jensen - P. 79. This is precisely what I have been saying. Notice that the folks here who cite newspapers and Russian Studies experts, versus those who cite real science. On that same page, Jensen discusses the Snyderman-Rothman study. He specifically mentions the APA. The reading is well worthwhile, but too long for me to copy.

Is there now a biological theory of intelligence? Or are there competing theories?
There are various models of how the brain processes information. Some of these can be diagramed and are shown in The _g_ Factor. There are also the sideline theories that have been advanced by Gardner and Sternberg. Neither holds water and neither stands up to quantative analysis. As I mentioned before Gottfredson wrote a very long paper in INTELLIGENCE replying to Sternberg's Triarchic Model. She examined every tiny thing he had claimed and totally destroyed each item. Both of these models are discussed in The _g_ Factor. Gardner's ideas are so far out that they are not taken seriously by more than a few devotees.

What are 'chronometric measurements'?

They include response time measurements to elementary cognitive tasks, such as pressing a button when a light goes on; and inspection time measurements, which are designed to measure the shortest time that a stimulus can be presented to an individual and still be recognized correctly. Brand has written a lot about IT and Jensen has written a lot about RT, but both areas have been widely reported by other researchers.

What is the typical experimental error in _g_ from these? Ditto, for EEG measurements?
I don't know from memory and don't have more time to devote to looking for the answer. The bottom line is that both measurements correlate strongly with _g_. RT has a somewhat stronger correlation, if a battery of diverse ECTs are used. IT is usually done in a single format, so there is not a battery of tests.

How are the 'zero point' and scale of _g_ defined?
_g_ is usually stated in terms of percentile, since the number is usually extracted from a conventional IQ test. IQ tests are not true ratio scales. Jensen has mentioned (many times) that a true ratio scale would be very valuable. After the last ISIR conference, Rushton said that he thought we were getting there. The tool he had in mind was chronometric measurement. I was irritated that I skipped the meeting because it was 3000 miles away, but this year I may spend the money and attend.

[NoahAfrican]

Mandrak...do you need an napkin or towel? Just wondering due to all the intellectual masturbating that you are doing. Give it a rest already ok...whites are the suprem God like being of the Earth and Universe...Ok...now....or are you on a campaing, like Hitler, to dominate the world with this Ayran philosoply.

[Evo]

Do you mean her "kangaroo" link? I had seen that one before. It was put up by Steve Kangas, who says on his page that he is a student seeking a degree in Russian Studies. Is that a good source of scientific information? He identifies himself as an ultra-liberal and obviously has a very strong political agenda. If you look at his references, you will see that they include these scientific sources:
The San Francisco Chronicle
People For The American Way
USA Today
Boston Globe
The New York Times Magazine
Discovery Journal
The Nation,
Rolling Stone
Newsday
Newsweek. You intentionally omitted all of the references from the American Psychological Association and the Human Genome Project. How do you expect anyone to believe anything you say when you try to deceive them? If you have nothing to hide, why do you intentionally skew this list? Here are the sources Mandrake left out. I am disappointed in you Mandrake, I thought we could start over and debate this reasonably. Since you had to pick the other references from around them, you went to a deal of trouble to omit them.

3. Tori DeAngelis, "Psychologists question findings of Bell Curve," APA Monitor, American Psychological Association, October, 1995.

4. "Task Force Releases Report in Response to Bell Curve," American Psychological Association, Press Release, Fall 1995.

5. "APA Task Force Examines the Knowns and Unknowns of Intelligence," American Psychological Association, Press Release, September 15, 1995.

11. Lori B. Andrews, Dorothy Nelkin and endorsing members of the Human Genome Project, "The Bell Curve: A Statement," letter to the editor, Science, January 5, 1996.

Also, I borrowed that link from someone else here at PF. You don't even know who you are insulting, it isn't me.

I didn't see the letter to Science. Can you provide me with the link? Do you have the names and job positions of the people who wrote the letter? http://www.people.virginia.edu/~rjh9u/bellcrv.html and a longer version of this statement was endorsed by the National society of Genetic Counselors.

APA is not a group of psychometricians, it is a group of psychologists, a few of whom may be psychometricians. You seem to think quite highly of psychometricians, when I have sometimes heard "psychometrics" referred to as "voodoometrics", which I think isn't nice since there are good people and bad people and I disagree with labeling groups of people, it isn't right or completely true. When a letter goes out, it is not the joint finding of the entire membership nor is it the joint finding of those members who are actually qualified to make a judgement. Which is exactly why the APA formed an unbiased committee , including Thomas Bouchard. You can't get much more pro Bell Curve than that.

The members of the task force were chosen during a detailed process. Dr. Ulric Neisser, professor of psychology at Emory University, was appointed chair of the task force, several other members were nominated by one of several APA constituencies, and remaining members were selected in order to provide a range of expertise and perspectives. The task force included:

Ulric Neisser, Emory University (chair of the task force)
Gwyneth Boodoo, Educational Testing Service
Thomas J. Bouchard, Jr., University of Minnesota
A. Wade Boykin, Howard University
Nathan Brody, Wesleyan University
Stephen J. Ceci, Cornell University
Diane F. Halpern, California State University, San Bernadino
John C. Loehlin, University of Texas, Austin
Robert Perloff, University of Pittsburgh
Robert J. Sternberg, Yale University
Susana Urbina, University of North Florida

At this point, the only people doubting the 100 year study of the variance in intelligence are crackpots. So, you claim the people listed above are crackpots? Nice.

Here is another link on The Bell Curve from the University of Wisconsin.

http://www.ssc.wisc.edu/irp/featured/bellcurv.htm

[Nereid]

Psychometrics is the use of scientific instruments to gather quantitative psychological data. An IQ test would be an example of a psychometric instrument — despite its reliance on voluntary responses from test subjects. Therefore, psychometrics does not merely refer to the use of instruments — such as the more-recently-invented evoked-potentials tests — that make use of involuntary resonses from test subjects.


M-W Unabridged definition of psychometrics:

Etymology: International Scientific Vocabulary
1 : relating to the measurement of mental or subjective data
2 : relating to or being a mental test or psychological method whose results are expressed quantitatively rather than qualitatively Psychometrics is about intelligence. It started with the development of mental tests, which became IQ tests. Psychometrics seeks to measure intelligence, to find its correlates, and to understand the root causes for the differences that are found. Essentially all of the work in psychometrics now falls in the category of "differential psychometrics." It is based on experimental and correlational methods.

[...]

"Intelligence" is the entire field. If it does not relate to intelligence, it is not part of psychometrics.That's quite a difference (of opinion?)! So I did some research of my own ... Here (http://www.fordham.edu/aps/whatpsy.html) I found the following: "Psychology is a diverse and exciting field. As pioneers in a relatively youthful science psychologists worldwide strive to improve every aspect of human life, from planning urban construction and zoning to human-computer interaction. Across all disciplines of psychology there is a common thread that unites all researchers and scientists in the field. This unifying discipline is psychometrics." This helped me a lot; rather than just intelligence, the term 'psychometrics' seems to refer to psychology as a whole. This also puts the relationship with neuroscience and biology in general into perspective - the more 'fundamental' field of science is the newer neuroscience.Do you mean her "kangaroo" link? I had seen that one before. It was put up by Steve Kangas, who says on his page that he is a student seeking a degree in Russian Studies. Is that a good source of scientific information? He identifies himself as an ultra-liberal and obviously has a very strong political agenda. If you look at his references, you will see that they include these scientific sources: I decided to check the sources on the page for myself; I see that Evo has already posted some words about these (including a link to the Andrews and Nelkin 1996 Letter to Science). From these materials I gather that there is (or was) quite a deal of controversy among US psychologists about the book. To be sure I don't misunderstand, are Andrews and Nelkin 'crackpots'? What about members of the APA taskforce - are they crackpots too?

[hitssquad]

I'm still interested in knowing whether Jensen (and others) have been clear that their work has validity only in the geographical region in which it was conducted, or whether it can be used globally (and if so, why).

We have seen in the foregoing chapters that many lines of psychometric evidence converge to the conclusion that, by and large, current standardized tests of general mental ability and scholastic achievement, as well as many vocational aptitude tests, are not biased with respect to any native-born, English-speaking minority groups in the United States. This generalization can be extended in the case of nonverbal tests to native-born non-English-speaking minority groups as well. These conclusions are confined to native-born subpopulations within the United States, not because of any evidence on immigrant groups or on populations outside the United States that is at odds with the present conclusions, but only because of the lack of relevant studies that would warrant any broader conclusions.(Arthur Jensen. Bias in Mental Testing (http://www.amazon.com/exec/obidos/tg/detail/-/0029164303). 1980. Chapter 15: Uses and Abuses of Tests. p715.)

[Nereid]

Thanks hitssquad. I have a vague recollection that Jensen said something similar in a later work too.

To me, this Jensen statement is an indication that he takes science seriously; in particular, since there is no underpinning, widely accepted biological (or neurological) theory of psychology, extrapolations beyond the 'experimental subject universe' should be made only with extreme caution.

An example of how complex the relationship between behaviour, genetics, and brain function is reported recent findings on depression (a much stigmatised condition which may affect ~10% of us all).

[Mandrake]

That's quite a difference (of opinion?)!
I must be missing something. What difference do you see?

"Psychology is a diverse and exciting field. As pioneers in a relatively youthful science psychologists worldwide strive to improve every aspect of human life, from planning urban construction and zoning to human-computer interaction. Across all disciplines of psychology there is a common thread that unites all researchers and scientists in the field. This unifying discipline is psychometrics."
Psychology is a broad field that contains many areas of specialization that have little or nothing to do with psychometrics. If a behavior or ability is dependent on intelligence (such as learning rate), it links to psychometrics. I expect you can obtain a list of Intelligence paper titles from Sciencedirect.com, but that may not be available to people who do not belong to ISIR. A list of paper titles will quickly define for you the actual subjects that are being researched in this field.

This helped me a lot; rather than just intelligence, the term 'psychometrics' seems to refer to psychology as a whole.
I think that is not correct and not close to correct.


From these materials I gather that there is (or was) quite a deal of controversy among US psychologists about the book.
There was a lot of controversy outside of the field of psychometrics. This was largely due to ignorance of the findings of the prior 75 years. I assume you read and understood the letter to the Wall Street Journal that addressed 25 salient points from The Bell Curve (posted in another thread). The person who posted that letter also listed the names of the people who signed it. These people were not surprised at anything in the book, since they were familiar with the literature. It is obvious that the negative responses were largely from "outsiders" since those same people did not comment when Seligman's book was released about 2 years earlier. The press and liberals didn't have any idea that the white-black IQ gap had been quantified for at least 3/4 of a century. Spearman's Hypothesis was formulated in 1927 (from memory, you can verify the date) and remains accurate today. Bias in Mental Testing also went into considerable detail about the gap. In fact, the book was written largely to demonstrate the applicability of standard IQ tests to all population groups. All of Chapter 4 is devoted to the subject of IQ distribution. Anyone capable of reading the book (is is not pablum) in 1980 would have had no trouble understanding the details of the white-black gap. On page 99 there is a large graph of the normative population and of blacks. So, why the excitement, when The Bell Curve recited what was already a matter of history, going back to Spearman???

To be sure I don't misunderstand, are Andrews and Nelkin 'crackpots'?
Perhaps a better question to ask is what is the background of these two ladies? Are they schooled in psychometrics? Have they published in peer reviewed journals? Have they written recognized text books on intelligence? I have never heard of them. Can you tell me about their qualifications to make the sorts of comments that appear in that letter? I too did some research:
The late Dorothy Nelkin, a sociologist, was a professor at the New York University School of Law.
Lori B. Andrews
Distinguished Professor of Law; Director of the Institute for Science, Law and Technology; and Associate Vice President

As you can see, neither of these people are psychometricians and neither seems to have a close connection with that field of study. I do not understand the merits of criticisms from sociologists and lawyers who have not conducted psychometric research and are not experts in the field.

What about members of the APA taskforce - are they crackpots too?
I think I addressed the APA in my last message. The taskforce comments were vague and were apparently designed to say as little as possible. Do you have information as to the names of the task force members? Are they people who have published in this field?

[NoahAfrican]

You all have put up a good fight against Mandrak and his likes. However, it is a loosing battle. You all must understand and accept that logic is a poor weapon to employ against emotions. Mandrak has an emotional investment in these beliefs and no amount of intellectual and professional contradictions of the hypothesis of others, that he presents, will change his opinion.

I guess I have been around this block enough time to know intransigence and closed minds when I encounter such. However, your attempts are not in vain in that hopefully others who are silently reading will have the equal and opposite force (counter opinions and hypotheis) to offset his foolery...but rest asured that you will not change his opinion.

[Evo]

Perhaps a better question to ask is what is the background of these two ladies? Are they schooled in psychometrics? Have they published in peer reviewed journals? Have they written recognized text books on intelligence? I have never heard of them. Can you tell me about their qualifications to make the sorts of comments that appear in that letter? I too did some research:
The late Dorothy Nelkin, a sociologist, was a professor at the New York University School of Law.
Lori B. Andrews
Distinguished Professor of Law; Director of the Institute for Science, Law and Technology; and Associate Vice President Dorothy Nelkin, Professor of Sociology, member of the Human Genome Project, here are some of her publications, these just from 1990-1995

Dreyfuss, Rochelle Cooper ; Nelkin, Dorothy
The jurisprudence of genetics.
Vanderbilt Law Review. 1992 Mar; 45(2): 313-348.
adoption ,autonomy , behavioral genetics , criminal law , DNA fingerprinting , employment , eugenics , family relationship , females , genetic counseling , genetic disorders , genetic screening , genetics , genome mapping , law , legal aspects , legal liability , mass screening , occupational exposure , parent child relationship , personhood , prenatal injuries , reproductive technologies , science , self concept , social discrimination , social impact , sociobiology , surrogate mothers , values , wrongful life

Nelkin, Dorothy
The double-edged helix.
New York Times. 1994 Feb 4: A23.
behavioral genetics ,eugenics , genetic disorders , genetic predisposition , genetic screening , genetics , genome mapping , human characteristics , mass media , social discrimination , social impact

Nelkin, Dorothy
The social power of genetic information.
Kevles, Daniel J.; Hood, Leroy, eds. The Code of Codes: Scientific and Social Issues in the Human Genome Project. Cambridge, MA: Harvard University Press; 1992: 177-190, 344-345.
behavioral genetics ,diagnosis , DNA data banks , economics , education , employment , genetic disorders , genetic screening , genome mapping , health care , insurance , law enforcement , legal aspects , mass screening , normality , prenatal diagnosis , risks and benefits , social discrimination , social impact , stigmatization

Nelkin, Dorothy
The rhetoric of scientific revolution. .
[B]Hastings Center Report. 1992 Jul-Aug; 22(4): 38-39.
book review ,ecology , genetic intervention , genetic screening , genome mapping , industry , public policy , recombinant DNA research , regulation , risks and benefits , science , social impact , socioeconomic factors

Nelkin, Dorothy
Diagnosis: the social implications of emerging biological tests.
Blank, Robert H.; Bonnicksen, Andrea L., eds. Emerging Issues in Biomedical Policy: An Annual Review. Volume I. New York: Columbia University Press; 1992: 215-224.
behavior control ,behavioral genetics , biomedical technologies , dangerousness , data banks , diagnosis , employment , genetic disorders , genetic screening , genome mapping , health insurance , law enforcement , mass screening , mental health , prenatal diagnosis , psychiatric diagnosis , social control , social discrimination , social impact , stigmatization

Nelkin, Dorothy ; Tancredi, Laurence
Dangerous Diagnostics: The Social Power of Biological Information; with a new Preface.
Chicago, IL: University of Chicago Press; 1994. 207 p.
Originally published by Basic Books; 1989.
adults ,alcohol abuse , behavior control , behavior disorders , behavioral genetics , biomedical technologies , children , chromosome abnormalities , diagnosis , DNA fingerprinting , drug abuse , economics , education , forensic psychiatry , genetic disorders , genetic predisposition , genetic screening , health care delivery , industry , insurance , law enforcement , mandatory testing , mass screening , normality , occupational medicine , prenatal diagnosis , privacy , psychiatric diagnosis , social control , social discrimination , social impact , stigmatization , violence

Nelkin, Dorothy
Genome: the social power of biological tests (1).
International Journal of Bioethics. 1990 Sep; 1(3): 140-145.
behavioral genetics ,conflict of interest , diagnosis , economics , education , employment , eugenics , genetic disorders , genetic screening , genome mapping , health care , health insurance , institutional policies , mass screening , normality , physicians , public policy , social control , social discrimination , social impact

Nelkin, Dorothy
Living inventions: animal patenting in the United States and Europe.
Stanford Law and Policy Review. 1992-93 Winter; 4: 203-210.
accountability ,animal rights , decision making , drug industry , ecology , economics , genetic intervention , government regulation , human rights , hybrids , industry , information dissemination , international aspects , investigators , justice , morality , patents , political activity , public opinion , public participation , public policy , recombinant DNA research , risks and benefits , speciesism , transgenic animals , universities

http://www.csu.edu.au/learning/ncgr/gpi/odyssey/cloning/Nelkin_works.html

The other woman - Lori B. Andrews
Distinguished Professor of Law; Director of the Institute for Science, Law and Technology; and Associate Vice President

Since passing her bar exam the day Louise Brown, the first test-tube baby was born, Lori Andrews has become an internationally-recognized expert on biotechnologies. Her path-breaking litigation about reproductive and genetic technologies and the disposition of frozen embryos caused the National Law Journal to list her as one of the "100 Most Influential Lawyers in America."

Today, Professor Andrews is a distinguished professor of law at Chicago-Kent; Director of IIT's Institute for Science, Law and Technology; and in Spring 2002, she was a visiting professor at Princeton University. She received her B.A. summa cum laude from Yale College and her J.D. from Yale Law School.

Professor Andrews has also been involved in setting policies for genetic technologies. She has been an adviser on genetic and reproductive technology to Congress, the World Health Organization, the National Institutes of Health, the Centers for Disease Control, the federal Department of Health and Human Services, the Institute of Medicine of the National Academy of Sciences, and several foreign nations including the emirate of Dubai and the French National Assembly. She served as chair of the federal Working Group on the Ethical, Legal, and Social Implications of the Human Genome Project. She recently served as a consultant to the science ministers of twelve countries on the issues of embryo stem cells, gene patents, and DNA banking. She has also advised artists who want to use genetic engineering to become creators with a capital "C" and invent new living species.

Professor Andrews is the author of ten books

http://www.kentlaw.edu/faculty/andrews_bio.html

Sounds like they're qualified to me.

[nuenke]

In the meantime, can you point me to a paper describing the commonly accepted experimental protocols? I'm particularly interested in subject selection and the extent to which double-blind protocols are employed. Hmm. I'm still interested in knowing whether Jensen (and others) have been clear that their work has validity only in the geographical region in which it was conducted, or whether it can be used globally (and if so, why).Sorry that I wasn't clear.

A good book on psychometrics that goes into experimental protocols is:

Modern Psychometrics: The Science of Psychological Assessment by Rust and Golombok, 1999. I am sure Amazon has other textbooks available on the subject as well.

Also, the geographical region of study in intelligence is in fact global. See Lynn and Vanhanen's "IQ and the Wealth of Nations" and the numerous papers written following the books release two years ago.

[nuenke]

Sounds like they're qualified to me.

The three academic areas that do not reflect the scientific method includes cultural anthropology, social science and law, along with a few others. Of course, there is no way to have a scientific discussion of race and intelligence because humans become irrational in these areas: just like abortion, religion, and a host of other subjects.

When it comes to racial issues, humans fail the test of scientific investigation--it is just too political. The research into heuristics and biases, along with numerous other books are now exploring how humans are all about deception and self-deception. That is why we can pursue quantum mechanics and going to the moon, but we will deny there is such a thing as intelligence while putting decals on our bumpers stating "my son is an honor student at bid-deal high."

[Moonbear]

g is the source of broadest common variance in any given matrix of mental ability tests. Factor-loadings (including g-loadings) of mental tests are determined by factor analyzing the results of tests adminstered to multiple subjects. (In terms of the most widely used IQ tests, the vocabulary subtests tend to be revealed by factor analysis as having the highest g-loadings of any subtest.)

Since g is the most-general factor of mental-ability tests, it is the factor that is most predictive of general outcomes. Relatively narrow outcomes tend to be better predicted by narrower ability factors such as those that have been borrowed by Howard Gardner to form his list of "multiple intelligences."

I may sound really dense here, but I have to admit, this didn't make a whole lot of sense to me. "g is the source of broadest common variance..." So, is it a statistical measure? You give someone a bunch of tests, then compute the variance in those test results, and that gives you a result called g? Or is it some "thing" that supposedly causes that variance? From some of the other posts, I see that it's reported as a percentage. Percentage of what? If it's based on the results of IQ tests, then of course it would be correlated to IQ (something I've seen mentioned often in assorted threads here). So, how does it differ from IQ and the way IQ scores are calculated?

Or, perhaps another way of asking it is this: what does the score mean? If someone has a high g score, does that mean they are supposed to be more intelligent than someone with a low g score? Does it mean they are more consistent across different measures, such as verbal and analytic skills? I know much of the debates here are dealing with what g might predict, but that's not what I want to know, I want to know what it means in the here and now. What do we KNOW about it, not what we think it might tell us about the future? Or is it just a form of mathematical modeling, attempting to fit things like IQ, test scores, and some sort of measure of real life ability into some sort of equation/model for just that purpose, trying to predict outcomes based on just a few of those measures?

Correlations are fine and interesting and lead to hypotheses to test, but they do not prove causation. It seems there is a lot of weight being put onto correlations here and in related threads.

Sorry if I'm being very verbose and asking essentially the same question many different ways, but I just haven't seen an answer that really holds much meaning to the question I'm really trying to ask, so I'm trying to make it clearer just what it is that has me confused that I'm trying to get an answer about.

[selfAdjoint]

I may sound really dense here, but I have to admit, this didn't make a whole lot of sense to me. "g is the source of broadest common variance..." So, is it a statistical measure? You give someone a bunch of tests, then compute the variance in those test results, and that gives you a result called g?

You give a lot of people a lot of different IQ tests. You take all the scores, by person, test, and question number, and do a statistical procedure called factor analysis, trying to find which combination of questions reduces the most variance on the data. This is like a regression, only more so. The result will be a set of subsets of questions, ordered by effectiveness in reducung variance. The top candidate is called the first principal component. You then identify the questions and convert their scores to a number. Spearman's g is this number for the first principal component of just about every IQ test and surrogate ever invented. It is enormously stable and correlated with things like the SAT, the Armed Forces tests, and so on. It also has physical correlates like measured reaction time and volume of gray matter in the prefrontal cortex.

[Moonbear]

You give a lot of people a lot of different IQ tests. You take all the scores, by person, test, and question number, and do a statistical procedure called factor analysis, trying to find which combination of questions reduces the most variance on the data. This is like a regression, only more so. The result will be a set of subsets of questions, ordered by effectiveness in reducung variance. The top candidate is called the first principal component. You then identify the questions and convert their scores to a number. Spearman's g is this number for the first principal component of just about every IQ test and surrogate ever invented. It is enormously stable and correlated with things like the SAT, the Armed Forces tests, and so on. It also has physical correlates like measured reaction time and volume of gray matter in the prefrontal cortex.

Thank you so much for taking time to answer my questions! This is so much clearer to me. So, can any conclusions be drawn from the subset of questions that is used to compute the score for g? Do they have in common requiring a particular type of ability? As possible examples, spatial relations, verbal skills, analytical skills, forming associations between two different concepts, memorization tasks. The reason I'm asking is that now that I understand what g is, I'm wondering what about it makes it stable. Perhaps certain mental abilities are more important to survival on a more basic level, so are better conserved, whereas others are a "luxury" for those who have time to ponder the day away, so more variable? For example, key skills to surival...finding and remembering the places where food is, remembering which things made you sick so aren't good food, and remembering how to get from where you are to those places where the food are. So, basically, some memorization tasks and some spatial relations tasks. You don't need to know how to count to know if your belly is full, you don't have to add or subtract or multiply, you don't have to know a lot of words, though some basic communication to tell your family members where to find the food would be good, but you would need to make associations between different events...ate the green berries and later got a tummy ache, so green berries aren't good food. When it comes to solving problems that ask you to make analogies or find synonyms to words no normal person uses in every day conversation, I'd expect a lot more variation in ability simply because there is no real need for this skill.

[Mandrake]

Originally Posted by Mandrake
Do you mean her "kangaroo" link? I had seen that one before. It was put up by Steve Kangas, who says on his page that he is a student seeking a degree in Russian Studies. Is that a good source of scientific information? He identifies himself as an ultra-liberal and obviously has a very strong political agenda. If you look at his references, you will see that they include these scientific sources:
The San Francisco Chronicle
People For The American Way
USA Today
Boston Globe
The New York Times Magazine
Discovery Journal
The Nation,
Rolling Stone
Newsday
Newsweek.

Evo: You intentionally omitted all of the references from the American Psychological Association and the Human Genome Project.
You noticed? Maybe you thought my comment about "scientific sources" was serious? Guess not. Let me explain it to you ... I was making fun of the outrageous sources that were listed. I do not object to the use of a source that may have some scientific merits. Guess the subtlety was a bit too much for you.

How do you expect anyone to believe anything you say when you try to deceive them?
I made the horrible mistake of thinking that readers could understand what I wrote. You didn't.

If you have nothing to hide, why do you intentionally skew this list? Here are the sources Mandrake left out. I am disappointed in you Mandrake, I thought we could start over and debate this reasonably. Since you had to pick the other references from around them, you went to a deal of trouble to omit them.

A little testy today? I am sorry I made fun of the newspaper sources that you apparently believe are vehicles for serious science.

3. Tori DeAngelis, "Psychologists question findings of Bell Curve," APA Monitor, American Psychological Association, October, 1995.
This person identifies herself as a "writer." She does write about subjects that pertain to intelligence. So does the guy who is majoring in Russian Studies (Kangas). Does this person have any real credentials? The problem with the references you and others have produced is that they are precisely from the uninformed groups who have an ax to grind, but who are ignorant of the reliant science.

5. "APA Task Force Examines the Knowns and Unknowns of Intelligence," American Psychological Association, Press Release, September 15, 1995.
I have read this. I assume you have read it. What parts support your claims that The Bell Curve is invalid and that its authors are racists? Do you believe that the entire group of practicing psychometricians are evil racists? If so, does that go all the way back to Spearman?

11. Lori B. Andrews, Dorothy Nelkin and endorsing members of the Human Genome Project, "The Bell Curve: A Statement," letter to the editor, Science, January 5, 1996.
What expertise do you ascribe to a sociologist and a lawyer? These people are not experts in the field of psychometrics, nor have they published research findings in psychometrics. They are simply critics, who fit the mold of your newspaper and Russian Studies experts. Why are you so attracted to people who have little commitment to the study of intelligence, while holding in contempt the scientists who have devoted their entire careers to it? When you are ill, do you hold physicians in contempt and seek help from a newspaper?

Originally Posted by Mandrake
APA is not a group of psychometricians, it is a group of psychologists, a few of whom may be psychometricians.

Evo: You seem to think quite highly of psychometricians, when I have sometimes heard "psychometrics" referred to as "voodoometrics", which I think isn't nice since there are good people and bad people and I disagree with labeling groups of people, it isn't right or completely true.
If we were discussing astronomy, would you think it appropriate to take expert commentary from astronomers, or lawyers? If we were discussing insects, would you want to be quoting an entomologist, or someone who describes himself as an admirer of Russians and an ultra liberal?

Originally Posted by Mandrake
When a letter goes out, it is not the joint finding of the entire membership nor is it the joint finding of those members who are actually qualified to make a judgement.
Evo: Which is exactly why the APA formed an unbiased committee , including Thomas Bouchard. You can't get much more pro Bell Curve than that.
The APA report addresses some issues quite well; it addresses others incompletely; and it misrepresents some issues. Consider the discussion about heritability. They discuss only MZA data and say nothing about path analysis. Why? The results are in agreement, but the literature claims are that path analysis is more robust. In this area, they had no way of knowing what would later be discovered by Dr. Paul Thompson at UCLA: "We were stunned to see that the amount of gray matter in frontal brain regions was strongly inherited, and also predicted an individual's IQ score..." His work was done with MRI. Their coverage of the Scarr-Weinberg findings was poor.

[Mandrake]

Since you (Evo) place a lot of weight on the people who served on the task force, I would like to make observations about some of them, supplemented by some of their material:

Ulric Neisser, Emory University (chair of the task force)
A real psychometrician. His interest has been in the Flynn Effect.

Thomas J. Bouchard, Jr., University of Minnesota

The scientific study of general intelligence: Tribute to Arthur R. Jensen
H. Nyborg (Ed.), 2003, Elsevier, Oxford, UK, ISBN0080437931
Thomas J. Bouchard:
This is a gem of a book and a fitting honor to a distinguished scientist and scholar.
Arthur Jensen has single-handedly reinvigorated the scientific study of human intelligence and his magnum opus—The g Factor: The Science of Mental Ability (Jensen, 1998) (henceforth, SMA)—will remain a definitive work for many years to come. As Jensen has shown, g lies at the nexus of a large set of causal empirical relationships that encompass every aspect of human life, from birth to death. This nexus links psychology to biology, genetics, neuroscience, sociology, demography, the humanities, and the arts. There is an emerging discipline called the Epidemiology of Human Intelligence. The book under review follows the Bell Curve (Herrnstein & Murray, 1994) and SMA in helping lay the foundations of that discipline.

Description versus strong inference --Thomas J. Bouchard Jr.
Intelligence, Volume 29, Issue 2 , March-April 2001, Pages 187-188
Since Scarr (1997) has shown quantitatively that socialization effects, found in studies of biological families, are confounded and almost all such effects can be explained by genetic factors, adoption controls are mandatory. Hand waving away the competing genetic hypothesis simply will not do.

A. Wade Boykin, Howard University
His interest seem to be restricted to blacks. He even wrote instructions for black psychologists, as if the skin color of a psychologist requires a different set of research instructions.

Nathan Brody, Wesleyan University

Here are a few of his comments from Kings of Men: Introduction to a Special Issue of the Journal of INTELLIGENCE (1998)

I believe that anyone who wishes to write about the issue of race and intelligence must acknowledge Jensen's formidable contributions to this topic and his comprehensive knowledge of this area of research. Jensen's book on bias in testing is an extraordinarily thorough and scholarly analysis of the issue of test bias (Jensen, 1980). I like to compare this book with another book that I admire greatly, Paul Meehl's monograph on Statistical vs. Clinical Prediction (Meehl, 1954). Both books serve to define the principal issues that must be understood in addressing the topics that they consider. Both books develop their arguments with unusual clarity and sophistication. And, to a remarkable extent, the conclusions reached in both books have stood the test of time and become part of the canon of empirically established generalizations that define our knowledge of important topics. Jensen established what is now close to the received wisdom of knowledgeable students of intelligence -- tests of intelligence are equally valid indices of the performance of individuals who differ with respect to their racial identification. In several technical senses of the term, they are not biased -- a conclusion endorsed in the recently published report of the American Psychological Association's task-force on intelligence composed of individuals with diverse views of the field (Neisser et al., 1996).

Jensen is not an ideologue or a person who is not able to respond to criticism in a fair way. He is a scientist with formidable technical skills who strives for an understanding of the topics that he addresses. In this regard, his work is a model of scientific decorum. We should all strive to emulate his ability to test our beliefs against a recalcitrant reality that often is resistant to our ability to represent it in distorted ways. In the long run, if we are clever and honest, it will impose its structure and truth on us rather than ours on it.

In my opinion, Jensen's most important contribution to the field is contained in his new book on the g factor (Jensen, 1998). In the first paper dealing with g, Spearman attempted to determine the g loadings of different measures of intelligence (Spearman, 1904).

Jensen (1998) links the g vector to several biologically relevant vectors. He notes that Pedersen et al. (1992) obtained heritability values for different tests in a battery of tests of intelligence administered to a sample of older Swedish adult MZ and DZ twins reared together and apart. The vector defining the heritability of the tests is correlated with the vector defining the independently ascertained g loadings, r = .77. Jensen provides additional evidence based on Wechsler sub-test g loadings indicating that the vector of g loadings is correlated with the vector of heritability values for Wechsler sub-tests.

Jensen's analyses of the correlates of g vectors provide the quantitative underpinning for what has long been apparent -- g is a biologically influenced heritable component of the commonality among diverse measures of intellect that is related to the ability of individuals to acquire knowledge in formal academic contexts. Perhaps we have always known this, but following Jensen's highly original use of analyses of the correlates of g vectors we know this with a kind of quantitative precision not heretofore available.

Jensen's work on the correlates of the g vector reveals some of his best attributes -- an ingenious ability to develop quantitative analyses that address fundamental issues in highly original ways that advance our knowledge of critical issues in the field.

Stephen J. Ceci, Cornell University
Focus is on children. His positions on many issues are in conflict with real world findings.

Diane F. Halpern, California State University, San Bernadino
Her work is in the area of family issues and children, not psychometrics.

John C. Loehlin, University of Texas, Austin

His comments pertaining to the Texas Adoption Project from Intelligence, Volume 24, Issue 2 , 1997, Pages 323-328

The children have so far been studied twice-once at the time of the initial study, when they averaged about 8 years old (although spanning a range of ages), and again, roughly ten years later, when most of them were late adolescents or young adults. The results with regard to IQ were straightforward enough to delight even a Willer-man. The adoptive childtens’ IQs resembled those of their birth mothers, whom they had never seen, more than they did those of their adoptive mothers, with whom they had lived all their lives. Biologically unrelated children reared as siblings (pairs of adopted children in the same home, or an adopted and a biological child) resembled one another to some degree at the time of the first testing, when they were still children, but by the time of the second testing, when most of them were late adolescents or young adults, these cormlations had dropped essentially to zero. That is, children who grew up together but who did not share a genetic resemblance were somewhat similar in their measured IQs when they were young, but by late adolescence their genetic differences had expressed themselves, and they were as different as any two randomly-selected members of the (somewhat restricted) population to which they belonged.


Robert Perloff, University of Pittsburgh
Professor of Business Administration. Expert? :-)

Robert J. Sternberg, Yale University

I have discussed Sternberg here before. He advocates his Triarchic Theory, which does not stand up to scrutiny, as has been demonstrated dramatically by Linda Gottfredson.

Originally Posted by Mandrake
At this point, the only people doubting the 100 year study of the variance in intelligence are crackpots.
Evo: So, you claim the people listed above are crackpots? Nice.
Evo, your personal contempt has replaced rational thought. Do you seriously think that the people in question doubt the variance in intelligence that has been demonstrated over the past century? Try reading some of the comments they made, which I quoted. You really don't get it do you?

Here is another link on The Bell Curve from the University of Wisconsin.
Did you read this article? If so, what are your thoughts about it? Just posting a link by two economists doesn't add much to the discussion. Is there some reason why you consider that psychometrics is a subcategory of economics? My reading of the paper showed that the authors used approaches that appear to be reasonable, but which, as usual, ignore the details of what is known about the subject. This is apparent in their discussion of heritability. What are your deepest and most profound thoughts on this paper? Oh, I forgot to ask, did you read it before posting the link??

[Mandrake]

Dorothy Nelkin, Professor of Sociology, member of the Human Genome Project, here are some of her publications, these just from 1990-1995
I had already looked and found that these women had no background in psychometrics. Sorry to inform you, but the areas addressed by their publications (however important they may be for other purposes) are not sufficient to qualify them to address psychometric issues with authority. It remains amazing to me to see how important it is to you to show us all that there are people in various other fields who don't understand psychometrics, but who say what you want to hear.

[Moonbear]

Of these, the brain volume subject has received particularly prolonged study. The development of fMIR technology has enabled researchers to identify and measure the volumes of specific parts of the brain and to correlate them to _g_ (even group factors show up as specific locations). The research was done by Richard Haier and was presented at the 2003 ISIR conference. This is cutting edge material.

As promised, I'm trying to get back to this topic when less tired...and now I also have a better idea of what "g" is, so that helps.

It occurs to me that my initial confusion on this is that my interpretation of "specific" brain regions is probably different from what you meant. Using MRI, you can measure gross brain structures that have clearly defined boundaries, such as cortex, cerebellum, hippocampus, corpus callosum. You can also use methodologies that tell you what areas are "activated" during certain tasks by measuring changes in blood flow or glucose uptake, but these sorts of analyses are often open to varied interpretations (even in less controversial areas than intelligence), and it doesn't reflect the size of that brain area, just the part of it that is being used. The two general interpretations that can be taken when there is a group difference in the size of an area that "lights up" on an MRI is that either there is more activity, so a greater ability to use that region in that group, vs the group that shows less activity may be more efficient in processing of that task, so uses only a smaller area of the brain. The other controversy is whether blood flow and glucose uptake really translate into actual function. But for now, people are generally willing to accept that this is the case, and that controversy is more a nuance of the field. When I think of "specific" brain areas, I'm thinking of specific nuclei within a region. For example, in MRI, you can measure the volume or thickness of cortex in a given slice, and you could use some other landmarks to identify, for example, prefrontal cortex (I picked that because it's an area SelfAdjoint mentioned as correlating to g), but, within prefrontal cortex, there are multiple nuclei such as the infralimbic nucleus and prelimbic nucleus. These different nuclei contain a variety of different neuronal subtypes that differ between the nuclei both in neurotransmitters and receptors as well as functions...you get a very different neurological/behavioral outcome if different nuclei are lesioned, for example. And a variety of functions are attributed to this area, including things like working memory, impulse control, addiction, sexual behavior, some better described in the literature than others. I'm not sure if an MRI scan would really pick up differences associated with just parts of the PFC. And saying something is correlated to a change in the size of the PFC doesn't mean a lot to me...I would want to know which nucleus? Which cells in the nucleus? If someone had a deficit in the area related to working memory, that would certainly explain a lower test score, however, deficits in other areas might also lead to problems with taking tests that isn't related so much to intelligence as to just staying focused on the test.


The point of my comment is that these differences appear as group differences and correlate with _g_ independently of the group identity. For example, that means that the mean brain volume differences between US blacks and US whites are as expected, given the differences in mean IQs for these two groups. Chronometric measurements similarly vary between groups in proportion to the observed differences in _g_ between the groups.


I just found this fascinating article. It does show a clear relationship between IQ and head circumference, though they focus on the extremes, where head circumference was at or below 2 SD from the mean. The main conclusion is that head circumference and brain volume are related to IQ, and that this smaller head circumference and brain volume are strongly related to early childhood malnutrition. In this study, they were assessing adults, but the correlation to malnutrition is based on their earlier work that they also cite. There is also a really interesting paragraph in the introduction that explains that comparisons between racial groups are not valid, even when using height and weight to correct for head circumference variations, because height and weight are not unformly covariate with head circumference. Here is the citation and some excerpts (my editing for clarity is in red text).

Neuropsychologia 42 (2004) 1118–1131
Head size and intelligence, learning, nutritional status and brain development Head, IQ, learning, nutrition and brain
Daniza M. Ivanovic, Boris P. Leiva, Hernán T. Pérez, Manuel G. Olivares, Nora S. D´?az , Mar´?a Soledad C. Urrutia, Atilio F. Almagià, Triana D. Toro, Patricio T. Miller, Enrique O. Bosch, Cristián G. Larra´?n

To view the full article, go to: http://dx.doi.org and in the text box, enter:
doi:10.1016/j.neuropsychologia.2003.11.022

Abstract
This multifactorial study investigates the interrelationships between head circumference (HC) and intellectual quotient (IQ), learning,
nutritional status and brain development in Chilean school-age children graduating from high school, of both sexes and with high and low
IQ and socio-economic strata (SES). The sample consisted of 96 right-handed healthy students (mean age 18.0 ± 0.9 years) born at term.
HC was measured both in the children and their parents and was expressed as Z-score (Z-HC). In children, IQ was determined by means
of theWechsler Intelligence Scale for Adults-Revised (WAIS-R), scholastic achievement (SA) through the standard Spanish language and
mathematics tests and the academic aptitude test (AAT) score, nutritional status was assessed through anthropometric indicators, brain
development was determined by magnetic resonance imaging (MRI) and SES applying the Graffar modified method. Results showed that
microcephalic children (Z-HC ? 2S.D.) had significantly lower values mainly for brain volume (BV), parental Z-HC, IQ, SA, AAT, birth
length (BL) and a significantly higher incidence of undernutrition in the first year of life compared with their macrocephalic peers (Z-HC >
2 S.D.). Multiple regression analysis revealed that BV, parental Z-HC and BL were the independent variables with the greatest explanatory
power for child’s Z-HC variance (r2 = 0.727). These findings confirm the hypothesis formulated in this study: (1) independently of age,
sex and SES, brain parameters, parental HC and prenatal nutritional indicators are the most important independent variables that determine
HC and (2) microcephalic children present multiple disorders not only related to BV but also to IQ, SA and nutritional background.

Some authors emphasise that, at present, there is no
meaningful basis for the comparison of brain sizes within
and between racial groups and sexes; the control for body
size across racial groups (and sexes) is rendered difficult
because bodies do not just differ only in H(Height) and W (Weight)(Peters
et al., 1998). In the present study, the correlations between
BV (Brain Volume)and H and W were very low, as we informed in a
previous report (Ivanovic et al., 2002) and the analysis of
covariance (Guilford & Fruchter, 1984) revealed that no
significant effect of sex, H and W was observed for BV;
however, despite of this, values were adjusted by body size
(W and H) but were so similar to absolute values that only
these are reported in the present study.

HC (Head Circumference) has been recognised as the most
sensitive anthropometric index of prolonged undernutrition
during infancy, associated with intellectual impairment especially
verbal IQ, such as in our study (Ivanovic et al.,
2000d; Leiva et al., 2001; Stoch et al., 1982). Undernutrition
was significantly more prevalent in children with a low HC
(<?2 S.D.) who presented the lowest verbal IQ, BV (Brain Volume) and
APD (Anterior-Posterior Distance of the brain) values and this latter finding is especially outstanding
since APD involves language and visualisation areas (Stoch
et al., 1982; Willerman et al., 1991); this could explain that
in children with low HC (<?2 S.D.), verbal skills are more
deteriorated than non-verbal skills (Ivanovic et al., 2000d;
Stoch et al., 1982). In children with HC >2 S.D., verbal IQ
was higher than nonverbal IQ and in groups with a “normal
HC “ (mean±2 S.D.) similar values were found between total,
verbal and non-verbal IQ although IQ was significantly
higher in 0–2 S.D. group. Findings from several studies
emphasise that among preschoolers HC might reflect better
than body H the impact of nutritional deficiencies at an
early age; this measurement is useful in the identification of
the period during which malnutrition occurred (Johnston &
Lampl, 1984; Malina et al., 1975).

It has been suggested that individual differences
in myelination, which affects neural transmission
rates, may be the basis for the HC–BV–IQ correlation although
there is a low correlation between neural speed and
mental speed, suggesting that other mechanisms must be involved
(Miller, 1994; Tan, 1996; Vargas et al., 2000;Wickett
& Vernon, 1994). Delayed myelination and abnormalities in
neuron migration have been described as the most predominant
disorders in children with associated neurologic findings...

[Evo]

You noticed? Maybe you thought my comment about "scientific sources" was serious? Guess not. Let me explain it to you ... I was making fun of the outrageous sources that were listed. I do not object to the use of a source that may have some scientific merits. Guess the subtlety was a bit too much for you

A little testy today? I am sorry I made fun of the newspaper sources that you apparently believe are vehicles for serious science..They are references to where certain quotes and other information came from, they aren't supposed to be scientific references. I thought that was obvious, I guess not.

I will respond to the rest later when I have more time, it might be tomorrow.

[Evo]

I had already looked and found that these women had no background in psychometrics. Sorry to inform you, but the areas addressed by their publications (however important they may be for other purposes) are not sufficient to qualify them to address psychometric issues with authority. It remains amazing to me to see how important it is to you to show us all that there are people in various other fields who don't understand psychometrics, but who say what you want to hear.Like it or not Mandrake, those two are extremely qualified. I notice that you tend to dismiss and even skip over anyone or anything that disagrees with you, as in your list of the APA panel. If you agree with them, you praise them to the heavens and post comments of theirs that make you happy, if you don't agree with them, you post nothing of what they say and skip over them. You are so funny and predictable.

[Moonbear]

I've run out of characters in my above post to edit it...those strange apostrophe's followed by question marks in the authors names are supposed to be the letter i with an accent. For some reason, the characters didn't display correctly.

[Evo]

I just found this fascinating article. Well, I was going to get some work done, but your post and this article are too interesting.

I went to read the rest of the article and I can't. :frown: I don't have a password.

[hitssquad]

can any conclusions be drawn from the subset of questions that is used to compute the score for g? Do they have in common requiring a particular type of ability? As possible examples, spatial relations, verbal skills, analytical skills, forming associations between two different concepts, memorization tasks.
High g Loading
Matrix relations (.94)
Generalizations (.89)
Series completion (.87)
Verbal analogies (.83)
Likeness relations (.77)
Problem arithmetic (.77)
Paragraph comprehension (.73)
Perceptual analogies (.70)


Low g Loading
Maze speed (.04)
Crossing out numbers (.12)
Counting groups of dots (.14)
Simple addition (.23)
Tapping speed (.24)
Dotting speed (.27)
Paired-associates memory (.27)
Recognition memory (.31)(Arthur Jensen. The g Factor (http://www.questia.com/PM.qst?a=o&d=24373907). p35.)


Do they have in common requiring a particular type of ability?Spearman concluded that the tests that best reflect g are those that most involve the "eduction of relations and correlates." These are the tests that require inductive and deductive reasoning, grasping relationships, inferring rules, generalizing, seeing the similarity in things that differ (e.g., reward-punishment) or the difference between things that are similar (love-affection), problem solving, decontextualizing a problem (that is, distinguishing between its general, or essential, features and its specific, or nonessential, features). These all manifest the second and third "laws" of noegenesis--the eduction of relations and of correlates. They are contrasted with tests that call mainly upon speed of execution of simple tasks, performance of repetitious acts, simple cued recall of prior learned responses, execution of a practiced sequence or chain of responses, and direct imitation of another person's specific action without conscious transformation.(Ibid (http://www.questia.com/PM.qst?a=o&d=24373907). pp35-36.)


However:

Unlike group factors, g cannot be described in terms of the superficial characteristics or information content of the tests in which it is loaded. All mental tests have some degree of g loading and even extremely dissimilar tests (e.g., sentence completion and block designs) can have nearly equal g loadings. Group factors, on the other hand, are labeled and described in terms of the obvious characteristics of the kinds of tests that load on them (such as verbal, numerical, spatial visualization, memory, mechanical, to name a few of the established group factors).

Further, g is not describable in terms of any pure or unique behavior.... There is no single distinct type or class of behavior or materials required for the manifestation of g.... The fact that a certain class of tests measures g more efficiently than other tests does not qualify the characteristics of the former tests to be considered the "essence" or "defining characteristics" of g.(Ibid (http://www.questia.com/PM.qst?a=o&d=24373907). pp91-92.)



The Confusion of g with Mental Processes. It is important to understand that g is not a mental or cognitive process or one of the operating principles of the mind, such as perception, learning, or memory.... ...g only reflects some part of the individual differences in mental abilities....(Ibid (http://www.questia.com/PM.qst?a=o&d=24373907). p95.)



The knowledge and skills tapped by mental test performance merely provide a vehicle for the measurement of g. Therefore, we cannot begin to fathom the causal underpinning of g merely by examining the most highly g-loaded psychometric tests.(Ibid (http://www.questia.com/PM.qst?a=o&d=24373907). p74.)



When it comes to solving problems that ask you to make analogies or find synonyms to words no normal person uses in every day conversation, I'd expect a lot more variation in ability simply because there is no real need for this skill.A skill is not an ability. Skills result from practice, whereas abilities are inherent. However, higher ability results in faster and ultimately greater skill gain from any given amount of practice. This is why skill testing can indirectly indicate ability level.

As far as "no real need for" abilities that are characteristically highly g-loaded, every human activity is g-loaded to some extent, and persons with higher levels of g perform these activities more proficiently:


The effects of g encompass a broader range of uniquely human phenomena than any other psychological construct.... Applied research has concentrated on the importance of g in education, employment, economic development, health, welfare dependency, and crime.(Ibid (http://www.questia.com/PM.qst?a=o&d=24373907). p545.)

[Moonbear]

Well, I was going to get some work done, but your post and this article are too interesting.

I went to read the rest of the article and I can't. :frown: I don't have a password.

Well, at least I won't have to feel bad about keeping you from doing your work. Sorry about that. I thought that link I provided got me there without going through my university library...I guess it still knew :grumpy:

[Moonbear]

Hitsquad, all the information you've provided today is incredibly helpful! I feel I have a much better grasp of this subject now. Actually, a lot of what you included in this last post (#45) makes a lot of intuitive sense about what I've noticed in terms of my students and how well they learn.

Despite what an old professor once told me (he was quite fond of Piaget), I've found that students can be taught to make and understand relationships between things (that old prof told me they just reach that developmental stage on their own and some never do). The ability to identify relationships, especially complex relationships, really seems to reflect a student's likelihood of success, certainly as a scientist (there comes a point where rote memorization just doesn't carry you any further). So, it seems from what you're saying about g, is that it's sort of halfway between my views and my old prof's views. Students probably all possess the ability to identify those relationships among concepts, but some are slower than others to develop it and express the skill, and with some coaching, I can help them develop that ability into actual skill.

What you've posted isn't nearly so bleak sounding as the way I've seen it interpreted in other threads. Others seem to suggest (or maybe it was my misunderstanding of what they were saying) that if someone has a low g score, then they have no hope of doing what those with a high g score can do, but instead, it may just take them a little more time to get there. Well, that makes sense. We all know there are slow learners and fast learners. Sure, there are some people who have a developmental defect who just lack the brain cells to ever perform beyond a certain level, but I like to be an optimist and think that those within that broad range of "normal" are all equally capable of achieving the same thing, though those at one end of that normal spectrum may take a little longer than those at the other end.

[hitssquad]

I feel I have a much better grasp of this subject now.In that case, you probably have a looser grasp.



I've found that students can be taught to make and understand relationships between thingsOppositely, research has never been able to demonstrate any rise in g following intellectual exercise.



The ability to identify relationshipsg is not an ability.



Students probably all possess the abilityg is not an ability.



to identify those relationships among concepts, but some are slower than others to develop it and express the skillIdentification of novel relationships does not demonstrate skill. If it did, identification of novel relationships could be taught and learned.



and with some coaching, I can help them develop that ability into actual skill.No one has ever been able to successfully coach rises in g under controlled, documentable conditions.



Others seem to suggest that if someone has a low g score, then they have no hope of doing what those with a high g score can doSomeone with any given reliably-attained g score has no hope of successfully executing any task with a g threshold above his measured level of g.



but instead, it may just take them a little more time to get there.No.



Sure, there are some people who have a developmental defect who just lack the brain cells to ever perform beyond a certain level, but I like to be an optimist and think that those within that broad range of "normal" are all equally capable of achieving the same thing, though those at one end of that normal spectrum may take a little longer than those at the other end.This is analogous to the pre-Newton conception of gravity as affecting ballistic objects only at certain critical points in their flight paths. IOW, it was once thought that ballistic objects fly in perfectly straight lines to the apexes of their flight paths, then, once there, suddenly start dropping straight down. Your IQ distribution would have all of the "middle" people at exactly IQ 100 and a few retardates at a given retardate level and a few gifteds at a given gifted level. No one would have an IQ of 110, and no one would have an IQ of 90.

Contrarily, research has demonstrated that:

There are plausible reasons ... for assuming that individual differences in g have an approximately normal, or Gaussian ("bellshaped"), distribution, at least within the range of ±2σ from the mean. That range is equivalent to IQs from 70 to 130 on the typical IQ scale (i.e., μ = 100, σ = 15).(Arthur Jensen. The g Factor (http://www.questia.com/PM.qst?a=o&d=24373907). p88.)



I like to be an optimist and think that those within that broad range of "normal" are all equally capable of achieving the same thingThere has not been presented any reasoning why a possibility of massive equality in distribution of general mental ability should have any relationship with optimism.

[Mandrake]

So, can any conclusions be drawn from the subset of questions that is used to compute the score for g? Do they have in common requiring a particular type of ability?
When a test item requires thinking, it always calls on _g_. If a task has been learned to the point of automatic response, it is not calling on _g_ and is an example of a learned response. You can teach people to increase forward digit span, but in so doing, testing them on that ability is not as _g_ loaded as it would be if they were not trained. When they are then tested or reverse order digit span, they will not show that ability gains that were learned in forward recall.

As possible examples, spatial relations, verbal skills, analytical skills, forming associations between two different concepts, memorization tasks.

The items you listed are generally extracted at the second order of a factor analysis and are called group factors. Each of them is loaded on _g_, _s_, and _e_. The third order extraction yields _g_, which is the variance that is common to all of the group factors.

The reason I'm asking is that now that I understand what g is, I'm wondering what about it makes it stable.
_g_ is relatively stable over most of adult life and is so because it is rooted in physiology. I have previously listed the biological correlates of _g_. Such critical factors as nerve conduction velocity are biologically stable. The same applies to the degree of myelination. In old age, these may degrade and reduce intelligence. Some diseases may do the same thing. MS causes demyelination and causes IQ to decline.

[Mandrake]

Like it or not Mandrake, those two are extremely qualified.
I don't doubt that they are qualified in their fields. If you wanted to hire someone to represent you in a court of law, would you hire a psychometrician or a lawyer?

There is no requirement that a psychometrician hold a particular university degree. This is especially so because the field of psychometrics is quite removed from much of psychology and makes particularly heavy demands on statistical knowledge and laboratory research. The thing that distinguishes a psychometrician (or other specialist) is his devotion to the subject at hand, years of study, years of research, and participation in the publication of peer reviewed research. The women you listed are not qualified to peer review psychometric research.

I notice that you tend to dismiss and even skip over anyone or anything that disagrees with you, as in your list of the APA panel.
The APA group was selected for what appears to be political purposes. The APA is not a psychometric organization and as such, contains a lot of membership that is unqualified to deal with the subject. My observation is that you prefer comments from sources in proportion to their distance from the subject, wanting to believe only the things that originate from layman sources.

If you agree with them, you praise them to the heavens and post comments of theirs that make you happy, if you don't agree with them, you post nothing of what they say and skip over them.
If I know that the person is or is not qualified, I say so. You can always disregard my comments or call me a liar (as you have already done). That does not change my assessment. If I know nothing about the person, I cannot comment, can I?

You are so funny and predictable.
It is very kind of you to say so. This is an improvement over being called a racist and liar. I wonder if you interact with people in person with the same rudeness that I have seen in your messages?

I have a serious suggestion for you: Don't read my messages. For whatever reason, you cannot react to what I write in a civil way nor do you contribute positively to the ideas presented. As an alternative, simply read the comments by hitsquad. Read the recent ones he has posted in this thread in the past two days. Try to understand what he has presented and you will learn something useful about psychometrics. You are wasting your time being combative with me.[COLOR=Red]

[Mandrake]

It occurs to me that my initial confusion on this is that my interpretation of "specific" brain regions is probably different from what you meant. Using MRI, you can measure gross brain structures that have clearly defined boundaries, such as cortex, cerebellum, hippocampus, corpus callosum.

Here is a piece of the report I previously mentioned:
Human Intelligence Determined By Volume And Location Of Gray Matter Tissue In Brain Source: University Of California - Irvine Date: 2004-07-20

The researchers used a technique called voxel-based morphometry to determine gray matter volume throughout the brain which they correlated to IQ scores. Study results appear on the online version of NeuroImage. Previous research had shown that larger brains are weakly related to higher IQ, but this study is the first to demonstrate that gray matter in specific regions in the brain is more related to IQ than is overall size. Multiple brain areas are related to IQ, the UCI and UNM researchers have found, and various combinations of these areas can similarly account for IQ scores. Therefore, it is likely that a person’s mental strengths and weaknesses depend in large part on the individual pattern of gray matter across his or her brain.

“This may be why one person is quite good at mathematics and not so good at spelling, and another person, with the same IQ, has the opposite pattern of abilities,” Haier said.

While gray matter amounts are vital to intelligence levels, the researchers were surprised to find that only about 6 percent of all the gray matter in the brain appears related to IQ.

“There is a constant cascade of information being processed in the entire brain, but intelligence seems related to an efficient use of relatively few structures, where the more gray matter the better,” Haier said. “In addition, these structures that are important for intelligence are also implicated in memory, attention and language.”

The research does not address why some people have more gray matter in some brain areas than other people, although previous research has shown the regional distribution of gray matter in humans is highly heritable. Haier and his colleagues are currently evaluating the MRI data to see if there are gender differences in IQ patterns.

I just found this fascinating article. It does show a clear relationship between IQ and head circumference, though they focus on the extremes, where head circumference was at or below 2 SD from the mean.
I haven't had a chance to read the article, but I wonder why anyone would still be looking at head circumference, when we have a means of measuring brain volume and now a means of measureing the volumes of those small parts of the brain that contribute to intelligence?

The subject of brain size versus IQ has been studied and reported so extensively that the only likely new information is going to come from new laboratory techniques, such as those being used by Richard Haier.

Some brain and head size related factoids:

The average female brain is smaller than the average male brain. This is true, even after the size difference is corrected for relative differences in body size. The average male brain is about 12.5% heavier.

The average female brain has more neurons per unit volume than the average male brain (about 11%).

The average brain and head size is smaller for blacks than for whites.

The number of neurons in the brain is fixed by age 4, but the brain size to intelligence correlation is weak at age 4. By age 7 there is a significant within family effect. Miller argues that this is consistent with his myelination hypothesis because myelination of the brain is not significant at age 4, but is much more so at 7 and continues through adolescence.

The correlation between body size and brain size in adults is between .20 and .25.

The correlation between head size and IQ ranges from .10 to .25 (various studies), with a mean of .15.

The correlation (one study only) between head size and _g_ is .30.

The correlation between brain size, as measured by MRI, and IQ is .40 (corrected for body size).

[Moonbear]

Here is a piece of the report I previously mentioned:
Human Intelligence Determined By Volume And Location Of Gray Matter Tissue In Brain Source: University Of California - Irvine Date: 2004-07-20

That's a news article, not a research article. But at least it mentions the names of one of the researchers (Haier), so I'll have to look up what they've published (sounds like it's available in NeuroImage, which I have access to).


I haven't had a chance to read the article, but I wonder why anyone would still be looking at head circumference, when we have a means of measuring brain volume and now a means of measureing the volumes of those small parts of the brain that contribute to intelligence?

They didn't just measure head circumference. They measured brain volume as well, and even broke it down further by size of some other brain regions. They used head circumference because it is an easy measure that is related to malnutrition during infancy and early childhood and were looking to see if it was a consistent predictor of brain volume and IQ.

Some brain and head size related factoids:

The average female brain is smaller than the average male brain. This is true, even after the size difference is corrected for relative differences in body size. The average male brain is about 12.5% heavier.

The average female brain has more neurons per unit volume than the average male brain (about 11%).

Much of this difference is well-established as relating to areas involved in sexual behavior, reproductive function, maternal behavior. Besides, the two facts you present together don't indicate any difference in neuronal number, just that the density of neurons is greater in women than men, so their brains are more compact. This is far too simplistic though, since there are some brain areas that are larger in women than men. It relates to gender-specific brain functions.

The average brain and head size is smaller for blacks than for whites.

Based on the article I cited above, this would indicate we should be seriously looking into the extent of malnutrition among the black population in the US, especially in pre-school aged children, since it seems nutritional interventions for school-aged children may be too late to help.

The number of neurons in the brain is fixed by age 4, but the brain size to intelligence correlation is weak at age 4. By age 7 there is a significant within family effect. Miller argues that this is consistent with his myelination hypothesis because myelination of the brain is not significant at age 4, but is much more so at 7 and continues through adolescence.

We now know that there is remarkable plasticity in both neuronal numbers and connections in adults. Adults still have neuronal stem cells capable of producing new neurons (this has only really come to light within probably the last 5 years or so). It used to be believed that once we hit adulthood, we could only lose brain cells, not grow new ones, but that has been completely overturned.

The myelination hypothesis seems to be in contradiction to the summary you posted of work by Haier's group, which stated that it was gray matter volume that is important to IQ. Gray matter is gray because it is unmyelinated. Though, white matter and gray matter are pretty archaic terms.

The correlation between body size and brain size in adults is between .20 and .25.

The correlation between head size and IQ ranges from .10 to .25 (various studies), with a mean of .15.

The correlation (one study only) between head size and _g_ is .30.

The correlation between brain size, as measured by MRI, and IQ is .40 (corrected for body size).

What statistic is being used for these correlations? I'm accustomed to correlations being reported as an r-value, where 0 is no correlation and 1 is a high correlation. Any correlation near 0.5 would be pretty equivocal, and something as close to zero as .1 or .2 would mean there is no correlation at all. In either case, correlation does not mean causation, it may mean both are affected by the same causational event, such as prolonged childhood malnutrition. In combination with the article on folate levels (the other thread of that topic) and IQ, this may all be attributable to a difference in metabolism that requires an even higher level of intake of certain nutritients than we are teaching the public is required for being healthy.

[Evo]

There is no requirement that a psychometrician hold a particular university degree. This is especially so because the field of psychometrics is quite removed from much of psychology and makes particularly heavy demands on statistical knowledge and laboratory research. The thing that distinguishes a psychometrician (or other specialist) is his devotion to the subject at hand, years of study, years of research, and participation in the publication of peer reviewed research. The women you listed are not qualified to peer review psychometric research.So, regardless of a person's qualifications, you won't believe them unless they are a psychometrician, ok, here's a Ph.D. in Psychometrics.

Peter H. Schönemann, Professor Emeritus, Department of Psychological Sciences, Purdue University, Ph.D Illinois, 1964; General Psychology

Ph.D. in psychometrics at the UofI.

Studies the effect of genetics on human behavior. Says genetics play only a small role in intelligence and behavior. Teaches course about intelligence, or IQ, tests. Is opposed to using aptitude tests to predict future success of students.

Here are a few excerpts.

IQ Controversy

(a) Problem of defining "intelligence":

"In his controversial revival of the eugenic traditions of the 20s, Arthur Jensen (1969) appealed explicitly to Spearman's factor model as a vehicle for defining "intelligence". However, in view of the factor indetermincay problem (see above, factor analysis), these high hopes are doomed to failure [40, 47, 52, 57, 83] . Recourse to concrete IQ tests is equally unsatisfactory, because different tests are often quite poorly correlated. In fact , this was the reason why Spearman had postulated his factor model in the first place. From a purely pragmatic point of view one further finds that, contrary to what some authors who should know better have claimed, conventional IQ tests are surprisingly poor predictors of most criteria of practical interest, including scholastic achievement. For example, the SAT - a descendent of conventional "verbal" IQ tests such as the Army Alpha - consistently performs worse than easily available previous grades as a predictor of subsequent grades. This was known, though not advertised, since the 20s. For long range criteria (such as graduation or GPA at graduation), the SAT usually accounts for less than 5% of the criterion variance (Humphreys, 1967, Donlon, 1984). As one might expect, the picture dims further for the GRE: In two recent, large scale, validity studies, Horn and Hofer (undated) and Sternberg (1998 ) found that the validities of the GRE for predicting successful completion of graduate training were effectively zero.

This means that no-one knows what "intelligence" is after 100 years of feverish "research". This is especially disconcerting if viewed against the historical background of the mental test movement which Jensen and his followers have tried to revive by linking untenable validity claims for IQ to equally specious "heritability" claims (see Quantitative Behavior Genetics, below)..

Thus, Spearman's Hypothesis does not warrant any of the farreaching claims Jensen and some of his followers (e.g., Herrnstein and Murray) have attached to it. In particular, it does not validate the existence of a general ability g as Jensen has asserted. Nor does it have any bearing on the race question."

Quantitative Behavior Genetics

"One reason for the astonishing persistence of the IQ myth in the facce of overwhelming prior and posterior odds against it may be the unbroken chain of excessive "heritability" claims for "intelligence", which IQ tests are supposed to "measure". However, if "intelligence" is undefined, and Spearman's g is beset with numerous problems, not the least of which is universal (and by now tacitly though grudgingly acknowledged) rejection of Spearman's model by the data, then how can the heritability of "intelligence" exceed that of milk production of cows and egg production of hens?

These problems are addressed in a series of more recent publications, [54, 60, 61, 62, 63, 70, 71, 72, 75, 81]. In [70] it is shown that a once widely used "heritability estimate" is mathematically unsound, because Holzinger had made a mistake in his derivations which had been overlooked for decades. Another such estimate, though mathematically valid, never fits any real data. This should have been obvious from the start because it typically produces an inordinate number of inadmissible estimates (e.g., proportions larger than 1). These absurd results nevertheless found their way into print without comment or challenge. The same estimate also produces excessive "heritabilities" for variables which plainly have nothing to do with genes. For example, the "heritability" of answers to the question: "Did you have your back rubbed last year?" turns out to be 92% for males and 21% for females [81].

The main problem is that all such estimates rely on simplistic mathematical models which necessarily make some unrealistically stringent assumptions. Unfortunately, they were rarely tested. Once they are tested, one finds that they are usually violated by the data. A comprehensive review of these issues is attempted in [81], where further references to specific subproblems can be found. "

Complete information can be found here http://www.psych.purdue.edu/~phs/research.htm

[Mandrake]

They didn't just measure head circumference. They measured brain volume as well, and even broke it down further by size of some other brain regions. They used head circumference because it is an easy measure that is related to malnutrition during infancy and early childhood and were looking to see if it was a consistent predictor of brain volume and IQ.
The obvious problem with the use of head circumference as a proxy for brain volume is that it introduces a significant error in estimating brain volume.

Much of this difference is well-established as relating to areas involved in sexual behavior, reproductive function, maternal behavior. Besides, the two facts you present together don't indicate any difference in neuronal number, just that the density of neurons is greater in women than men, so their brains are more compact. This is far too simplistic though, since there are some brain areas that are larger in women than men. It relates to gender-specific brain functions.
Since this subject interests you, I have a few items that pertain to it:
The g Factor: Intelligence, Income, Inequality
by Edward M. Miller
Mankind Quarterly, Vol. 39 (Spring 1999) No. 3, 337-354

It is well established that female brains are smaller than male brains, and also that g correlates with brain size. Thus it is surprising that there is no sex difference in g. Jensen attempts to resolve this by noting that "the sex difference in brain size may be best explained in terms of the greater 'packing density' of neurons in the female brain, a sexual dimorphism that allows the same number of neurons in the male and female brains despite their differences in gross size." (p541). The major problem with this theory is evolutionary, if one can obtain the same performance by packing the neurons closer together, this would presumably save energy and reduce birth difficulties. One naturally asks why such a superior design was adapted for female brains, but not for male brains. Another possibility is that the extra brain matter in males is used for some function males excel at, such as spatial visualization. To me this is far more plausible.
===
Kings of Men: Introduction to a Special Issue of the Journal of INTELLIGENCE (1998)
by DOUGLAS K. DETTERMAN

We now know quite conclusively from MRI studies, for example, that IQ is correlated with brain size, but we still don't know what precisely it is about brain size that causes this correlation.
===
MYOPIA, INTELLIGENCE, AND THE EXPANDING HUMAN NEOCORTEX
[International Journal of Neuroscience (1999), 98(3-4): 153-276]
Precis of Storfer on Brain-Intelligence

Supporting this proposed construct are findings that: (1) in rodents, exposure to an unusual amount of visual complexity (coupled with novelty) induces neuronal enlargement in the expected areas (and layers) of the neocortex, with these postmortem effects heightened with multigenerational exposure; and (2) intellectually gifted people have grossly enlarged neurons in the areas associated with their specific gift or talent (see section 3.3), especially in the cortical layers that interconnect distant association areas (III; V), and the layer between (IV), which connects cortex with thalamus.

It is further proposed that the markedly greater likelihood of females with high IQs having myopia compared with equivalent-IQ males (see section 2.1) reflects the smaller size of the female brain (males have roughly 15% more neocortical neurons, but, interestingly, only a 2% larger thalamus). Since females perform almost as well as males in the two-dimensional spatial-analysis components of IQ tests, it would seem to follow that, to cope with the visual complexity of a modern urban environment, a greater stress would be placed on the female's available neuronal resources. Thus, a proportionately larger visual pathway would be generated in females to accommodate the additional attentional strain.

Based on the article I cited above, this would indicate we should be seriously looking into the extent of malnutrition among the black population in the US, especially in pre-school aged children, since it seems nutritional interventions for school-aged children may be too late to help.

Why so? Your comment implies that malnutrition affects most blacks in the US, but not whites. It doesn't add up, since the W-B IQ gap is largest at the highest SES level and lowest at the lowest SES level. Is malnutrition related to SES? If so, wouldn't it make sense that the higher SES levels would have better nutrition? Likewise, would you support seriously looking at the malnutrition in Hispanics, non-Hispanic whites, and Asians with respect to Ashkenazi Jews? Is it likely that Asians have malnutrition that causes them to have a mean IQ below that of Ashkenazi Jews? If you are unfamiliar with the relative brain size findings this may be helpful:

Is There a Biological Basis for Race and Racial Differences?
By J. Philippe Rushton
Insight, May 28, 2001

What I've found is that in brain size, intelligence, temperament, sexual behavior, fertility, growth rate, life span, crime, and family stability, Orientals fall at one end of the spectrum, blacks fall at the other end and whites fall in between. On average, Orientals are slower to mature, less fertile, and less sexually active, and have larger brains and higher IQ scores. Blacks are at the opposite end in each of these areas. Whites fall in the middle, often close to Orientals.

The relation between brain size and intelligence has been shown by dozens of studies, including state-of-the-art magnetic resonance imaging. Orientals average 1 cubic inch more brain matter than Whites, and Whites average a very large 5 cubic inches more than Blacks. Since one cubic inch of brain matter contains millions of brain cells and hundreds of millions of nerve connections, brain size differences help to explain why the races differ in IQ.

Racial differences in brain size show up early in life as well. The U.S. Collaborative Perinatal Project followed more than 50,000 children from birth to seven years. In the 1997 issue of the journal Intelligence, I showed that these Orientals had larger brains than Whites at birth, four months, one year, and seven years; the Whites had larger brains than Blacks at all ages. In the United States, Orientals are seen as a "model minority." They have fewer divorces, out-of-wedlock births, and fewer reports of child abuse than Whites. More Orientals graduate from college and fewer go to prison. Blacks, on the other hand, are 12% of the American population but make up 50% of the prison population.

Genes play a big part in athletic ability, brain size, IQ, and personality. Trans-racial adoption studies, where infants of one race are adopted and reared by parents of a different race, provide some of the strongest evidence. Oriental children, even if malnourished before being adopted by white parents, go on to have IQs above the white average. Black infants adopted into middle-class white families end up with IQs lower than the white average.

The myelination hypothesis seems to be in contradiction to the summary you posted of work by Haier's group, which stated that it was gray matter volume that is important to IQ. Gray matter is gray because it is unmyelinated. Though, white matter and gray matter are pretty archaic terms.
Ed Miller's hypothesis is based on large numbers of supporting observations, all of which support his neural noise model. He argues that the role of myelination is to reduce the cascading effects of neural noise as the brain sends pulses from one place to another.

What statistic is being used for these correlations? I'm accustomed to correlations being reported as an r-value, where 0 is no correlation and 1 is a high correlation.
A correlation coefficient of 1 is not just high, it is absolute.

Any correlation near 0.5 would be pretty equivocal, and something as close to zero as .1 or .2 would mean there is no correlation at all.
Murray and Herrnstein: "A crucial point to keep in mind about correlation coefficients, now and throughout the rest of the book, is that correlations in the social sciences are seldom much higher than .5 (or lower than -.5) and often much weaker -- because social events are imprecisely measured and are usually affected by variables besides the ones that happened to be included in any particular body of data. A correlation of .2 can nevertheless be "big" for many social science topics. In terms of social phenomena, modest correlations can produce large aggregate effects. Witness the prosperity of casinos despite the statistically modest edge they hold over their customers." [The Bell Curve, page 67]

Another example of small, but meaningful and robust correlations is inbreeding depression. This phenomenon is observed to affect numerous traits, including IQ and is consistently mentioned in psychometric texts as one of the most indisputable proofs of the strong genetic component of intelligence. When inbreeding is very close (siblings or parent-child), the effect is quite large; but most studies are based on first cousins, where effects on physical traits are typically .05 sigma to .10 sigma. [Jensen reports a number of studies pertaining to inbreeding depression in his book The g Factor. See the chapter titled “The Heritability of g.”]

In either case, correlation does not mean causation,
Have there been any suggestions here to the contrary?

[Mandrake]

So, regardless of a person's qualifications, you won't believe them unless they are a psychometrician,
True, when they assert positions that are inconsistent with well established findings. The sources you seek are selected on the basis that they must be left-wing liberal propaganda.

ok, here's a Ph.D. in Psychometrics.
Schönemann is a known quantity. I have read some of his material before. You can believe whatever you wish, but I do not accept his or any other person's assertions when they are simply outrageous. Some of the material you quoted from him is just that. Would you care to explain the error that is supposed to have been made by Holzinger? I assume you understand it (I do not) or you would not have cited it. I await the details.

So, if you were going to hire someone to represent you in court, would you select a psychometrician or a lawyer? Do you understand why this question is related to your recent comments?

[Nereid]

Is ‘psychometrics’ essentially synonymous with ‘(the study of) intelligence’ (per Mandrake), or is it much broader, with the intelligence part being only a minor component?
This page (http://www.fordham.edu/aps/whatpsy.html), from Fordham University re their PhD program in psychometrics, suggests the latter; e.g. "Of course the most obvious area in which psychometricians are employed is in psychological testing. Testing, whether it be of intelligence, personality, achievement, aptitudes, interests, or proficiency, is a widespread and important practice in our society. […]Psychometricians are not limited to working within the testing industry however. Many psychometricians are employed in industrial and organizational settings performing job analyses, consumer surveys, developing and validating personnel selection procedures, and performing market research. Positions in private and public consulting agencies, clinical research positions, and positions in managerial and administrative roles are also open to graduates of psychometric programs." (my emphasis)

Clarification please!

[Nereid]

Suppose I want to know my _g_ and how it may vary. I understand that I can take a test (e.g. an IQ test with high _g_ loading), some chronometric tests, or an EEG. From just one test – of any of these three kinds – what +/- number would my _g_ come with? What is the distribution (e.g. Gaussian)? How does each type of test vary wrt this +/-?

Since _g_ has to do with my brain, and I know all kinds of things affect the performance of ‘brain tasks’, I’m sure psychometricians have done extensive research into the effects of the following on one’s _g_, as estimated by one of the three kinds of _g_ tests:
- alertness, e.g. taking the test mid-morning after a good night’s sleep vs one taken at 2am
- drugs, e.g. caffeine, alcohol, anti-histimines; especially those which are known to affect reaction times and medications for mental conditions
- pain, esp headaches
- general wellness/fitness, e.g. fever, top physical form, hunger,
- brain affecting illnesses or conditions, e.g. epilepsy, depression, Alzheimers, tumour, physical injury, PTSS
- mood
- age

How do estimates of _g_ vary for each of these classes of factors?

(I see that hitssquad has partly answered some of these questions)

[Nereid]

Humans are complex animals, and their behaviour a rich field of study. In medicine, a rather paradoxical but well attested effect is the ‘placebo effect’ – giving someone an injection, or a pill results in an objectively observed difference (from not giving one), even if the contents are otherwise known to have no effect. A slightly less paradoxical effect is the ‘white coat effect’ – e.g. some people’s blood pressure is higher in the presence of a white-coated doctor (or blood pressure equipment).

Tests of _g_ also involve human interaction, either tester with subject or machine with subject.

What has psychometric research – not just in intelligence – shown wrt effects somewhat analogous to the placebo or white coat effects? How does the act of administering a psychometric test affect the subject (either consciously, or, more importantly subconsciously)?

[Nereid]

I was not in the US when the book was published, but my reading seems to indicate it generated quite a deal of controversy. Mandrake has said that it received few, if any, negative reviews of comments from psychometricians. Indeed, the APA’s review had some favourable things to say about its presentation of the generally accepted scientific results.

However, it would seem that the book contained far more than a dispassionate summary of the then status of a field of science – it also talked about social programs, genetics, politics, and a favourite obsession of 20th century US society, race. If so (I’ve not read the book, so I can’t myself comment on how extensive, or impartial, the authors were on these topics), it would seem entirely appropriate for criticisms of the book to be made from any of these perspectives.

How clearly did the book present the scientific results? E.g. how well did the tentative, provisional nature of all science come across? How was the study of intelligence (a branch of psychology) contextualised wrt neuroscience? Biology? Genetics? Other parts of psychology?

Around the time of the publication of the book, some 50 people signed their names to an ad in a leading US newspaper, on race and intelligence (if memory serves). IIRC, all but four were at US academic institutions. How many were active psychometricians? In the psychometric field of intelligence studies? At the time, how many professional psychometricians were there in US academic institutions?

[hitssquad]

Since _g_ has to do with my brain, and I know all kinds of things affect the performance of ‘brain tasks’, I’m sure psychometricians have done extensive research into the effects of the following on one’s _g_, as estimated by one of the three kinds of _g_ tests:
- drugs, e.g. caffeine, alcohol, anti-histimines; especially those which are known to affect reaction times and medications for mental conditionsReaction time is composed of decision time and motor time. Caffeine may affect motor time, but AFAIK it has not been shown to affect decision time. Other drugs such as Bacopa Monniera (AKA the ayervedic herb Brahmi) may affect decision time, as Bacopa itself has been shown (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11498727) to affect the related variable inspection time and has been shown to increase g (as measured by standard psychometric batteries in a controlled study).



- ageg is known to smoothly drop in adults with age, as I have mentioned many times on Physics Forums and which I mentioned many times as a raison d'être for anti-senescence efforts.

This page has a nice graph of what is likely happening to you as you read this:
http://hiqnews.megafoundation.org/Definition_of_IQ.html

Age-related cognitive decline is also being discussed (http://www.childrenofmillennium.org/phpBB2/viewtopic.php?t=50) over at the Children of Millennium forums:


As you age beyond the age of 18, your physical brain-decay (glycoxidation; amyloid beta build-up; mitochondrial damage; DNA damage) can be clearly watched in slow motion in the form of your raw scores predictably dropping point by point, year by year.

IQ scores on IQ tests correct for this post-18 brain rot, and you are given a same-age-peers curve-graded IQ score (in addition to being allowed to cheat with a massively-larger vocabulary than your g would otherwise imply -- boosted vocabulary subtest scores via vocab cheating by oldsters on the Weschler averages +.80 S.D. {and that's not counting the other free full-scale IQ points they get because their peers have physical brain rot}, according to a brand new study {see at the bottom of this post Verhaeghen; see also MacLullich, et al}).

[nuenke]

I came across a recent study that looks at intelligence and specific areas or patches of gray matter. They did not do a correlation as such, but it does look like they are locating those areas related to g, as well as other factors like fatty tissue around axons, glucose uptake, etc. But at least the IQ vs. Brain size is getting narrowed down to IQ and specific brain reqions.

[Nereid]

The APA report addresses some issues quite well; it addresses others incompletely; and it misrepresents some issues. Consider the discussion about heritability. They discuss only MZA data and say nothing about path analysis. Why? The results are in agreement, but the literature claims are that path analysis is more robust. In this area, they had no way of knowing what would later be discovered by Dr. Paul Thompson at UCLA: "We were stunned to see that the amount of gray matter in frontal brain regions was strongly inherited, and also predicted an individual's IQ score..." His work was done with MRI. Their coverage of the Scarr-Weinberg findings was poor.It seems that there may be more than one 'APA report'; could someone please tell me whether this (http://www.apa.org/releases/intell.html) is the one we're discussing?

"APA Task Force Examines the Knowns and Unknowns of Intelligence

1996 Press Release
What is intelligence and can it be measured? These questions have fueled a continuing debate about whether intelligence is inherited, acquired, environmental, or a combination of these and other factors. In a field where so many issues are unresolved and so many questions unanswered, the confident tone that has characterized most of the debate on these topics is clearly out of place, according to a new report by the American Psychological Association (APA).

The report, entitled 'Intelligence: Knowns and Unknowns,' was written by APA's Task Force on Intelligence. The task force convened in January 1995 to prepare a dispassionate and authoritative report in response to the fall 1994 publication of Herrnstein and Murray's The Bell Curve. 'Their book sparked a new and vigorous round of debate about the meaning of intelligence test scores and the nature of intelligence itself, a debate in which little effort was made to distinguish scientific issues from political ones,' stated Ulric Neisser, PhD, chair of the task force.

Because there are many ways to be intelligent, there are also many conceptualizations of intelligence. Standardized intelligence test scores (IQs), which reflect a person's standing in relation to his or her generational peers, are based on tests that measure a number of different abilities. Psychometric testing, the use of standardized tests to assess specific abilities, has generated the most systematic research though many questions remain unanswered. According to the task force report:

* Intelligence test scores partially predict individual differences in school achievement, such as grade point average and number of years of education that individuals complete. In this context, the skills measured are important. Nevertheless, population levels of school achievement are not determined solely or even primarily by intelligence or any other individual-difference variable. The fact that children in Japan and Taiwan learn much more math than their peers in America, for example, can be attributed primarily to differences in culture and schooling rather than in abilities measured by intelligence tests.

* Test scores also correlate to some extent with measures of accomplishment outside of school, for example adult occupational status. This correlation is linked with school achievement because, in the United States today, high test scores and grades are prerequisites for entry into many careers and professions. However, a significant correlation between test scores and occupational status remains even when education and family background have been statistically controlled.

* Differences in genetic endowment contribute substantially to individual differences in (psychometric) intelligence, but the pathway by which genes produce their effects is still unknown. The impact of genetic differences appears to increase with age, but it is not known why.

* Environmental factors contribute substantially to the development of intelligence, but it is not clearly understood what those factors are or how they work. Attendance at school is certainly important, for example, but it is not known what aspects of schooling are critical.

* The role of nutrition in intelligence remains obscure. Severe childhood malnutrition has clear negative effects, but the hypothesis that certain 'micro- nutrients' may affect intelligence in otherwise adequately-fed populations has not been convincingly demonstrated.

* The differential between the mean intelligence test scores of Blacks and Whites does not result from any obvious biases in test construction and administration, nor does it simply reflect differences in socio-economic status. Explanations based on factors of caste and culture may be appropriate, but so far there is little direct empirical support for them. There is certainly no such support for a genetic interpretation. At this time, no one knows what is responsible for the differential.

* It is widely agreed that standardized tests do not sample all forms of intelligence. Obvious examples include creativity, wisdom, practical sense, and social sensitivity, among others. Despite the importance of these abilities, very little is known about them, how they develop, what factors influence their development, and how they are related to more traditional measures.

* Although there are no important sex differences in overall intelligence test scores, substantial differences do appear for specific abilities. Males typically score higher on visual-spatial and (beginning in middle childhood) mathematical skills; females excel on a number of verbal measures. Sex hormone levels are clearly related to some of these differences, but social factors presumably play a role as well.

The task force distinguishes sharply between scientific research and political rhetoric. 'The study of intelligence does not need politicized assertions and recriminations; it needs self-restraint, reflection, and a great deal more research.' According to the report, the questions that remain are socially as well as scientifically important and 'that there is no reason to think them unanswerable, but finding the answers will require a shared an sustained effort as well as the commitment of substantial scientific resources.'

The American Psychological Association (APA), in Washington, DC, is the largest scientific and professional organization representing psychology in the United States and is the world's largest association of psychologists. APA's membership includes more than 132,000 researchers, educators, clinicians, consultants and students. Through its divisions in 49 subfields of psychology and affiliations with 58 state and territorial and Canadian provincial associations, APA works to advance psychology as a science, as a profession and as a means of promoting human welfare.

[Nereid]

High g Loading
Matrix relations (.94)
Generalizations (.89)
Series completion (.87)
Verbal analogies (.83)
Likeness relations (.77)
Problem arithmetic (.77)
Paragraph comprehension (.73)
Perceptual analogies (.70)

[...]

[list]The knowledge and skills tapped by mental test performance merely provide a vehicle for the measurement of g. Therefore, we cannot begin to fathom the causal underpinning of g merely by examining the most highly g-loaded psychometric tests.(Ibid (http://www.questia.com/PM.qst?a=o&d=24373907). p74.)If 'matrix relations' tests have a _g_ loading of 0.94, what else is there is in these tests? In well constructed matrix relations tests, what is the typical individual variance (i.e. an individual takes the same (type of) test many times)?

[Nereid]

Contrarily, research has demonstrated that:

There are plausible reasons ... for assuming that individual differences in g have an approximately normal, or Gaussian ("bellshaped"), distribution, at least within the range of ±2σ from the mean. That range is equivalent to IQs from 70 to 130 on the typical IQ scale (i.e., μ = 100, σ = 15).(Arthur Jensen. The g Factor (http://www.questia.com/PM.qst?a=o&d=24373907). p88.)Does Jensen go on to say what those 'plausible reasons' are? Subsequent to when Jensen wrote this, what research has been done to establish what that distribution actually is? Why did Jensen add the caveat "within the range of ±2σ from the mean"?

[Nereid]

Based on the article I cited above, this would indicate we should be seriously looking into the extent of malnutrition among the black population in the US, especially in pre-school aged children, since it seems nutritional interventions for school-aged children may be too late to help.Why so? Your comment implies that malnutrition affects most blacks in the US, but not whites. It doesn't add up, since the W-B IQ gap is largest at the highest SES level and lowest at the lowest SES level. Is malnutrition related to SES? If so, wouldn't it make sense that the higher SES levels would have better nutrition? Likewise, would you support seriously looking at the malnutrition in Hispanics, non-Hispanic whites, and Asians with respect to Ashkenazi Jews? Is it likely that Asians have malnutrition that causes them to have a mean IQ below that of Ashkenazi Jews?Where to begin to untangle this?

For a start, sentences in English with comparatives ('most', 'higher') don't help IMHO; the reality of population groups is very rich, and teasing apart the influences of multiple factors calls for hard thought.

Take the Black and White SES: if early childhood malnutrition contributes, then you would need to know about the relative experiences of groups who are now in their 40s to 60s. Cet par it may very well be that 'the higher SES levels would have better nutrition', but my impression is that in 21st century US society things are most certainly not otherwise equal.

Take Asians: my impression is that a significant proportion of Asians in the US are migrants or children of migrants; further, with some notable exceptions, they are primarily 'economic migrants' - they made conscious choices and effort to migrate. In this sense, the 'control group' of whites would be those who arrived in the US several centuries ago (and there'd be no black control group; unless I have misread my US history, most folk who came from Africa didn't make get a choice).is anything If you are unfamiliar with the relative brain size findings this may be helpful:

Is There a Biological Basis for Race and Racial Differences?
By J. Philippe Rushton
Insight, May 28, 2001

What I've found is that in brain size, intelligence, temperament, sexual behavior, fertility, growth rate, life span, crime, and family stability, Orientals fall at one end of the spectrum, blacks fall at the other end and whites fall in between. On average, Orientals are slower to mature, less fertile, and less sexually active, and have larger brains and higher IQ scores. Blacks are at the opposite end in each of these areas. Whites fall in the middle, often close to Orientals.

The relation between brain size and intelligence has been shown by dozens of studies, including state-of-the-art magnetic resonance imaging. Orientals average 1 cubic inch more brain matter than Whites, and Whites average a very large 5 cubic inches more than Blacks. Since one cubic inch of brain matter contains millions of brain cells and hundreds of millions of nerve connections, brain size differences help to explain why the races differ in IQ.

Racial differences in brain size show up early in life as well. The U.S. Collaborative Perinatal Project followed more than 50,000 children from birth to seven years. In the 1997 issue of the journal Intelligence, I showed that these Orientals had larger brains than Whites at birth, four months, one year, and seven years; the Whites had larger brains than Blacks at all ages. In the United States, Orientals are seen as a "model minority." They have fewer divorces, out-of-wedlock births, and fewer reports of child abuse than Whites. More Orientals graduate from college and fewer go to prison. Blacks, on the other hand, are 12% of the American population but make up 50% of the prison population.

Genes play a big part in athletic ability, brain size, IQ, and personality. Trans-racial adoption studies, where infants of one race are adopted and reared by parents of a different race, provide some of the strongest evidence. Oriental children, even if malnourished before being adopted by white parents, go on to have IQs above the white average. Black infants adopted into middle-class white families end up with IQs lower than the white average. I trust this is a piece of journalism and not a scientific paper; I sincerely hope that Rushton has done good science to back each of the points he makes here. In particular, I would expect that he has done studies in other countries, to demonstrate (for example) that he's not just reporting on some unique, US, human condition.

[Mandrake]

Suppose I want to know my _g_ and how it may vary. I understand that I can take a test (e.g. an IQ test with high _g_ loading), some chronometric tests, or an EEG. From just one test – of any of these three kinds – what +/- number would my _g_ come with? What is the distribution (e.g. Gaussian)? How does each type of test vary wrt this +/-?

Since most observers do not have the laboratory devices and skills to measure intelligence via chronometric or electroencephalography techniques, the most common approach is to use an IQ test. As you probably know there are very many IQ tests, although only a few of them are used in most serious research. Of these the Raven's is most often cited in research programs. The WAIS versions are also widely used. For most tests, _g_ has to be extracted by weighting the subtest scores according to their _g_ loadings. Obviously, different tests will have different _g_ loadings, different subtest structures, and different associated errors. As with measuring physical phenomena (consider temperature) there are errors that can be identified in connection with many aspects of the measurement. Most of these errors are small. Ultimately the reliability coefficient is of central importance. Jensen: "The difference between the reliability coefficient and unity represents the proportion of the total variance of the measurements that is attributed to measurement error. ... In my laboratory we have been able to measure such variables as memory span, flicker-fusion frequency (a sensory threshold), and reaction time with reliability coefficients greater than .99. ... The reliability coefficients for multi-item tests of more complex mental processes, such as measured by typical IQ tests, are generally about .90 to .95. This is higher than the reliability of people's height and weight measured in a doctor's office! The reliability coefficients of blood pressure measurements, blood cholesterol level, and diagnosis based on chest X-rays are typically around .50." [The _g_ Factor, P. 50]

The concept of TRUE SCORE is related.
Regressed true score = [(reliability coefficient) x (test score - mean score for population)] + (mean score for population)
This is obviously a hypothetical score that attempts to factor out measurement error. For a very detailed discussion of all things related to measurement error, see Jensen, A.R. (1980). Bias in mental testing. New York: Free Press. Jensen says that tests with reliability coefficients of less than .90 should (generally) not be used.



Since _g_ has to do with my brain, and I know all kinds of things affect the performance of ‘brain tasks’, I’m sure psychometricians have done extensive research into the effects of the following on one’s _g_, as estimated by one of the three kinds of _g_ tests:
- alertness, e.g. taking the test mid-morning after a good night’s sleep vs one taken at 2am
- drugs, e.g. caffeine, alcohol, anti-histimines; especially those which are known to affect reaction times and medications for mental conditions
- pain, esp headaches
- general wellness/fitness, e.g. fever, top physical form, hunger,
- brain affecting illnesses or conditions, e.g. epilepsy, depression, Alzheimers, tumour, physical injury, PTSS
- mood
- age

How do estimates of _g_ vary for each of these classes of factors?

I don't have a source at hand with a ready answer. When an IQ test is given, it is the responsibility of the test administrator to determine that the person taking the test is fully alert and not encumbered by factors that would render the test inaccurate. Some tests, such as the WAIS are age adjusted.

[Mandrake]

Nereid:
What has psychometric research – not just in intelligence – shown wrt effects somewhat analogous to the placebo or white coat effects? How does the act of administering a psychometric test affect the subject (either consciously, or, more importantly subconsciously)?
There are various papers that have examined the conditions of test taking. The range of things considered includes, for example, stress. Jensen used pulse rate to measure stress, but found that it did not significantly affect scores. A placebo effect would imply that something causes the person taking the test to score artifically high. I am unaware of any such finding. There are also various reports that such things as stimulants or even music can temporarily boost test scores. Presumably these findings indicate an induced error in the positive direction, since no findings have reported permanent improvements in intelligence due to such factors.

[Mandrake]

I was not in the US when the book was published, but my reading seems to indicate it generated quite a deal of controversy.
There were a lot of people who were unaware of the findings reported in The Bell Curve. When I saw it, I was amazed to see that virtually every item in it had been previously reported in even greater detail. It was basically old science, but suddenly hit uninformed people in the face. Instead of trying to understand it, they reacted by writing ignorant missives in newspapers and magazines.

The Bell Curve can be divided into three parts:
1 - a detailed summary of history, research findings, and theories (including some of the unsound ones)
2 - an analysis of the National Longitudinal Study of Youth
3 - a discussion of the social and economic impacts that may relate to 1 and

If so (I’ve not read the book, so I can’t myself comment on how extensive, or impartial, the authors were on these topics), it would seem entirely appropriate for criticisms of the book to be made from any of these perspectives.
It is fair to argue item 3 forever. People have different views. Items 1 and 2 are matters of science and, if they are to be disputed, must be disputed on scientific grounds, not emotional ones. The basic rant that came from journalists was something to the effect that god made all men equal and, therefore, they must all be equally intelligent. Some people even cited the Declaration of Independence to demonstrate that blacks do not have a mean IQ of 85.

How clearly did the book present the scientific results?
Very clearly and very carefully. Most of items 1 and 2 were understated and supported by massive parallel findings. That is to say that to make a simple point, the authors cited findings from many independent studies, different countries, and different time frames, all reaching the same conclusion. In instances where there were conflicting findings, they clearly stated so. The book was written in a form that made it easy to read, by comparison to the typical Jensen text books.

E.g. how well did the tentative, provisional nature of all science come across?
The book was not intended to address all science and it did not. It was also not a general discussion of philosophy.

How was the study of intelligence (a branch of psychology) contextualised wrt neuroscience? Biology? Genetics? Other parts of psychology?
These issues were discussed to the degree that was possible one decade ago. There have been important findings since that time, especially in connection with laboratory measurements. Jensen, A. R. (1998). The g factor: The science of mental ability. Westport, CT: Praeger is a much better present day reference book.

Around the time of the publication of the book, some 50 people signed their names to an ad in a leading US newspaper, on race and intelligence (if memory serves).
The newspaper was the Wall Street Journal, Tuesday, December 13, 1994. The letter it printed was written by Linda Gottfredson, although it was not attributed to her. It was signed by, as I recall, 52 scholars.

IIRC, all but four were at US academic institutions.
Close. I just counted six. Detterman reported (in Intelligence) the details of how, why, and under what conditions that letter was written. There are very good reasons behind its final form and the people who signed it.

How many were active psychometricians? In the psychometric field of intelligence studies? At the time, how many professional psychometricians were there in US academic institutions?

To the best of my knowledge all of them, but I haven't looked up the lesser known people.

[Mandrake]

Does Jensen go on to say what those 'plausible reasons' are? Subsequent to when Jensen wrote this, what research has been done to establish what that distribution actually is? Why did Jensen add the caveat "within the range of ±2σ from the mean"?

This subject is discussed in much more detail in Bias in Mental Testing, Chapter 4. For example, Jensen wrote: "The simple fact is that a test unavoidably yields a near normal distribution when it is made up of (1) a large number of items, (2) a wide range of item difficulties, (3) no marked gaps in item difficulties, (4) a variety of content or forms, and (5) items that have a significant correlation with the sum of all other item scores, so as to ensure that each item in the test measures whatever the test as a whole measures." He goes on to point out that it would take a lot of effort to produce a test that is so screwed up that it would not produce a distribution that "departs at all radically from the normal."

[hitssquad]

The newspaper was the Wall Street Journal, Tuesday, December 13, 1994. The letter it printed was written by Linda Gottfredson,How many were active psychometricians? In the psychometric field of intelligence studies? At the time, how many professional psychometricians were there in US academic institutions?To the best of my knowledge all of them, but I haven't looked up the lesser known people.Gottfredson is a sociologist (http://www.google.com/search?q=linda+gottfredson+sociologist).

[selfAdjoint]

This subject is discussed in much more detail in Bias in Mental Testing, Chapter 4. For example, Jensen wrote: "The simple fact is that a test unavoidably yields a near normal distribution when it is made up of (1) a large number of items, (2) a wide range of item difficulties, (3) no marked gaps in item difficulties, (4) a variety of content or forms, and (5) items that have a significant correlation with the sum of all other item scores, so as to ensure that each item in the test measures whatever the test as a whole measures." He goes on to point out that it would take a lot of effort to produce a test that is so screwed up that it would not produce a distribution that "departs at all radically from the normal."

THis fact is behind the expectation of geneticists that the genetic component of g is produced by many genes. If there were just one, or a few, the different phenotypes would line up in discrete bunches, rather than a continuous distribution such as is found with sufficiently large populations.

[Mandrake]

Where to begin to untangle this?
My suggestion is a LOT of reading of top quality text books and peer reviewed papers.

For a start, sentences in English with comparatives ('most', 'higher') don't help IMHO; the reality of population groups is very rich, and teasing apart the influences of multiple factors calls for hard thought.

In a discussion forum, such as this one, people can and do provide quotes and links, but cannot reasonably be expected to produce the necessary volume of information that would be required to detail research procedures, error analysis, multiple confirmations, etc. Unfortunately there are people who jump to the conclusion that all of the research that has been done was either done with malice (to discredit stupid people) or with incompetence. Neither is true. In the case of SES comparisons, there have been a lot of studies reported by very capable scientists. The details of their comparisons are not secret. Virtually all comparisons are made with an attempt to remove as many variables as possible. For example, you will find that in The Bell Curve many of the W-B comparisons are done for cohorts with identical IQs. If you examine the past few issues of Intelligence you will find data comparing job status by IQ deciles (I previously quoted it and do not wish to look it up again, but it favors blacks). In the US blacks above the 40th percentile earn more than whites of equal IQ.

In the case of SES, the issue is complex primarily because IQ causes SES and not vice versa. This point may not be a happy finding for some people, but it is well documented in The _g_ Factor. A discussion of SES as it pertains to IQ may also be found in The Bell Curve, starting on page 286.

The issue of malnutrition is obviously a canard in the US. The IQ gap exists for all SES groups and we all know that we do not have a nation of malnourished blacks and properly nourished whites. The cause if the intelligence gap is largely genetic. The entire environmental contribution to IQ is in the range of 20-30%, but that is an overstatement that assumes no error. The strong evidence of IQ and more importantly of _g_ heritability continues to pile up even more now that we have brain imaging. We can actually see the huge overlap between identical twin brains and the sharp reduction when brains of DZ twins are imaged. We have path analysis and MZA studies, both of which show nearly identical values in the 70-75% range. We have detailed inbreeding depression studies that are based on heritability, with measurements matching predictions. We have adoption studies showing virtually no family influence, no correlation between adoptees and their adoptive siblings, and all of these kids turn out to have IQs in the range of their not-adopted peers and in the range predicted by knowing the IQs of the biological parents. We have nutrition studies, showing that even famine does not affect the IQs of children born to malnourished mothers. This is not Ethiopia.

Take Asians: my impression is that a significant proportion of Asians in the US are migrants or children of migrants; further, with some notable exceptions, they are primarily 'economic migrants' - they made conscious choices and effort to migrate.
So, just look at the IQ measurements of Asians who were born in Asia and who still live there. I don't see your point. That data is not missing. I previously commented that Asians in Asia test the same as Asians in the US. Asians adopted in the US and Europe turn out to have IQs higher (this is all statistical, as I hope you know) that their adoptive families.

Is There a Biological Basis for Race and Racial Differences?
By J. Philippe Rushton
Insight, May 28, 2001

I trust this is a piece of journalism and not a scientific paper; I sincerely hope that Rushton has done good science to back each of the points he makes here. In particular, I would expect that he has done studies in other countries, to demonstrate (for example) that he's not just reporting on some unique, US, human condition.
Rushton is a serious and respected scientist. He has published extensively in scientific journals and has conducted research internationally. He is a member of ISIR. Here is a list of his publications:
http://www.ssc.uwo.ca/psychology/faculty/rushton_pubs.htm

[selfAdjoint]

The issue of malnutrition is obviously a canard in the US.

But other physiological conditions have not been completely ruled out. Birth weight for example. Low birth weight is correlated with lower IQ scores in later life, and US blacks have systematically lower birth weights than whites. This gap persists into the more middle class communities too, so it isn't just a diet thing. Of course birth weight could have a large genetic component too, but it is at least ameliorable.

[Mandrake]

Gottfredson is a sociologist (http://www.google.com/search?q=linda+gottfredson+sociologist).

I assume you are familiar with her significant contributions to the literature of psychometrics. I discussed the academic requirements that I believe are appropriate for a psychometrician in a recent message here. She meets all of them. We have people who are outstanding psychometircians who hold degrees in various fields. Her work in recent years has been almost exclusively with respect to intelligence:
http://www.udel.edu/educ/gottfredson/reprints/

Her work with respect to education and teaching is focused on intelligence testing. She and Robert Gordon have produced the best papers available on the subject of the importance of intelligence in everyday life.

[hitssquad]

Does Jensen go on to say what those 'plausible reasons' are?16. Nothing of fundamental empirical or theoretical importance is revealed by the frequency distribution per se of the scores on any psychometric test composed of items. This is true regardless of whether we are dealing with raw scores or standardized scores or any otherwise transformed scores. Therefore, it would be trivial and pointless to review the empirical test literature regarding the form of the distribution of mental test scores.

In a given population, the form of the distribution of raw scores (i.e., number of items passed) is entirely a function of three interrelated item characteristics: (1) the average probability of getting the correct answer by chance, i.e., by pure guessing, (2) the average level of difficulty of the items (as indexed by the percentage of the population that fails them), and (3) the average correlation between items. Item difficulty is completely under the test constructor's control. Score increments due to chance guessing are a function of the number and quality of the alternatives in multiple-choice items and the nature of the instructions to subjects regarding the penalty for guessing at the answer instead of omitting response when uncertain (e.g., total score based on number of right minus number of wrong answers). The item intercorrelations can be controlled to a considerable degree (but never completely) through item selection. Hence, in constructing a test it is possible, within broad limits, to produce almost any desired form of frequency distribution of the raw scores in a given population.

If we have no basis for arguing that the obtained scores have true measurement properties in addition to merely having a rank-order correlation with the latent trait that they measure--and this seems to be typically the case for psychometric test scores--the precise form of the obtained score distribution is essentially arbitrary. The very most that we can say in this case is that (within the limits of measurement error) our test scores have some monotonic relation to whatever the test really "measures." If we could truly measure whatever latent variable, such as g, accounts for the variation in the obtained scores on an absolute scale (i.e., one having a true zero and additivity of scale intervals), the form of its population distribution could turn out to be quite different from that of the test scores we have actually obtained.

Certain forms of distribution are simply more useful than others, psychometrically and statistically, and it is this consideration that mainly determines the form of the distribution test constructors decide to adopt. The aims of maximizing the statistical discriminability of scores throughout a fairly wide range of talent and of obtaining a fair degree of internal consistency reliability (i.e., interitem correlation) are what largely dictate item selection. The test scores that result under these conditions of item selection typically (and necessarily) have a symmetrical and more-or-less "bell-shaped" frequency distribution. It is not truly the normal (or Gaussian) curve, although it usually resembles it closely. By juggling item characteristics the test constructor can get a distribution that reasonably approximates the normal curve. Or the scores can be transformed mathematically to approximate a normal distribution. (Such "normalized" scores are obtained by converting the raw scores to ranks, then converting these to percentile ranks, and then, by reference to a table of the areas under the normal curve, converting these to normal deviates, i.e., normalized z scores.) The reason for thus normalizing a score distribution is not mainly theoretical, but statistical. The normal curve has certain mathematical properties that make it extremely useful in statistical analysis and interpretation.

The argument is often made on theoretical grounds, however, that the main latent trait reflected by most complex cognitive tests--namely g--should be normally distributed in the general population. This argument, if accepted, justifies and indeed demands that IQs (or any other type of scores on any highly g-loaded tests) should be purposely scaled so that the form of their population distribution closely approximates the normal distribution. What can be said for this argument? There are three main facets:

First, there is the argument by default: Unless there is some compelling reason to suppose that the form of the distribution of g is something other than normal, we might as well assume that it is normal, which is at least statistically convenient.

Second, there is the argument from the Central-Limit Theorem in mathematical statistics, which essentially states that the distribution of a composite variable representing the additive effects of a number of independent elements (components, causes, or influences) rapidly approaches the normal distribution as the number of elements increases. This should be the case for g, to the extent that we can argue on various theoretical and empirical grounds that individual differences in g are the result of a great many different additive effects: for example, individual differences in the efficiency of a number of different cognitive processes, each of which is somewhat independently conditioned by polygenic inheritance interacting with a multitude of different environmental influences encountered throughout the course of development since the moment of conception. The population distribution of any variable with such multiple additive determinants, theoretically, should approximate the normal curve.

Third, there is the argument by analogy with human characteristics that actually can be measured on an absolute scale, such as height, brain weight, neural conduction velocity, sensory acuity, choice reaction time, and digit span memory (i.e., the number of digits that can be recalled entirely correctly after one presentation on 50 percent of the trials). We may reasonably presume that individual differences in each of these variables has multiple determinants, just as in the case of g. Indeed, we find that in very large samples of the general population the distribution of each of these variables (measured on an absolute scale) approximates the normal curve. Marked deviations from the normal curve usually occur in the regions beyond ±2σ from the mean of the distribution. These deviations from normality can usually be explained in terms of certain rare genetic or environmental effects that override the multiple normal determinants of variation. This line of argument by analogy makes it quite plausible that g (or any other complexly determined trait) is normally distributed, but it cannot prove it. Also, the argument by analogy is weakened by the fact that not all complexly determined biological variables that can be measured on an absolute scale necessarily conform to the normal distribution. Age at death (beyond five years), for example, has a very negatively skewed distribution, because the mode is close to 75 years and the highest known limit of human longevity is about 113 years. (Below age five, the age of death is distributed as a so-called J curve, with the mode immediately after birth.)

Fourth, the assumption of a normal distribution of g reveals a remarkable consistency between various population groups that show a given mean difference (in σ units) on highly g-loaded tests, such as IQ tests. By knowing the means and standard deviations of two population groups on such a measure, and by assuming that the latent trait, g, reflected by the measurements has a normal distribution in each group, one can make fairly accurate estimates of the percentages of each group that fall above or below some criterion that is not measured by any psychometric technique but is known to be correlated with g to some extent, such as number of years of education, occupational level, or as being judged by nonpsychometric criteria as mentally retarded or as intellectually gifted. Even though these percentages may vary widely from one criterion to another, when the percentages are transformed to normal deviates (obtained from tables of the normal curve), the differences between the groups' normal deviates on various g-related criteria show a considerable degree of constancy. This could not happen if the distribution of g were not approximately normal.

Probably the best answer at present concerning the distribution of g is that, although we cannot determine it directly by any currently available means, it is a reasonable inference that it approximates the normal curve and there is no good reason for assuming that the distribution of g is not approximately normal, at least within the middle range of about four standard deviations. Most psychometricians implicitly work on the statistically advantageous assumption of normality, and no argument has yet come forth that it is theoretically implausible or adversely affects any practical uses of g-loaded tests. But the question is mainly of scientific interest, and a really satisfactory answer to it cannot come about through improved measurement techniques per se, but will become possible only as part and parcel of a comprehensive theory of the nature of g. If we have some theoretical conception of what the form of the distribution should be in a population with certain specified characteristics, we can use random samples from such a population to validate the scale we have devised to measure g. The distribution of obtained measurements should conform to the characteristics of the distribution dictated by theoretical considerations.(Arthur Jensen. The g Factor (http://www.questia.com/PM.qst?a=o&d=24373907). pp101-103.)

[Moonbear]

I just wanted to share that the work done by Haier and co-workers and mentioned by Mandrake has just been published in this month's NeuroImage journal. What struck me as I read the article was the lack of similarity between the younger college-aged subjects and the older middle-aged subjects. Though, as they note, comparisons between the two groups are difficult because different machines were used for the two groups (two different institutions were involved in recruiting the volunteers and performing the imaging). However, if that much variation could be due to just the machines being used, it doesn't seem like a very promising technology. I think they were doing a bit of hand-waving with that explanation. I don't see any comments section with this journal, but I'd be curious to see if any are published in the next issue from people with expertise in imaging. They did break down regions pretty specifically...this certainly is interesting technology if nothing else.

NeuroImage 2004, 23: 425-433
Structural brain variation and general intelligence
Haier RJ, Jung RE, Yeo RA, Head K, Alkire MT

Total brain volume accounts for about 16% of the variance in general
intelligence scores (IQ), but how volumes of specific regions-of-interest
(ROIs) relate to IQ is not known. We used voxel-based morphometry
(VBM) in two independent samples to identify substantial gray matter
(GM) correlates of IQ. Based on statistical conjunction of both samples
(N = 47; P < 0.05 corrected for multiple comparisons), more gray
matter is associated with higher IQ in discrete Brodmann areas (BA)
including frontal (BA 10, 46, 9), temporal (BA 21, 37, 22, 42), parietal
(BA 43 and 3), and occipital (BA 19) lobes and near BA 39 for white
matter (WM). These results underscore the distributed neural basis of
intelligence and suggest a developmental course for volume– IQ
relationships in adulthood.

However, in the very same issue, this article was also published raising questions about the validity of the way this technology is being used. This article, though, focuses primarily on flaws in group comparisons, not regression analyses, though does talk a bit about sample sizes. I'm not familiar enough with this technology to know if these same concerns would also relate to Haier's use of voxel-based morphometry, but it's always good to keep in mind potential caveats to any scientific study, especially ones utilizing new methods and applications.

NeuroImage 2004, 23: 17-20
Why voxel-based morphometric analysis should be used with great caution when characterizing group differences
C Davatzikos

A variety of voxel-based morphometric analysis methods have been
adopted by the neuroimaging community in the recent years. In this
commentary we describe why voxel-based statistics, which are
commonly used to construct statistical parametric maps, are very
limited in characterizing morphological differences between groups,
and why the effectiveness of voxel-based statistics is significantly biased
toward group differences that are highly localized in space and of
linear nature, whereas it is significantly reduced in cases with group
differences of similar or even higher magnitude, when these differences
are spatially complex and subtle. The complex and often subtle and
nonlinear ways in which various factors, such as age, sex, genotype and
disease, can affect brain morphology, suggest that alternative, unbiased
methods based on statistical learning theory might be able to better
quantify brain changes that are due to a variety of factors, especially
when relationships between brain networks, rather than individual
structures, and disease are examined.

[Moonbear]

But other physiological conditions have not been completely ruled out. Birth weight for example. Low birth weight is correlated with lower IQ scores in later life, and US blacks have systematically lower birth weights than whites. This gap persists into the more middle class communities too, so it isn't just a diet thing. Of course birth weight could have a large genetic component too, but it is at least ameliorable.

Age of the mother factors into this as well. Lower birth weights are associated with teen pregnancies, and teen mothers also are not likely to get adequate prenatal care.

Am J Prev Med. 2003 Oct;25(3):255-8.**
Correlates of unplanned and unwanted pregnancy among African-American female teens.
Crosby RA, DiClemente RJ, Wingood GM, Rose E, Lang D.

BACKGROUND: Evidence suggests that unplanned/unwanted pregnancy may be an important antecedent of negative birth outcomes, such as low birth weight. This study identified correlates of perceiving a current pregnancy as both unplanned and unwanted among unmarried African-American adolescents aged 14-20 years. METHODS: One hundred seventy pregnant adolescents were recruited during their first prenatal visit. Adolescents completed a face-to-face interview administered in private examination rooms. Adolescents also completed an in-depth self-administered survey. Measures were selected based on two potential influences: (1) relationships with boyfriends and (2) parent/family involvement. Age and parity were also assessed. Contingency table analyses were used to identify significant bivariate associations. Correlates achieving bivariate significance were entered into a forward stepwise logistic regression model. RESULTS: Pregnancy was reported as unplanned and unwanted by 51.2% of the study population. In a multivariate analysis, adolescents indicating lower levels of parental involvement were about twice as likely (adjusted odds ratio [AOR]=2.05; 95% confidence interval [CI], 1.1-3.9, p<0.03) to report that their pregnancy was unplanned and unwanted. Adolescents who already had a child (AOR=2.3; 95% CI, 1.3-5.7, p<0.009) and those younger than 18 years old (AOR=2.3; 95% CI, 1.1-4.5, p<0.02) were more than twice as likely to report that their pregnancy was unplanned and unwanted. A variable assessing whether each adolescent's current boyfriend conceived the pregnancy approached significance (AOR=2.33; 95% CI, 0.99-5.46, p=0.052). CONCLUSIONS: Findings provide initial evidence for specifically targeting intensified prenatal care programs to teens perceiving their pregnancy as unplanned and unwanted.


From introduction of above cited:
African-American adolescents were studied because the birth rate among African-American adolescent females (aged 15–19 years) is higher than that among all other ethnic/racial groups of U.S. females of the same age (85.3 per 1000 v 51.1 per 1000).[*8 ]

Their source for these statistics is:
Ventura SJ, Mathews TJ, Curtain SC. Declines in teenage birth rates, 1991–1998: update of national and state trends. Hyattsville MD: National Center for Health Statistics, 1999 [National Vital Statistics Report 47(26)]

[Evo]

I assume you are familiar with her significant contributions to the literature of psychometrics. I discussed the academic requirements that I believe are appropriate for a psychometrician in a recent message here.No, according to you, sociologists know nothing about psychometrics. Go back and read your own posts. It doesn't matter what their areas of expertise are, according to you.

We have people who are outstanding psychometircians who hold degrees in various fields.Not according to you, go back and read your own posts!

Amazing how if you agree with them, they meet "your" conditions and if you don't agree with them, they don't.

[Nereid]

Suppose I want to know my _g_ and how it may vary. I understand that I can take a test (e.g. an IQ test with high _g_ loading), some chronometric tests, or an EEG. From just one test – of any of these three kinds – what +/- number would my _g_ come with? What is the distribution (e.g. Gaussian)? How does each type of test vary wrt this +/-?Since most observers do not have the laboratory devices and skills to measure intelligence via chronometric or electroencephalography techniques, the most common approach is to use an IQ test. As you probably know there are very many IQ tests, although only a few of them are used in most serious research. Of these the Raven's is most often cited in research programs. The WAIS versions are also widely used. For most tests, _g_ has to be extracted by weighting the subtest scores according to their _g_ loadings. Obviously, different tests will have different _g_ loadings, different subtest structures, and different associated errors. As with measuring physical phenomena (consider temperature) there are errors that can be identified in connection with many aspects of the measurement. Most of these errors are small. Ultimately the reliability coefficient is of central importance. Jensen: "The difference between the reliability coefficient and unity represents the proportion of the total variance of the measurements that is attributed to measurement error. ... In my laboratory we have been able to measure such variables as memory span, flicker-fusion frequency (a sensory threshold), and reaction time with reliability coefficients greater than .99. ... The reliability coefficients for multi-item tests of more complex mental processes, such as measured by typical IQ tests, are generally about .90 to .95. This is higher than the reliability of people's height and weight measured in a doctor's office! The reliability coefficients of blood pressure measurements, blood cholesterol level, and diagnosis based on chest X-rays are typically around .50." [The _g_ Factor, P. 50]Thanks Mandrake.

However, I am still somewhat in the dark about _g_ and the individual; specifically, the +/- which psychometricians (in the field as well as in well appointed labs) assign to the results from just one test, of each kind (IQ, chronometric, EEG). Your comparisons with some tests done in doctors' offices is quite apt - and I'd like to explore this some more.

For now, I merely note that Jensen mentions 'measurement error'; my question certainly includes that, but is considerably broader.The concept of TRUE SCORE is related.
Regressed true score = [(reliability coefficient) x (test score - mean score for population)] + (mean score for population)
This is obviously a hypothetical score that attempts to factor out measurement error. For a very detailed discussion of all things related to measurement error, see Jensen, A.R. (1980). Bias in mental testing. New York: Free Press. Jensen says that tests with reliability coefficients of less than .90 should (generally) not be used.You're here talking about estimates of some kind of population mean (or other group statistic); I intend to get to this, but want to start with a good understanding of _g_ and the individual. Since _g_ has to do with my brain, and I know all kinds of things affect the performance of ‘brain tasks’, I’m sure psychometricians have done extensive research into the effects of the following on one’s _g_, as estimated by one of the three kinds of _g_ tests:
- alertness, e.g. taking the test mid-morning after a good night’s sleep vs one taken at 2am
- drugs, e.g. caffeine, alcohol, anti-histimines; especially those which are known to affect reaction times and medications for mental conditions
- pain, esp headaches
- general wellness/fitness, e.g. fever, top physical form, hunger,
- brain affecting illnesses or conditions, e.g. epilepsy, depression, Alzheimers, tumour, physical injury, PTSS
- mood
- age

How do estimates of _g_ vary for each of these classes of factors?I don't have a source at hand with a ready answer. When an IQ test is given, it is the responsibility of the test administrator to determine that the person taking the test is fully alert and not encumbered by factors that would render the test inaccurate. Some tests, such as the WAIS are age adjusted.In doing good science, of course we expect that the administration of tests be done so as to eliminate or control for extraneous factors which may influence the effects we seek to collect data on. My question here is only with research results on the measured size and nature of each of the above effects (and any others which psychometricians have discovered) on an estimate of _g_, for each class of test (IQ, e.g. WAIS; chronometrics, EEG); preferably expressed as a range that could be expected in the result of just a single test.

[Mandrake]

No, according to you, sociologists know nothing about psychometrics. Go back and read your own posts. It doesn't matter what their areas of expertise are, according to you.
Please quote me instead of commenting incorrectly. I was critical of the sociologist you referenced because she has not conducted psychometric research and she has not published in psychometric journals. She is not a participant in the peer review of psychometric papers. If you examine the list of publications you presented you will see that she is interested in other subjects.

Not according to you, go back and read your own posts!

I suggest that you read them before making such comments. On 8-25-2004 I wrote:

There is no requirement that a psychometrician hold a particular university degree. This is especially so because the field of psychometrics is quite removed from much of psychology and makes particularly heavy demands on statistical knowledge and laboratory research. The thing that distinguishes a psychometrician (or other specialist) is his devotion to the subject at hand, years of study, years of research, and participation in the publication of peer reviewed research. The women you listed are not qualified to peer review psychometric research.

[Nereid]

Nereid:

There are various papers that have examined the conditions of test taking. The range of things considered includes, for example, stress. Jensen used pulse rate to measure stress, but found that it did not significantly affect scores. A placebo effect would imply that something causes the person taking the test to score artifically high. I am unaware of any such finding. There are also various reports that such things as stimulants or even music can temporarily boost test scores. Presumably these findings indicate an induced error in the positive direction, since no findings have reported permanent improvements in intelligence due to such factors.Thanks.

Perhaps I haven't been clear enough; the effects of test conditions, pre-test expectations, etc on estimates of _g_ wouldn't necessarily be to boost an estimate, they could depress it (e.g. the 'white coat effect' makes some people appear less healthy than they 'really' are).

The music and stress factors look interesting; how much research has been done on such factors when tests are done in the field (vs in well appointed labs)? How large was the 'music' effect?

Assuming that psychometrics does cover things such as personality, aptitudes, and interests, and that psychometricians active in these fields have been as successful as Jensen appears to have been in intelligence, to what extent have _g_ psychometricians employed well constructed personality, aptitudes, and interests tests in conjunction with their _g_ tests?

[Nereid]

My suggestion is a LOT of reading of top quality text books and peer reviewed papers.

For a start, sentences in English with comparatives ('most', 'higher') don't help IMHO; the reality of population groups is very rich, and teasing apart the influences of multiple factors calls for hard thought.

In a discussion forum, such as this one, people can and do provide quotes and links, but cannot reasonably be expected to produce the necessary volume of information that would be required to detail research procedures, error analysis, multiple confirmations, etc. Unfortunately there are people who jump to the conclusion that all of the research that has been done was either done with malice (to discredit stupid people) or with incompetence. Neither is true. In the case of SES comparisons, there have been a lot of studies reported by very capable scientists. The details of their comparisons are not secret. Virtually all comparisons are made with an attempt to remove as many variables as possible. For example, you will find that in The Bell Curve many of the W-B comparisons are done for cohorts with identical IQs. If you examine the past few issues of Intelligence you will find data comparing job status by IQ deciles (I previously quoted it and do not wish to look it up again, but it favors blacks). In the US blacks above the 40th percentile earn more than whites of equal IQ.

In the case of SES, the issue is complex primarily because IQ causes SES and not vice versa. This point may not be a happy finding for some people, but it is well documented in The _g_ Factor. A discussion of SES as it pertains to IQ may also be found in The Bell Curve, starting on page 286.

The issue of malnutrition is obviously a canard in the US. The IQ gap exists for all SES groups and we all know that we do not have a nation of malnourished blacks and properly nourished whites. The cause if the intelligence gap is largely genetic. The entire environmental contribution to IQ is in the range of 20-30%, but that is an overstatement that assumes no error. The strong evidence of IQ and more importantly of _g_ heritability continues to pile up even more now that we have brain imaging. We can actually see the huge overlap between identical twin brains and the sharp reduction when brains of DZ twins are imaged. We have path analysis and MZA studies, both of which show nearly identical values in the 70-75% range. We have detailed inbreeding depression studies that are based on heritability, with measurements matching predictions. We have adoption studies showing virtually no family influence, no correlation between adoptees and their adoptive siblings, and all of these kids turn out to have IQs in the range of their not-adopted peers and in the range predicted by knowing the IQs of the biological parents. We have nutrition studies, showing that even famine does not affect the IQs of children born to malnourished mothers. This is not Ethiopia.


So, just look at the IQ measurements of Asians who were born in Asia and who still live there. I don't see your point. That data is not missing. I previously commented that Asians in Asia test the same as Asians in the US. Asians adopted in the US and Europe turn out to have IQs higher (this is all statistical, as I hope you know) that their adoptive families.


Rushton is a serious and respected scientist. He has published extensively in scientific journals and has conducted research internationally. He is a member of ISIR. Here is a list of his publications:
http://www.ssc.uwo.ca/psychology/faculty/rushton_pubs.htmI want to return to this, but only after I've understood much of the basics better first.

[Nereid]

Does Jensen go on to say what those 'plausible reasons' are? Subsequent to when Jensen wrote this, what research has been done to establish what that distribution actually is? Why did Jensen add the caveat "within the range of ±2σ from the mean"?This subject is discussed in much more detail in Bias in Mental Testing, Chapter 4. For example, Jensen wrote: "The simple fact is that a test unavoidably yields a near normal distribution when it is made up of (1) a large number of items, (2) a wide range of item difficulties, (3) no marked gaps in item difficulties, (4) a variety of content or forms, and (5) items that have a significant correlation with the sum of all other item scores, so as to ensure that each item in the test measures whatever the test as a whole measures." He goes on to point out that it would take a lot of effort to produce a test that is so screwed up that it would not produce a distribution that "departs at all radically from the normal."THis fact is behind the expectation of geneticists that the genetic component of g is produced by many genes. If there were just one, or a few, the different phenotypes would line up in discrete bunches, rather than a continuous distribution such as is found with sufficiently large populations.This doesn't come as any surprise; unfortunately, it surely makes doing good science in this field very difficult. For example, non-gaussianity is usually a clear sign that there is at least one systematic effect in play, but the converse is most definitely not true (I'm sure we can all give boatloads of examples where researchers fell into the trap of - unconsciously? - equating gaussianity with absence of confounding systematic effects). Further, if tests invariably yield gaussian distributions, hypotheses which predict non-gaussian ones will have a very hard time getting their 'day in court'.

Any answer to the "within the range of ±2σ from the mean" question? Edit: never mind; hitssquad's post (Jensen quote) addresses this nicely.

[Nereid]

Probably the best answer at present concerning the distribution of g is that, although we cannot determine it directly by any currently available means, it is a reasonable inference that it approximates the normal curve and there is no good reason for assuming that the distribution of g is not approximately normal, at least within the middle range of about four standard deviations. Most psychometricians implicitly work on the statistically advantageous assumption of normality, and no argument has yet come forth that it is theoretically implausible or adversely affects any practical uses of g-loaded tests. But the question is mainly of scientific interest, and a really satisfactory answer to it cannot come about through improved measurement techniques per se, but will become possible only as part and parcel of a comprehensive theory of the nature of g. If we have some theoretical conception of what the form of the distribution should be in a population with certain specified characteristics, we can use random samples from such a population to validate the scale we have devised to measure g. The distribution of obtained measurements should conform to the characteristics of the distribution dictated by theoretical considerations.[/list](Arthur Jensen. The g Factor (http://www.questia.com/PM.qst?a=o&d=24373907). pp101-103.)Thanks hitssquad; the whole quote is very illuminating, but I found this last para to be of particular value; we'll surely be returning to it.

[Nereid]

Age of the mother factors into this as well. Lower birth weights are associated with teen pregnancies, and teen mothers also are not likely to get adequate prenatal care.Some time ago I think I read that a long-standing problem in US education had moved a giant step forward towards resolution - falling average SAT scores (or something like that). IIRC, the resolution was birth order and/or birth spacing - first-borns do differently (better?) on SATs than second-borns, who in turn ... Apparently the childhood environment wrt siblings has a considerable effect.

Can someone tell me if my poor old memory is even approximately right?

As SAT scores correlate well with _g_ (or, as I'm beginning to learn to say, "SAT tests have a high _g_ loading"), does it follow that one's _g_ is partly determined by one's birth order and/or age difference of one's siblings? What have US intelligence psychometricians found here? What have non-intelligence US psychometricians found (e.g. wrt personality, aptitudes, interests)?

[Evo]

Please quote me instead of commenting incorrectly. I was critical of the sociologist you referenced because she has not conducted psychometric research and she has not published in psychometric journals. She is not a participant in the peer review of psychometric papers. If you examine the list of publications you presented you will see that she is interested in other subjects.Why would she have to be a psychometrician when she was arguing genetics? She's an expert in genetics, which is what she was discussing. Neither Hernstein or Murray are geneticists, which is why they are not qualified to make the assumoptions they did about genetics.

I suggest that you read them before making such comments. On 8-25-2004 I wrote:

There is no requirement that a psychometrician hold a particular university degree. This is especially so because the field of psychometrics is quite removed from much of psychology and makes particularly heavy demands on statistical knowledge and laboratory research. The thing that distinguishes a psychometrician (or other specialist) is his devotion to the subject at hand, years of study, years of research, and participation in the publication of peer reviewed research. The women you listed are not qualified to peer review psychometric research.Which is exactly why your argument made no sense, they were both experts in genetics, which is what they were discussing. According to you, a person cannot be qualified in anything but their degree.

[Nereid]

Thanks hitssquad.Reaction time is composed of decision time and motor time. Caffeine may affect motor time, but AFAIK it has not been shown to affect decision time. Other drugs such as Bacopa Monniera (AKA the ayervedic herb Brahmi) may affect decision time, as Bacopa itself has been shown (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=11498727) to affect the related variable inspection time and has been shown to increase g (as measured by standard psychometric batteries in a controlled study).There are huge 'problems' in sports wrt 'performance-enhancing' drugs. I would expect that for some sports (e.g. fencing, pingpong; motorcar racing?), a drug which could improve either decision time or motor time (or both!) would be of considerable interest. At the least I would expect that the drug testers in sports would have a list of drugs known to improve RT; when I get time I'll do some googling.

What other detailed studies have been done into the effects of drugs on measured _g_?

IIRC, some elite athletes get an 'unfair' advantage over their competitors because they have rare genetic mutations, e.g. very high production of red blood cells; I also remember reading that elite fencers are 'lefties', because lefties have inherently faster RT. What is known about the incidence of genetic mutations which markedly affect RT (in either direction)?g is known to smoothly drop in adults with age, as I have mentioned many times on Physics Forums and which I mentioned many times as a raison d'être for anti-senescence efforts.

This page has a nice graph of what is likely happening to you as you read this:
http://hiqnews.megafoundation.org/Definition_of_IQ.html

Age-related cognitive decline is also being discussed (http://www.childrenofmillennium.org/phpBB2/viewtopic.php?t=50) over at the Children of Millennium forums:


As you age beyond the age of 18, your physical brain-decay (glycoxidation; amyloid beta build-up; mitochondrial damage; DNA damage) can be clearly watched in slow motion in the form of your raw scores predictably dropping point by point, year by year.

IQ scores on IQ tests correct for this post-18 brain rot, and you are given a same-age-peers curve-graded IQ score (in addition to being allowed to cheat with a massively-larger vocabulary than your g would otherwise imply -- boosted vocabulary subtest scores via vocab cheating by oldsters on the Weschler averages +.80 S.D. {and that's not counting the other free full-scale IQ points they get because their peers have physical brain rot}, according to a brand new study {see at the bottom of this post Verhaeghen; see also MacLullich, et al}).Do all adults age at the same rate (wrt _g_)? What does research show wrt variations in the decline of _g_ with age, e.g. men vs women, menopause, those who use their intelligence vs those who don't, the 'old oldies' (those who remain in good physical and mental health well into their 70s, 80s, and 90s) vs everyone else?

[Nereid]

{extract; my emphasis}
Spearman's g is this number for the first principal component of just about every IQ test and surrogate ever invented. It is enormously stable and correlated with things like the SAT, the Armed Forces tests, and so on. It also has physical correlates like measured reaction time and volume of gray matter in the prefrontal cortex.I came across a recent study that looks at intelligence and specific areas or patches of gray matter. They did not do a correlation as such, but it does look like they are locating those areas related to g, as well as other factors like fatty tissue around axons, glucose uptake, etc. But at least the IQ vs. Brain size is getting narrowed down to IQ and specific brain reqions." While gray matter amounts are vital to intelligence levels, the researchers were surprised to find that only about 6 percent of all the gray matter in the brain appears related to IQ." {From Human Intelligence Determined By Volume And Location Of Gray Matter Tissue In Brain Source: University Of California - Irvine Date: 2004-07-20}

[...]

Some brain and head size related factoids:

The average female brain is smaller than the average male brain. This is true, even after the size difference is corrected for relative differences in body size. The average male brain is about 12.5% heavier.

The average female brain has more neurons per unit volume than the average male brain (about 11%).

The average brain and head size is smaller for blacks than for whites.

The number of neurons in the brain is fixed by age 4, but the brain size to intelligence correlation is weak at age 4. By age 7 there is a significant within family effect. Miller argues that this is consistent with his myelination hypothesis because myelination of the brain is not significant at age 4, but is much more so at 7 and continues through adolescence.

The correlation between body size and brain size in adults is between .20 and .25.

The correlation between head size and IQ ranges from .10 to .25 (various studies), with a mean of .15.

The correlation (one study only) between head size and _g_ is .30.

The correlation between brain size, as measured by MRI, and IQ is .40 (corrected for body size).Moonbear has two highly relevant posts too, they are too large to copy here, so
link1 (http://www.physicsforums.com/showpost.php?p=294356&postcount=40), link2 (http://www.physicsforums.com/showpost.php?p=296181&postcount=76) ." The relation between brain size and intelligence has been shown by dozens of studies, including state-of-the-art magnetic resonance imaging. Orientals average 1 cubic inch more brain matter than Whites, and Whites average a very large 5 cubic inches more than Blacks. Since one cubic inch of brain matter contains millions of brain cells and hundreds of millions of nerve connections, brain size differences help to explain why the races differ in IQ." {from Is There a Biological Basis for Race and Racial Differences? By J. Philippe Rushton Insight, May 28, 2001}It would seem that this topic isn't quite as clear-cut as SelfAdjoint's post would imply. For example, it seems that Rushton's work has been seriously questioned, and that he himself has found much smaller differences in his later work than he reported originally (an example (http://www.mugu.com/cgi-bin/Upstream/People/Rushton/rushton-peters.html)).

The research quoted by both Moonbear and Mandrake seem to show that 'intelligence' isn't particularly well localised in the brain. Further, the sex differences would seem to suggest that brain volume, in whole or in part, should not correlate with intelligence.

But let's assume that they do. Then we find some really interesting results, for example:
- the variation in brain volume within a population group is far larger than that between population groups (so, naively, you would expect there to be little IQ difference between population group averages)
- just as skin colour is an adaptation to UV, so aspects of head size and shape are adaptations to local climates - e.g. arctic vs tropical (so, naively, you might expect that any IQ differences would correlate with climate adaptation, if only weakly)
- the prefrontal cortex comprises ~12.5% of human brains, and ~10.6% of baboon brains (source (http://content.karger.com/ProdukteDB/produkte.asp?Doi=6620)). If the brain volume variations claimed by Rushton are due purely to IQ, which is found only in the prefrontal cortex, then variations in human prefrontal cortex volume (as a % of total brain volume) should be far in excess of the difference between the average human and the average baboon (5 cubic inches (~82 cm3) is approx 6% of the total human brain volume) - so, naively you would expect that brain volume should have nothing to do with IQ (the regions which are responsible for intelligence are far too small - as a % of the total brain - for anything but huge variations in these to be responsible for the observed brain volume differences among humans).

[Mandrake]

It seems that there may be more than one 'APA report'; could someone please tell me whether this (http://www.apa.org/releases/intell.html) is the one we're discussing?

The material you quoted was a press release. The comments I made were directed at the following:
Report of a Task Force established by the Board of Scientific Affairs of the American Psychological Association
Released August 7, 1995
A slighted edited version was published in the American Psychologist, Feb 1996.

[Waterdog]

The newspaper was the Wall Street Journal, Tuesday, December 13, 1994. The letter it printed was written by Linda Gottfredson, although it was not attributed to her. It was signed by, as I recall, 52 scholars.


Close. I just counted six. Detterman reported (in Intelligence) the details of how, why, and under what conditions that letter was written. There are very good reasons behind its final form and the people who signed it.



This was the advert in which Jensen, Rushton, and Lynn all acknowledged that the IQ gap between blacks and whites in the US was more likely the result of environmental influences than genetics. Quote:

"There is no definitive answer to why IQ bell curves differ acrossracial-ethnic groups. The reasons for these IQ differences between groups may be markedly different from the reasons for why individuals differ among themselves within any particular group (whites or blacks orAsians). In fact, it is wrong to assume, as many do, that the reason whysome individuals in a population have high IQs but others have low IQs must be the same reason why some populations contain more such high (or low) IQ individuals than others. Most experts believe that environment is important in pushing the bell curves apart, but that genetics could be involved too."

<http://www.lrainc.com/swtaboo/taboos/wsj_main.html>

That is the statement that Lynn, Rushton and Jensen all signed: "Most experts believe that environment is important in pushing the bell curves apart, but that genetics could be involved too." Genetics could be involved too. It is hilarious that most of the race-and-IQ enthusiasts seem not even to have read all of the documents that they cite in support of their position. If it has really been scientifically proven that IQ is mostly a result of genetics, as the highly vocal crowd of internet-message-board enthusiasts never tires of claiming, then why did all of those scientists sign a public statement to the contrary? Note that this statement also warns against procedures such as applying the results of twin studies conducted within a country to international IQ differences, another favorite ploy of the ever-inventive race-and-IQ crowd.

[Mandrake]

However, I am still somewhat in the dark about _g_ and the individual; specifically, the +/- which psychometricians (in the field as well as in well appointed labs) assign to the results from just one test, of each kind (IQ, chronometric, EEG). Your comparisons with some tests done in doctors' offices is quite apt - and I'd like to explore this some more.

As I attempted to explain before, the errors associated with any measurement are a function of the measurement tool. It is also possible to combine measurements when their variances add. This is done with individual test items and is done with individual elementary cognitive tests. One would expect that a more heavily _g_ loaded test would produce a more robust measurement than a less _g_ loaded one. The only way to get at the numbers you wish to find is to find them in the literature. The most through discussion of psychometric measurement tools that I have seen is Jensen's Bias in Mental Testing. There is some information in The _g_ Factor. There is, as I previously noted, a great deal of related information in most serious research papers that are based on measurements.

In doing good science, of course we expect that the administration of tests be done so as to eliminate or control for extraneous factors which may influence the effects we seek to collect data on. My question here is only with research results on the measured size and nature of each of the above effects (and any others which psychometricians have discovered) on an estimate of _g_, for each class of test (IQ, e.g. WAIS; chronometrics, EEG); preferably expressed as a range that could be expected in the result of just a single test.
You will have to dig it out of the literature, unless hitsquad happens to have some numbers handy. IQ tests typically correlate with _g_ at around .9 or so. In the case of the Raven's Jensen has commented that it is essentially a pure measurement of _g_, but naturally contains some loading on _e_. IQ test results are sometimes stated with an assigned range. You get the numerical value and a plus or minus range that corresponds to a stated confidence level. As you know, most statistically determined measures are stated in terms of probability and confidence level.

[Nereid]

The material you quoted was a press release. The comments I made were directed at the following:
Report of a Task Force established by the Board of Scientific Affairs of the American Psychological Association
Released August 7, 1995
A slighted edited version was published in the American Psychologist, Feb 1996. Whew! Glad we cleared that up! :smile: Thanks Mandrake.

[Mandrake]

Perhaps I haven't been clear enough; the effects of test conditions, pre-test expectations, etc on estimates of _g_ wouldn't necessarily be to boost an estimate, they could depress it (e.g. the 'white coat effect' makes some people appear less healthy than they 'really' are).
All of the information I have seen indicates that, if the person is rested, healthy, etc. the test scores are not going to be significantly boosted or depressed by the testing environment. One obvious condition for testing is quite and freedom from outside distractions. We sometimes hear people commenting that an individual doesn't test well. In such situations, the most likely reason the person doesn't test well is that he is not as intelligent as he would like to believe.

The music and stress factors look interesting; how much research has been done on such factors when tests are done in the field (vs in well appointed labs)? How large was the 'music' effect?
There is information available on the effects of various factors, such as stress. As I recall the material from Jensen is in his textbooks. The effect of music first appeared in Nature in 1993 and was then called the Mozart Effect. It was touted by the press. Various reviewers contended that the claims were not valid. The issue did not go away. There have been additional reports, such as The Mozart Effect, From New Scientist, 6 November 1999. "For the sake of consistency, almost all studies on the Mozart Effect so far have focused on a single piece of music, the Sonata for Two Pianos in D Major (K 448), though some have measured the effect from other music as well. "It is not just this composition, and not just Mozart," says Rauscher. However, the researchers don't know why the Sonata in D works or which other pieces might."

[Mandrake]

As SAT scores correlate well with _g_ (or, as I'm beginning to learn to say, "SAT tests have a high _g_ loading"), does it follow that one's _g_ is partly determined by one's birth order and/or age difference of one's siblings?
Intelligence appears to have at least some negative correlation with parity.

What have US intelligence psychometricians found here?
Would you expect psychometricians from New Zealand, England, Canada, and Germany to arrive at different findings?

What have non-intelligence US psychometricians found (e.g. wrt personality, aptitudes, interests)?
Who are these people? Can you name a few of the better known ones?

[Mandrake]

Do all adults age at the same rate (wrt _g_)?
Quick answer: "no."
Intelligence declines at different rates, causing a significant divergence among people who were once peers. Also, intellectual strengths decline at different rates. Some begin to decline early in life, while others (such as verbal abilities) increase until relatively late in life. You seldom find old people making the kinds of scientific discoveries that earn Nobel Prizes in physics. The value of h^2 increases throughout most of life. If you look at Catell's theory, you will see differences in fluid and crystallized intelligence measures. These are basically second order factors (from factor analysis).

The expert in the study of the study of the psychology of Aging is Timothy Salthouse. He has published several papers in Intelligence that deal with age-related variance. The most general finding is the obvious one that people slow down as they age, thereby making direct comparisons of various studies impractical, when the test subjects are not selected from the same age group. The decline in RT/IT measurements has been independently verified to be substantially caused by a slowing of cognitive processing (as opposed to sensory factors). “Salthouse predicted that the correlation between age and IQ should virtually disappear if mental speed was partialled out. … the correlation between age and RAPM was - .28. After partialling out latency, the correlation between age and RAPM was reduced to a not statistically significant -. 10. Again, this generally supports Salthouse’s contention that a decrease in mental speed is responsible for all age-related declines in fluid intelligence.”
* DOUGLAS A. BORS and BERT FORRIN, Age, Speed of Information Processing, Recall, and Fluid Intelligence, Intelligence 20, 229-248 (1995).

[nuenke]

Gottfredson is a sociologist (http://www.google.com/search?q=linda+gottfredson+sociologist).

She is a sociologist who specializes in general intelligence, with regards to intelligence being correlated with school and job performance. That is her area of expertise. Not everyone doing research in intelligence is a psychometrician - there are many areas of specialization. But she is one of the major contributors to the journal INTELLIGENCE and a major contributor to the science of mental ability. The fact that she does this as part of sociology rather than psychology is not germane. The point is, is she active in the field, and is her work supported and complemented by psychometricians. The answer is clearly yes.

On the other hand look at people like Gardner and Sternberg. They continue to be on the fringes trying to draw a line in the sand with regards to the importance of g and its implications for the workforce as well as racial differences. What determines any persons expertise is a history of solid, respected, verifiable research. There is no one litmus test. It is a matter of convincing others in the field that your hypotheses is better than some other hypotheses. As far as I know, no other hypotheses other than Jensenism has withstood the test of time and scientific grounding. The others are all fringe, non-falsifiable, just-so stories.

[hitssquad]

Thanks hitssquad.There are huge 'problems' in sports wrt 'performance-enhancing' drugs.There are no elite competitive athletes that I am aware of who do not use performance-enhancing drugs. Most performance-enhancing drugs are not barred by sports bodies.



I would expect that for some sports (e.g. fencing, pingpong; motorcar racing?), a drug which could improve either decision time or motor time (or both!) would be of considerable interest.Caffeine is such a drug (motor time enhancing and also peak explosive strength enhancing and athletic endurance enhancing), and it is interesting enough that virtually all athletes use it to enhance performance.



At the least I would expect that the drug testers in sports would have a list of drugs known to improve RTOn its face, that would seem to be a strange expectation.



when I get time I'll do some googling.Try PubMed (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed&term=athletic+caffeine).



What other detailed studies have been done into the effects of drugs on measured _g_?Try PubMed (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed&term=nootropic+working+memory). I listed (http://groups.yahoo.com/group/e-l/message/8388) a few over at e-l last year. Here (http://groups.yahoo.com/group/e-l/message/8383) is a related e-l message.



What is known about the incidence of genetic mutations which markedly affect RT (in either direction)?I would not know.



Do all adults age at the same rate (wrt _g_)?No. g tends to decline commensurately with decline of physical parameters. Some people age more slowly than others. This seems to be largely mediated by their body's relative production levels of antioxidants such as SOD and uric acid.

People can radically increase their rates of mental decline by abusing alcohol and other drugs and exposing themselves to biologically damaging levels of various chemicals. Lack of micronutrient intake, relative to that of same-age peers, will also increase rate of mental decline, as will lack of food-based antioxident (flavonoids, polyphenolics) intake, again relative to that of same-age peers.

Some adults have managed to virtually halt, relative to that of same-age peers, both their mental and physical age-related decline. These persons have adopted comprehensive anti-senescence regimens. Many of these persons refer to themselves as life extensionists (http://groups.google.com/groups?group=sci.life-extension).

Persons with lower IQs to begin with tend to be relatively incompetent at preserving their own health. Thus, the present author would expect that persons with lower IQs to begin with would also suffer greater age-related declines in IQ relative to those of same-age peers. See the recent paper (http://www.google.com/search?q=Gottfredson+health+iq) by Gottfredson on IQ and relative hygiene competency.



What does research show wrt variations in the decline of _g_ with age, e.g. men vs women,Females are known to age more slowly than men, physically. Based on that, I would expect that female cognitive decline is generally also retarded.



menopause,Age-related hormone decline is known to dramatically affect cognitive parameters. Hormone replacement therapy is known to have an opposite dramatic effect (http://www.lef.org/protocols/prtcl-003.shtml) on cognitive recovery in older persons. This effect is mainly attributed to myelination, which is known to be largely mediated by the so-called "sex hormones".



those who use their intelligence vs those who don'tPersons with higher IQs in the first place are known to "use their intelligence" more. This would seem to have to be controlled for, and I do not know if any studies have yet been designed to do that.



the 'old oldies' (those who remain in good physical and mental health well into their 70s, 80s, and 90s) vs everyone else?There has never been a single documented case of any human reaching the age of 70 in good cognitive health. Before the recent life extension revolution, cognitive decimation on the order of several standard deviations was the norm for 70-year-olds. Persons who are relatively, compared with same-age peers, physically and mentally healthy in their senior years are relatively, compared with same-age peers, physically and mentally healthy in their senior years. Maybe you wanted to know if they were also relatively healthier than average when they were younger. Answer: generally, they were.

[Mandrake]

Some adults have managed to virtually halt, relative to that of same-age peers, both their mental and physical age-related decline. These persons have adopted comprehensive anti-senescence regimens.

This is recent and related:
http://www.sciencedaily.com/print.php?url=/releases/2003/01/030128080418.htm

Study Is First To Confirm Link Between Exercise And Changes In Brain

CHAMPAIGN, Ill. -- Three key areas of the brain adversely affected by aging show the greatest benefit when a person stays physically fit. The proof, scientists say, is visible in the brain scans of 55 volunteers over age 55.

The Journal of Gerontology study involved well-educated men and women aged 55 to 79. Their fitness ranged from sedentary to very fit, competitive-ready athletes. Fitness was measured by results of one-mile-walking and treadmill stress tests. Three-dimensional scans of the participants' brains were done using MRI equipment at Carle Foundation Hospital in Urbana. Applying voxel-based morphometry, researchers estimated tissue atrophy in a point-by-point fashion in the targeted regions of the brain.

"Interestingly, we found that fitness per se didnÕt have any influence on brain density," said Kramer, a professor of psychology and member of the Beckman Institute for Advanced Science and Technology at Illinois. "It is fitness as it interacts with age that has the positive effects. Older adults show a real decline in brain density in white and gray areas, but fitness actually slows that decline."

The quoted material is just a sample. The article is interesting.

[Moonbear]

You seldom find old people making the kinds of scientific discoveries that earn Nobel Prizes in physics.

Sorry to pick nits here, but there are two obvious social reasons I can think of that can easily account for this other than mental decline. 1) Nobel prizes are usually for work that has really made new breakthroughs and advancements. It's hard to show this has happened soon after a discovery is made, but rather requires the test of time to show it holds up to further scrutiny and actually leads to the advances implied at the outset. So, older scientists just don't stay in the game long enough to get to that point if they only make such a great advancement late in career. 2) You don't find too many senior scientists at the bench. They are trapped in administrative roles, so their great ideas are usually passed on to their students to test.

[Tigers2B1]

Sorry to pick nits here, but there are two obvious social reasons I can think of that can easily account for this other than mental decline. 1) Nobel prizes are usually for work that has really made new breakthroughs and advancements. It's hard to show this has happened soon after a discovery is made, but rather requires the test of time to show it holds up to further scrutiny and actually leads to the advances implied at the outset. So, older scientists just don't stay in the game long enough to get to that point if they only make such a great advancement late in career. 2) You don't find too many senior scientists at the bench. They are trapped in administrative roles, so their great ideas are usually passed on to their students to test.

Your #1 doesn't make sense to me, even if true. #2, IF true, begs the question - why?

[Moonbear]

Your #1 doesn't make sense to me, even if true. #2, IF true, begs the question - why?

Not sure what about #1 doesn't make sense, so can't clarify.
Re: #2. It's just the way university culture works. Even if someone is a fantastic bench scientist, there are ever increasing pressures to take on administrative responsibility. It starts out small when you're early in your career...you have to serve on some committees to get tenure...then it increases from there...chair a committee, or two, take on the role of journal editor, then editor-in-chief (afterall, journals want those experts running the show), first you review grants, then you chair the study section...it's rather endless. Others are promoted to be graduate program directors or department chairs. It's a strange contradiction in the way universities run...the better you are at doing research, the more they seem to want to pull you away from it by giving you other administrative roles.

[Nereid]

Not sure what about #1 doesn't make sense, so can't clarify.
Re: #2. It's just the way university culture works. Even if someone is a fantastic bench scientist, there are ever increasing pressures to take on administrative responsibility. It starts out small when you're early in your career...you have to serve on some committees to get tenure...then it increases from there...chair a committee, or two, take on the role of journal editor, then editor-in-chief (afterall, journals want those experts running the show), first you review grants, then you chair the study section...it's rather endless. Others are promoted to be graduate program directors or department chairs. It's a strange contradiction in the way universities run...the better you are at doing research, the more they seem to want to pull you away from it by giving you other administrative roles.It sure would be very interesting to see a decent sociological study alone these lines! In the meantime, we can (I'm sure) all give anecodotes. One of my favourites is John Bahcall, who played an extraordinarily important role in neutrino research in the last ~40 years, esp in the astrophysical arena. His capabilities got him dragged into all manner of committees, panels, etc; an example of the latest being on what to do about the Hubble Space Telescope. Amazing as it might seem, he still seems to find time to do really first rate research (although I suspect he outlines the program to bright students, and just checks in whenever he can; the 'bench work' is done by others). An recent example: a superlative paper on observations on the variation in alpha (the fine structure constant) over cosmological time; his finding? no change, within the limits of the observations. Why superlative? Because he found a method to do a test which automatically eliminated so many of the 'other factors' which plagued other efforts before his study.

[Mandrake]

There seem to be a few (hopefully not more) participants here who either do not understand or do not believe the science that has shown the strong heritability of intelligence. I just read an interesting interview with the fameous psychometrician Raymond Cattelle. Here is a comment from the interview:

Interview With Raymond B. Cattell
Originally published in The Eugenics Bulletin, Spring-Summer 1984

Raymond B. Cattell obtained his Ph.D. and D.Sc. at London University, where he worked with Spearman developing the theory of intelligence measurement. He has since taught at Harvard and has been for 30 years Distinguished Research Professor at the University of Illinois. His research publications cover 80 books and over 400 articles. His latest book is The Inheritance of Personality and Ability, which has been hailed for its methodological breakthroughs.

How do you think the irrational opposition to the idea of genetic influences on human behavior cane into being, and why does it persist?

CATTELL: One might suppose that all one had to do to overcome this opposition was to point to striking research in behavior genetics. But this research has been around for some time, and still the opposition persists. For example, there are five successive studies of criminal behavior cited in my 1982 book. They show that if a man in prison has an identical twin, it's likely his cotwin will also be in prison. If the twin is fraternal [with 50 percent shared genes, on the average], the likelihood is not nearly as great that he'll be in prison, too, but it's greater than chance. How could one possibly account for this difference with environmentalist explanations? The strong genetic component in criminality has already been proven up to the hilt.

The role of genetics in personality and intelligence has been extensively demonstrated in the last 30 or 40 years. The information is available in numerous textbooks. In almost all traits an appreciable genetic influence exists, varying from 70-80 percent in the case of intelligence, to about 20 percent in the case of superego.

Now, the question is: why aren't these facts known to the American people? Why have academe and the media withheld this information? In Britain, when I was growing up in the '20's, it was common sense to place considerable importance upon heredity in choosing a person to marry, in choosing the occupation for which one was suited, and so on. I was astonished when I came to America to find that eugenics was almost a bad word. One may trace this situation to the sociologists, to Boas and others, and to pressure from minority groups who oppose anything aristocratic.

I think there is a problem widespread in certain societies, notably in America, which consists of the denial, for political or other reasons, of the influence of genetics on human behavior. Of course, the Declaration of Independence has written in it Jefferson's and Franklin's statement that "all men are created equal." Now, neither of those men could possibly have believed that literally, as their other writings amply attest. But to my amazement, I find that two out of three people I ask take that statement to mean that they're genetically equal. The ideal of equality of opportunity has been distorted to mean biological equality. Roger Williams has written a telling little book [Free and Unequal, by Roger J. Williams, 1953; Liberty Press, Indianapolis] about inequality and freedom. He points out that the French Revolutionary trio of ideals of "Liberty, Equality, Fraternity" is internally inconsistent--a society can't have both liberty and equality. Given that people are born unequal in their innate abilities, the only way for a government to bring about equality is by coercion, but ultimately it's futile.

There may also be deeper, unconscious sources of opposition to any form of biological determinism. For example, the individual may feel that heredity somehow restrains him, so he will prefer to deny its influence. But obviously the only reasonable way to deal with nature is to accommodate to its laws, as we do to the law of gravity. If one refuses to acknowledge the importance of gravity and blithely jumps off a cliff, one will find himself in serious trouble. Our society may be jumping off a cliff, so to speak, with regard to its denial of the role of genetics in human behavior.

[Mandrake]

The research quoted by both Moonbear and Mandrake seem to show that 'intelligence' isn't particularly well localised in the brain.
That seems to be the implication of the latest information. We are at the beginning, not the end, of the resolution of how and where the brain processes thoughts.

Further, the sex differences would seem to suggest that brain volume, in whole or in part, should not correlate with intelligence.
Lynn has convincingly demonstrated that the mean IQ for women is 4 points below the mean for men. This difference is entirely due to group factors and as such does not conflict with Jensen's frequently reported finding that there is no difference in the mean _g_ for men and women. The primary group factors at work are presumably spatial and quantitative.

- just as skin colour is an adaptation to UV, so aspects of head size and shape are adaptations to local climates - e.g. arctic vs tropical (so, naively, you might expect that any IQ differences would correlate with climate adaptation, if only weakly)
Evolutionary adaptations are going to be driven by advantages in the existing environment that contribute to increased probability that the holders of the genetic allele will survive to reproduce and that their children will do the same. If the existing climate does not contribute to that result, why would you expect an adaptation? Lynn has argued that it was extreme climate that caused increased spatial performance in Mongoloids (contributing to a slight IQ advantage relative to Caucasoids). He also speculated that this spatial advantage may have come at the price of decreased verbal abilities (both differences are measurable).

- the prefrontal cortex comprises ~12.5% of human brains, and ~10.6% of baboon brains. If the brain volume variations claimed by Rushton are due purely to IQ, which is found only in the prefrontal cortex, ...

At present, the evidence points to IQ contributions in various parts of the brain, not just the prefrontal cortex. There was a strong hint of this in earlier research. That research involved the destruction of 48 locations of rat brains (there were meticulous control groups, pairs, etc.), followed by measurements of _G_ (upper case is used to designate the general factor in animals). The total findings are quite revealing and are reported on page 165 of The _g_ Factor. I am uninclined to type the whole result. Part: "Probably the most important finding is the very high correlation between the various tasks' _G_ loading and the number of brain structures that are significantly involved in the task performance -- a rank-order correlation of _.91."

Heavily loaded task = 17 brain structures
Simple task + 4 brain structures

"The _G_ factor correlated -.45 with the presence of _any_ brain lesion."

Britt Anderson determined that the _G_ factor scores for rats correlates with brain weight (they killed the unfortunate rodents) at r= +.48.

The subject of brain size has drawn a great deal of research attention for a very long time. I searched the INTELLIGENCE database and found 21 hits on "brain size." Some of the papers are very interesting, but way to long to discuss as part of this post. Since anyone seriously interested in psychometrics will have (and will have read) a copy of The _g_ Factor, they can review Jensen's comments through the entire chapter titled "Causal Hypothesis." Jensen goes through the math on page 442 to show that measurement data suggest that about 6 points of the W-B IQ gap are due to differences in brain volume. In comparing Negroid, Caucasoid, and Mongoloid means, he says "The regression of median IQ on mean cranial capacity is almost perfectly linear, with a Pearson r= +.998." After giving reasons, he goes on to say "Thus it appears that the central tendency of IQ for different populations is quite accurately predicted by the central tendency of each population's cranial capacity."

The same chapter includes a through discussion of the male-female difference.

The cranial capacity vs. IQ effect is found both within families and between families (P. 441) Jensen says that this implies that the relationship is intrinsic.

[NoahAfrican]

I do not think that anyone here is denying the genetics in inherited and thus passes traits to offspring. Eugenics, or whatever, is not at issue here. The issue is in your failure to prove racial differences in testing is rooted in genetics.

Presenting very well educated individuals, who perform studies, is not PROOF of anything. It is simply a BELIEF in them. As I said, if a priest can molest a child, then surly a scientist can bring prejudice into his work. Scientist are not GODS, they are human and subject to emotions and biases.

As I stated before, if an individual has no means of verifying a supposed truth or fact, how does one then choose which ones to believe, from an always variable array of options? Also, how does one then prevent their own biases from determining which thesis is true?

Mandrak and his array of googled authors means nothing and proves nothing. I can tell you that I am 7 foot tall…how could you confirm or deny this? How can any of you prove or disprove it? How can any of you prove or disprove the studies? YOU CANT….all you can do is PICK what you want to believe…because you have know way of knowing and you choice will be biased toward supporting your preconceived notions.

Jensen said...., jensen said......jensen said.....jensen said.....jensen said.....

Is jenson the Son of God or maybe Jensen is God all mighty...the most high....

All hail Jensen....

WHere does Jensen live...I need to get my directions right so I can know which directions to pray...when I pay homage to his rightousness.

[iansmith]

They show that if a man in prison has an identical twin, it's likely his cotwin will also be in prison. If the twin is fraternal [with 50 percent shared genes, on the average], the likelihood is not nearly as great that he'll be in prison, too, but it's greater than chance. How could one possibly account for this difference with environmentalist explanations? The strong genetic component in criminality has already been proven up to the hilt.

The problem here is that the example does not prove that there is genetic link. The environment could be in question. Two twin brother in prison. Both grew in the same environment. Was the parents, other relatives in prison?

A better example would be the following.

In my familly, there seems to be high percentage of individual on paternal side with great intellectual capacity. First, 5/8 of my uncle/aunt had not problem learning at school and can do high intellectual work with few effort and 10/15 indiviuals of following generation and 2/3 of the third generation have the same abilities. This lead to suggest that a gene may be responsible for the this intellectual abilities but firts, you have to factor in the environment. The first generation grew up in a working class in the 1960's. This is not enviroment that promote great intecllectual and the proof stand in the fact that none of the first generation have bachelors degree as their first diploma. They all have technical or no college degree. Very few individuals of the second generation grew up in the same city but they are all from middle class. Already the socio-economic status has increase and 3 of the most gifted have Bachelors. Some of the most gifted have no college diploma, even after several attemps. The third generation lives have the same socio-economic status as their parents, however they are too young to be assess in terms of their academic stating but their learning curve is rapid.

Look at this, it suggest that the intellectual ability of this family is inherited. It can only be stated because three generation were assess for the socio-econmoic status and I look at the whole generation not only at a few individuals. To prove that the heridity exist, you have to compare the gifted against the average individuals at the genetic level. Heredity can only be proven if there is genes associated with it. Once you have what you think is responsible then you have to compare it with other families with suspected heretable gifts.

None of the research stated looked at the genetic level of the heredity. Therefore, most studies, at best, suggest that inheritance should be look at as a factor.

[hitssquad]

They show that if a man in prison has an identical twin, it's likely his cotwin will also be in prison. If the twin is fraternal [with 50 percent shared genes, on the average], the likelihood is not nearly as great that he'll be in prison, tooThe problem here is that the example does not prove that there is genetic link. The environment could be in question. Two twin brother in prison. Both grew in the same environment. Was the parents, other relativesIan, the fraternal twins are other relatives. Fraternal twins are both not as genetically related as identical twins, and — unless adopted away — raised in the same environment (except the microenvironment of the home; see Jensen 1998 regarding home microenvironments).


The macroenvironmental variables responsible for the transient between-families variance in g would therefore seem to be an unlikely source of the observed population difference in g. A more likely source is the microenvironment that produces the within-family variance. The macroenvironment consists of those aspects of interpersonal behavior, values, customs, preferences, and life-style to which children are exposed at home and which clearly differ between families and ethnic groups in American society. The microenvironment consists of a great many small, often random, events that take place in the course of prenatal and postnatal life. Singly they have small effects on mental development, but in the aggregate they may have a large cumulative effect on the individual. These microenvironmental effects probably account for most of the nongenetic variance in IQ that remains after childhood. [79]

79. The theory and empirical evidence for the microenvironmental component of IQ variance are spelled out in Jensen, 1997a.

Jensen A. R. ( 1997a). "The puzzle of nongenetic variance". In R. J. Sternberg & E. L. Grigorenko (Eds.) Intelligence, heredity and environment (http://www.amazon.com/exec/obidos/tg/detail/-/052146904X) (pp. 42-88). Cambridge: Cambridge University Press.(Arthur Jensen. The g Factor (http://www.questia.com/PM.qst?action=openPageViewer&docId=24373874). 1998. pp489, 527, 614.)

[iansmith]

Ian, the fraternal twins are other relatives. Fraternal twins are both not as genetically related as identical twins, and — unless adopted away — raised in the same environment (except the microenvironment of the home; see Jensen 1998 regarding home microenvironments).

What I meant was that you need more than 2 brothers to really look a heredity? Two brother does point necessarly to heridity. You need other relative such as cousin, uncle, aunts, grand-parents, etc.

[Mandrake]

Originally Posted by Mandrake
They show that if a man in prison has an identical twin, it's likely his cotwin will also be in prison. If the twin is fraternal [with 50 percent shared genes, on the average], the likelihood is not nearly as great that he'll be in prison, too, but it's greater than chance. How could one possibly account for this difference with environmentalist explanations? The strong genetic component in criminality has already been proven up to the hilt.
Iansmith: The problem here is that the example does not prove that there is genetic link. The environment could be in question. Two twin brother in prison. Both grew in the same environment. Was the parents, other relatives in prison?
I assume you understand that Cattell's example was intended to be understood as a statistical and not an anecdotal observation. When Cattell stated "The strong genetic component in criminality has already been proven up to the hilt," he was not implying that he had based that conclusion on a single observation, nor even on a set of personal observations. He was telling us that the subject has been reported in many sources and that the results are in agreement. Likewise, your family example, while interesting, is anecdotal.

The relationship of crime to IQ is also interesting. Cattell was not commenting on this, but it is discussed in The Bell Curve, in the chapter titled "Crime." [chapter 11] The discussion points out that criminal behavior correlates negatively with IQ. It should be noted that the content of chapters 1-12 in The Bell Curve are based entirely on a single population group (non-Latino whites).

To prove that the heredity exist, you have to compare the gifted against the average individuals at the genetic level.
The heritability of intelligence can be firmly established without examining ANY gifted individuals. Intelligence is heritable at all IQ levels. The mechanism for describing the heritability of intelligence is to find the mean for the parents and to locate the regression point between that mean and the population group mean. That point then becomes the mean value for the normal distribution that applies to the children of the parents in question.

Heredity can only be proven if there is genes associated with it.
This field of study is particularly associated with researcher Robert Plomin, who discovered IGF2R on chromosome 6. Whether or not the specific genes have been identified, heritability of a trait can be established. The concept of heredity was known long before genetic research identified any trait specific genes.

As for the heritability of intelligence, it is quantified by path analysis and by MZA studies. The data typically fall around h^2 = 72% for young adults, increasing to 80% for old adults. [These are variances, not r values.] Inbreeding depression studies show that intelligence behaves similarly to other traits that are depressed by inbreeding. The only explanation for this is a genetic cause. This one observation is so strong that it cannot be refuted by any amount of hand waving.

The other part of h^2 is the environmental component. This component has been studied in great detail for decades, including the conduct of costly and lengthy experiments. Adoption studies (including interracial ones) have shown that adopted children initially show some correlation to the mean IQs of their adoptive parents, but that this vanishes by late adolescence. As adults they resemble the IQs of their biological parents to approximately the same extent as do children who were reared by their biological parents. Adopted children have a tiny negative correlation to their adoptive siblings.

In adoption studies, such as the Texas Adoption Study (Loehlin, 1989), the IQ correlations between the biological mother (.26) and the adoptive mother (.05) show little evidence of environmental influence by teen years. Virtually all traces of environmental influence are gone (four adoption studies cited by Brand) by adulthood.

Intervention programs have attempted to alter the environmental component, but they have demonstrated that such efforts are doomed to failure. The final conclusion is obvious. Intelligence is determined genetically.

Once you have what you think is responsible then you have to compare it with other families with suspected heritable gifts.
Giftedness is not a requirement for h^2. Dumb people inherit their intelligence, just as do normal and bright people.

None of the research stated looked at the genetic level of the heredity.
I don't think your comment is accurate. You have made an assertion, but it is in disagreement with reality. Although some genes do not express themselves immediately, there is a strong early indication of the correlation between IQ and performance.
The _g_ Factor: General Intelligence and Its Implications:
"IQ rises in predictive value relative to other measures as years go on" (p.77). In a long-term follow-up of a random sample of state-school five-year-olds on the Isle of Wight, IQ correlated strongly (at .50) with children's later educational attainments, when they were fifteen. Such prediction for individuals across ten supposedly formative years is unparalleled in social science."

[Evo]

Heredity can only be proven if there is genes associated with it.
This field of study is particularly associated with researcher Robert Plomin, who discovered IGF2R on chromosome 6. Whether or not the specific genes have been identified, heritability of a trait can be established. The concept of heredity was known long before genetic research identified any trait specific genes.Plomin never succeeded, to date specific genes have not been identified, he gave up his research in this field.

[Moonbear]

In adoption studies, such as the Texas Adoption Study (Loehlin, 1989), the IQ correlations between the biological mother (.26) and the adoptive mother (.05) show little evidence of environmental influence by teen years. Virtually all traces of environmental influence are gone (four adoption studies cited by Brand) by adulthood.

And in 1989, the effect of maternal stress on the developing fetus were only beginning to be appreciated and not widely publicized yet. At the time, the majority of work on maternal-fetal interactions of that sort were focusing on alcohol consumption and smoking. I feel like I'm talking to the wall here. There are non-genetic reasons why offspring may be influenced by their birth mother that would affect behavior and/or intelligence. This is the major oversight in the twin and adoptive studies. Or, really, just that most of those studies were done before this interaction was understood. The conclusions may have made sense at the time those studies were done, but they have not withstood the test of time.



One more example:

Early Hum Dev. 2003 Nov;74(2):139-51.
Prenatal maternal cortisol levels and infant behavior during the first 5 months.
de Weerth C, van Hees Y, Buitelaar JK.

BACKGROUND AND AIMS: Research on both animals and humans is providing more and more evidence that prenatal factors can have long-term effects on development. Most human studies have examined the effects of prenatal stress on birth outcome (i.e. shorter pregnancies, smaller infants). The few studies that have looked at the infants' later development have found prenatal stress to be related to more difficult temperament, behavioral/emotional problems and poorer motor/cognitive development. In this paper, we have examined links between late pregnancy cortisol levels and infant behavior during the first 5 months of life. STUDY DESIGN AND SUBJECTS: Seventeen mothers and their healthy, full-term infants participated in this prospective, longitudinal study. The mothers' cortisol was determined in late pregnancy. The infants' behavior was videotaped during a series of bath sessions at the home: at 1, 3, 5, 7, 18 and 20 weeks of age. The mothers filled in temperament questionnaires (ICQ) in postnatal weeks 7 and 18. RESULTS AND CONCLUSIONS: The infants were divided into two groups based on their mothers' late pregnancy cortisol values: high and low prenatal cortisol groups. A trend was found for the high cortisol infants to be delivered earlier than the low cortisol group. Furthermore, the behavioral observations showed the higher prenatal cortisol group to display more crying, fussing and negative facial expressions. Supporting these findings, maternal reports on temperament also showed these infants to have more difficult behavior: they had higher scores on emotion and activity. The differences between the infants were strongest at the youngest ages (weeks 1-7).

PMID: 14580753 [PubMed - indexed for MEDLINE]

[iansmith]

The heritability of intelligence can be firmly established without examining ANY gifted individuals. Intelligence is heritable at all IQ levels. The mechanism for describing the heritability of intelligence is to find the mean for the parents and to locate the regression point between that mean and the population group mean. That point then becomes the mean value for the normal distribution that applies to the children of the parents in question.

Rather than using the entire distribution as in QTL studies of other personality traits (Benjamin et al., 2002), the IQ QTL Project selected very high-functioning individuals in order to increase power to detect QTLs of small effect size. Its goal is not to find genes for genius but rather to use very high-functioning individuals in order to identify QTLs that operate throughout the entire distribution, including the low (MMR) end of the ability distribution. This approach is based on the simple hypothesis that, although any one of many genes can disrupt normal development, very high functioning requires most of the positive alleles and few of the negative alleles. This is just a hypothesis, but one that can be tested when QTLs are found because it predicts that QTLs found for high ability will have a similar effect throughout the rest of the distribution including the low end of the distribution.


This field of study is particularly associated with researcher Robert Plomin, who discovered IGF2R on chromosome 6. Whether or not the specific genes have been identified, heritability of a trait can be established. The concept of heredity was known long before genetic research identified any trait specific genes.

....
I don't think your comment is accurate. You have made an assertion, but it is in disagreement with reality. Although some genes do not express themselves immediately, there is a strong early indication of the correlation between IQ and performance.
The _g_ Factor: General Intelligence and Its Implications:
"IQ rises in predictive value relative to other measures as years go on" (p.77). In a long-term follow-up of a random sample of state-school five-year-olds on the Isle of Wight, IQ correlated strongly (at .50) with children's later educational attainments, when they were fifteen. Such prediction for individuals across ten supposedly formative years is unparalleled in social science."

There have been no traditional linkage studies of intelligence or other quantitative traits, although, as mentioned earlier, linkage has been successful in leading to the identification of more than 200 rare single-gene syndromes for which mental retardation is a symptom (Zechner et al., 2001).

The earlier survey of 100 markers also included two markers for the catechol-o-methyltransferase gene (COMT) that did not suggest associations (Plomin et al., 1995). The COMT gene has been reported recently to correlate with working memory (Egan et al., 2001), which is highly correlated with intelligence (Deary, 2001).

All quote are from
Intelligence, Genetics, Genes, and Genomics
Robert*Plomin and Frank M.*Spinath
http://content.apa.org/journals/psp/86/1/112.html#c92
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=14717631

[Evo]

In adoption studies, such as the Texas Adoption Study (Loehlin, 1989), the IQ correlations between the biological mother (.26) and the adoptive mother (.05) show little evidence of environmental influence by teen years. Virtually all traces of environmental influence are gone (four adoption studies cited by Brand) by adulthood.

Intervention programs have attempted to alter the environmental component, but they have demonstrated that such efforts are doomed to failure. The final conclusion is obvious. Intelligence is determined genetically.As Moonbear pointed out, your information is outdated and newer studies have proven just the opposite.

The recent study by Turkheimer of the interaction among genes, environment and IQ finds that the influence of genes on intelligence is dependent on class and that environmental factors -- not genetic deficits -- explain IQ differences among poor minorities.

The study was published in the November 2003 issue of the journal Psychological Science. Here is the abstract.

Scores on the Wechsler Intelligence Scale for Children were analyzed in a sample of 7 year old twins from the National Collaborative Perinatal Project. A substantial proportion of the twins were raised in families living near or below the poverty level. Biometric analyses were conducted using models allowing for components attributable to the additive effects of genotype, shared environment, and non-shared environment to interact with socioeconomic status (SES) measured as a continuous variable. Results demonstrate that the proportions of IQ variance attributable to genes and environment vary nonlinearly with SES. The models suggest that in impoverished families, 60% of the variance in IQ is accounted for by the shared environment, and the contribution of genes is close to zero; in affluent families, the result is almost exactly the reverse.

Here is a link to the study. http://www.people.virginia.edu/~ent3c/papers2/Turkheimer%20psychological%20science.pdf

[nuenke]

The recent study by Turkheimer of the interaction among genes, environment and IQ finds that the influence of genes on intelligence is dependent on class and that environmental factors -- not genetic deficits -- explain IQ differences among poor minorities.

It is well known that intelligence is more malleable in children, and more genetic in adults. Any study that does not test the children later on in life is quite meaningless with regards to intelligence in adulthood. We all know, including the Jensenists, that there is a great deal of environmental influence on children's IQ, but it fades as they grow up.

Frankly, there has not been a coherent alternative to Jensenism. Every attempt to link adult intelligence to environmental causes, except a small percentage of IQ varaince, has failed over and over again. The environmental causation of intelligence is not only unsubstantiated, it has yet to put forth a verifiable, and testable hypothesis as to how it occurs. There are too many theories, all too complex, when the genetic one is the most parsimonious and long-standing theory of individual and racial differences in intelligence.

[Evo]

Every attempt to link adult intelligence to environmental causes, except a small percentage of IQ varaince, has failed over and over again.That would concur with what Turkheimer is saying, no previous studies were done on impoverished children, which is where the difference is.

Please post the peer reviewed studies that followed impoverished children that were then given proper care, nutrition and placed in higher SES homes and showed improved IQs as a result that were then tested as adults and showed a decline in IQ. I haven't seen any.

[Mandrake]

Originally Posted by Mandrake
In adoption studies, such as the Texas Adoption Study (Loehlin, 1989), the IQ correlations between the biological mother (.26) and the adoptive mother (.05) show little evidence of environmental influence by teen years. Virtually all traces of environmental influence are gone (four adoption studies cited by Brand) by adulthood.

Intervention programs have attempted to alter the environmental component, but they have demonstrated that such efforts are doomed to failure. The final conclusion is obvious. Intelligence is determined genetically.

As Moonbear pointed out, your information is outdated and newer studies have proven just the opposite.

The recent study by Turkheimer of the interaction among genes, environment and IQ finds that the influence of genes on intelligence is dependent on class and that environmental factors -- not genetic deficits -- explain IQ differences among poor minorities.

I noticed that you presented the Turkheimer paper before and even hounded one participant here about it. The problem is that you don't appear to understand what it does and does not demonstrate. Turkheimer does not present any data for cohorts beyond the age of 7. Intervention studies and adoption studies have consistently found environmental influences that cause IQ in the subjects to improve relative to their peers in childhood. The heritability of IQ in the range Turkheimer studied is typically reported as .40. The gains at age 7 seen by adoption led Scarr to reach the conclusion that she had predicted in advance of her research -- that the adopted children would see a boost in intelligence. But Scarr acted as a responsible scientist and evaluated the same adoptees when they reached the age of 17. She found no residual gains. She and Weinberg concluded that within the range of "humane environments," variations in family socioeconomic characteristics and in
child-rearing practices have little or no effect on IQ measured in adolescence. They claim that most "humane environments" are functionally equivalent for mental development.

Among the things that you should have told us, but didn't:
1 - That the study included only young children and does not make any attempt to extrapolate that all other findings of significant increases in h^2 by age 17 are in any way invalid.
2 - That Turkheimer began his paper by recognizing that the heritability of cognitive ability in childhood is well established.
3 - That Turkheimer made no attempt whatsoever to determine what components of SES he was measuring. There are three obvious items to consider: macro environmental, micro environmental, and genetic. All work to date indicates that the first of these can be found in children, but that it is absent in late adolescents; that by late adolescence, all of the environmental component is of the second type; and that genetic intelligence is the largest determinant of SES.
4 - That Turkheimer says that the effect he observed was related to the homes in which the children were raised. This is interesting, since it relates to the adoption studies which show that after childhood there is no correlation between biologically unrelated children who were reared together in the same home.
5 - That Turkheimer discusses in some detail that SES is not strictly an environmental variable, since it is known to be (statistically) caused by the intelligence of the parents. He points out that the models he used "cannot determine which aspect of SES is responsible for the interactions" observed.
6 - You wrote: "The recent study by Turkheimer of the interaction among genes, environment and IQ finds that the influence of genes on intelligence is dependent on class and that environmental factors -- not genetic deficits -- explain IQ differences among poor minorities." I dispute that his paper says any such thing. His discussion was strictly based on SES and did not single out "poor minorities." The children he studied were listed as white, black, and "other." I believe your comment is a misrepresentation.

The bottom line is that you have attempted (in prior threads) to use this study as a club, while apparently not understanding it. There is nothing in this study that contradicts the items I have presented in this forum.

[Mandrake]

Related to the discussion of children, as having a different envrionmental component to the phenotype:

Genetics and intelligence: What's new?
Intelligence, Volume 24, Issue 1, January-February 1997, Pages 53-77
Robert Plomin and Stephen A. Petrill

In this paper, the shared environment variance is given as 25% in childhood and zero after adloscence.

[Mandrake]

Originally Posted by Mandrake
In adoption studies, such as the Texas Adoption Study (Loehlin, 1989), the IQ correlations between the biological mother (.26) and the adoptive mother (.05) show little evidence of environmental influence by teen years. Virtually all traces of environmental influence are gone (four adoption studies cited by Brand) by adulthood.


And in 1989, the effect of maternal stress on the developing fetus were only beginning to be appreciated and not widely publicized yet. At the time, the majority of work on maternal-fetal interactions of that sort were focusing on alcohol consumption and smoking.
Conditions in the intrauterine environment have been known as a micro environmental factor for a very long time. There has not been any denial that various such conditions can adversely affect intelligence. This component, combined with whatever other micro environmental components the individual faces does not cause the entire body of statistics relating to heritability to change. The IQ gap between blacks and all other population groups has been measured for the past century and has remained reasonably constant. It remains even when the blacks in question come from the highest SES decile.

I feel like I'm talking to the wall here.
I suspect that you are talking to yourself and you have convinced your audience that you understand the subject much better than one would conclude by reading the above comments. You have not shown any linkage between maternal stress and the Texas Adoption Study, or any of the numerous other similar studies that gave similar results. Instead, you are asserting that those studies were done by incompetent people and that the results were tainted. I see no evidence that the link you want to see is real.

There are non-genetic reasons why offspring may be influenced by their birth mother that would affect behavior and/or intelligence.

Yes. I agree. Jensen has commented that the majority of environmental factors are those that decrease intelligence. When someone gives a value of h^2 as 72%, what do you think accounts for the remaining 28%?

This is the major oversight in the twin and adoptive studies.

That assertion covers a huge amount of ground. It assumes that twin studies contain stresses that were not reported. So, if you have a MZA study that reports h^2 at 70 or so percent, what do you conclude? That stress did what? How does maternal stress enter into a MZA study? Does it cause the value of h^2 to increase or decrease and why?

Or, really, just that most of those studies were done before this interaction was understood. The conclusions may have made sense at the time those studies were done, but they have not withstood the test of time.
In what way have they not withstood the test of time? When MZA studies produce h^2 that is virtually identical to the values calculated by path analysis, any error you suggest must have equally affected both methods. Right? I contend that such an argument is outrageous and impossible.

[hitssquad]

This field of study is particularly associated with researcher Robert Plomin, who discovered IGF2R on chromosome 6.Plomin never succeeded, to date specific genes have not been identified, he gave up his research in this field.When did Plomin give up his research (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed&term=plomin+r) in this field?


Mol Psychiatry. 2004 Jun;9(6):582-6.

A functional polymorphism in the succinate-semialdehyde dehydrogenase (aldehyde dehydrogenase 5 family, member A1) gene is associated with cognitive ability.

Plomin R, Turic DM, Hill L, Turic DE, Stephens M, Williams J, Owen MJ, O'Donovan MC.

Social Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, De Crespigny Park, Denmark Hill, London, UK.

Succinate-semialdehyde dehydrogenase (SSADH) deficiency is a rare cause of learning disability. We have investigated SSADH to assess its contribution to cognitive ability in the general population in both case-control- and family-based analyses. Sequence analysis of SSADH revealed four changes affecting the encoded protein, only one of which had a minor allele whose frequency is even moderately common. We genotyped this functional polymorphism in 197 high-IQ cases, 201 average-IQ controls and 196 parent high-IQ offspring trios. The minor allele was significantly less frequent in high-IQ cases and was significantly less frequently transmitted by parents to high-IQ subjects than chance expectation. A previous study has shown that the minor allele encodes a lower activity enzyme than the major allele. These data suggest that higher SSADH activity is associated with higher intelligence across the general population. The effect is small, with each allele having an effect size translating to about 1.5 IQ points.

PMID: 14981524 (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=14981524)



Behav Genet. 2004 Sep;34(5):549-55 (http://content.kluweronline.com/article/491329/fulltext.pdf).

Genotyping Pooled DNA on Microarrays: A Systematic Genome Screen of Thousands of SNPs in Large Samples to Detect QTLs for Complex Traits.

Butcher LM, Meaburn E, Liu L, Fernandes C, Hill L, Al-Chalabi A, Plomin R, Schalkwyk L, Craig IW.

Social,Genetic and Developmental Psychiatry Centre, Box Number P082, Institute of Psychiatry, De Crespigny Park, London, SE5 8AF, UK.

Large samples and systematic screens of thousands of DNA markers are needed to detect quantitative trait loci (QTLs) of small effect size. One approach to conduct systematic genome scans for association is to use microarrays which, although expensive and non-reusable, simultaneously genotype thousands of single-nucleotide polymorphisms (SNPs). This brief report provides proof of principle that groups of pooled DNA (for example cases and controls) can be genotyped reliably on a microarray. DNA was pooled for 105 Caucasian males and genotyped three times on microarrays for more than 10,000 SNPs (Affymetrix GeneChip(R) Mapping 10K Array Xba 131). The average correlation was 0.973 between the allele frequency estimates for the three microarrays using the same DNA pool. The correlation was 0.923 between the average of the three microarray estimates using pooled DNA and individual genotyping estimates for a Caucasian population as provided by Affymetrix (NetAff(x)(TM)). Thus, genotyping pooled DNA on microarrays can provide a systematic and powerful approach for identifying QTL associations for complex traits including behavioral dimensions and disorders.

PMID: 15319578 (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15319578)

[Evo]

Turkheimer does not present any data for cohorts beyond the age of 7. Intervention studies and adoption studies have consistently found environmental influences that cause IQ in the subjects to improve relative to their peers in childhood. The heritability of IQ in the range Turkheimer studied is typically reported as .40. The gains at age 7 seen by adoption led Scarr to reach the conclusion that she had predicted in advance of her research -- that the adopted children would see a boost in intelligence. But Scarr acted as a responsible scientist and evaluated the same adoptees when they reached the age of 17. She found no residual gains. She and Weinberg concluded that within the range of "humane environments," variations in family socioeconomic characteristics and in
child-rearing practices have little or no effect on IQ measured in adolescence. They claim that most "humane environments" are functionally equivalent for mental development.His study was not based on Scarr's study, his study was based on this. In the current study, we used data from the National Collaborative Perinatal Project, which included a large national sample of American mothers, who were enrolled into the study during pregnancy (n48,197), and their children (n59,397), who were followed from birth until age 7 (Nichols & Chen, 1981). Participants were recruited from 12 urban hospitals around the country and included a high proportion of racial minorities and impoverished families.

Among the things that you should have told us, but didn't:
1 - That the study included only young children and does not make any attempt to extrapolate that all other findings of significant increases in h^2 by age 17 are in any way invalid.Wrong, first sentence of the abstract Scores on the Wechsler Intelligence Scale for Children were analyzed in a sample of 7 year old twins from the National Collaborative Perinatal Project. And again, you are referring to a different study.

2 - That Turkheimer began his paper by recognizing that the heritability of cognitive ability in childhood is well established.Here is what he said - Although the heritability of cognitive ability in childhood is well established (McGue, Bouchard, Iacono, & Lykken, 1993; Plomin, 1999),the magnitude, mechanisms, and implications of the heritability of IQ remain unresolved. You forgot the last half of the sentence?

3 - That Turkheimer made no attempt whatsoever to determine what components of SES he was measuring. There are three obvious items to consider: macro environmental, micro environmental, and genetic. All work to date indicates that the first of these can be found in children, but that it is absent in late adolescents; that by late adolescence, all of the environmental component is of the second type; and that genetic intelligence is the largest determinant of SES.Turkheimer goes into great detail about his methods. If you read Methods & Discussion you may understand. These findings suggest that a model in which variability in intelligence among children is partitioned into independent components attributable to genes and environments is too simple for the dynamic interaction of genes and real-world environments during development.The relative importance of environmental differences in causing differences in observed intelligence appears to vary with the SES of the homes in which children were raised. SES is a complex variable, however, and the substantive interpretation to be placed on our results depends on an interpretation of what SES actually measures. The most obvious interpretation of SES in this study is that it measured the quality of the environment in which the children were born and raised. Indeed, this is the function for which SES was intended. Under this interpretation, the observed interaction between SES and the biometric components of IQ could be indicative of precisely the kind of nonlinear relationship between rearing environment and intelligence that has been suggested by Scarr (1981) and Jensen (1981), with differences among poor environments contributing more to differences in phenotypic outcome than differences among middle class or better environments contribute. It would be naive, however, to interpret SES strictly as an environmental variable. Most variables traditionally thought of as markers of environmental quality also reflect genetic variability (Plomin & Bergeman, 1991). Children reared in low-SES households, therefore, may differ from more affluent children both environmentally and genetically (Gottesman, 1968), and the models we employed in this study do not allow us to determine which aspect of SES is responsible for the interactions we observed. Indeed, it will be difficult to separate the genetic and environmental aspects of SES or other measures of the family environment in research designs of this kind, because children raised in the same home necessarily have the same SES.

Genetic variability in SES might also introduce a complication to the models themselves. Phenotypic SES and IQ are correlated, and that correlation is potentially mediated both genetically and environmentally. Therefore, the models are attempting to detect an interaction between genotype and environment in the presence of a correlation between genotype and environment, raising the concern that the presence of the correlation might introduce bias into the estimation of the interaction. However, Purcell (2003) has conducted an exhaustive series of simulations that suggest no bias is introduced, as long as the main effect of the moderating variable is included in the model, as we have done here. The presence in the model of the main effect of SES means that the biometric model fitting is actually being conducted on the portion of IQ that is independent of both the genetic and environmental components of SES. (We note, however, that omitting the main effect from the model did not change the results to a significant degree.

4 - That Turkheimer says that the effect he observed was related to the homes in which the children were raised. This is interesting, since it relates to the adoption studies which show that after childhood there is no correlation between biologically unrelated children who were reared together in the same home.This study is unique in that it is based upon impoverished households, something that has not previously been studied. Why do you keep bringing up earlier unrelated studies that this study supercedes?

5 - That Turkheimer discusses in some detail that SES is not strictly an environmental variable, since it is known to be (statistically) caused by the intelligence of the parents. He points out that the models he used "cannot determine which aspect of SES is responsible for the interactions" observed.Ah, you did read it.

6 - You wrote: "The recent study by Turkheimer of the interaction among genes, environment and IQ finds that the influence of genes on intelligence is dependent on class and that environmental factors -- not genetic deficits -- explain IQ differences among poor minorities." I dispute that his paper says any such thing. His discussion was strictly based on SES and did not single out "poor minorities." The children he studied were listed as white, black, and "other." I believe your comment is a misrepresentation.That does not preclude poor minorities.

The bottom line is that you have attempted (in prior threads) to use this study as a club,What, because it doesn't agree with you? I really think you need to retract that statement as well as the earlier statement you made. Why do you insist on personal attacks?

There is nothing in this study that contradicts the items I have presented in this forum.It probably contradicts most of what you have posted on this forum.

[Evo]

When did Plomin give up his research (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed&term=plomin+r) in this field?Oh, you're right, I am guilty of not reading that closely and was thinking of Plomin's attempt to identify genes linked to IQ.

[Mandrake]

Originally Posted by Mandrake
Turkheimer does not present any data for cohorts beyond the age of 7. Intervention studies and adoption studies have consistently found environmental influences that cause IQ in the subjects to improve relative to their peers in childhood. The heritability of IQ in the range Turkheimer studied is typically reported as .40. The gains at age 7 seen by adoption led Scarr to reach the conclusion that she had predicted in advance of her research -- that the adopted children would see a boost in intelligence. But Scarr acted as a responsible scientist and evaluated the same adoptees when they reached the age of 17. She found no residual gains. She and Weinberg concluded that within the range of "humane environments," variations in family socioeconomic characteristics and in child-rearing practices have little or no effect on IQ measured in adolescence. They claim that most "humane environments" are functionally equivalent for mental development.

Evo: His study was not based on Scarr's study, his study was based on this.
I did not claim that his study was based on Scarr's study. I pointed out the important fact that this study was limited to children up to 7 years old. When Scarr did her work, she reached one conclusion when she evacuated her subjects at age 7 and then reversed her conclusion when she tested them again at age 17. Her finding is consistent with all other longitudinal studies in demonstrating that the shared environment component vanishes after age 7 and before age 17.

In the current study, we used data from the National Collaborative Perinatal Project,
Thank you. I have read and understood the paper. Whether or not you have read it, your comments indicate that you do not understand it nor how it fits into the big picture.

Quote:
Originally Posted by Mandrake
Among the things that you should have told us, but didn't:
1 - That the study included only young children and does not make any attempt to extrapolate that all other findings of significant increases in h^2 by age 17 are in any way invalid.
Evo: Wrong, first sentence of the abstract Scores on the Wechsler Intelligence Scale for Children were analyzed in a sample of 7 year old twins from the National Collaborative Perinatal Project. And again, you are referring to a different study.
The study I have read is from Psychological Science, vol. 14, No. 6, Nov. 2003. There is no extrapolation of any finding in that paper to heritability beyond the age of 7. As such, the entire study is of interest only with respect to young children and says nothing about children past the age of 7. All prior research shows that the shared environment component of heritability completely vanishes by age 17.

Quote:
Originally Posted by Mandrake
2 - That Turkheimer began his paper by recognizing that the heritability of cognitive ability in childhood is well established.
Evo: Here is what he said - Although the heritability of cognitive ability in childhood is well established (McGue, Bouchard, Iacono, & Lykken, 1993; Plomin, 1999),the magnitude, mechanisms, and implications of the heritability of IQ remain unresolved. You forgot the last half of the sentence?
I didn't quote the sentence. What part of the material you quoted is significant and derived from the study?

Quote:
Originally Posted by Mandrake
3 - That Turkheimer made no attempt whatsoever to determine what components of SES he was measuring. There are three obvious items to consider: macro environmental, micro environmental, and genetic. All work to date indicates that the first of these can be found in children, but that it is absent in late adolescents; that by late adolescence, all of the environmental component is of the second type; and that genetic intelligence is the largest determinant of SES.

Turkheimer goes into great detail about his methods.
That is not what I challenged. You don't understand what he wrote do you? The material you quoted below is precisely the point of my comment.

SES is a complex variable, however, and the substantive interpretation to be placed on our results depends on an interpretation of what SES actually measures. ... Most variables traditionally thought of as markers of environmental quality also reflect genetic variability (Plomin & Bergeman, 1991). Children reared in low-SES households, therefore, may differ from more affluent children both environmentally and genetically (Gottesman, 1968), and the models we employed in this study do not allow us to determine which aspect of SES is responsible for the interactions we observed. Indeed, it will be difficult to separate the genetic and environmental aspects of SES or other measures of the family environment in research designs of this kind, because children raised in the same home necessarily have the same SES.

Quote:
Originally Posted by Mandrake
4 - That Turkheimer says that the effect he observed was related to the homes in which the children were raised. This is interesting, since it relates to the adoption studies which show that after childhood there is no correlation between biologically unrelated children who were reared together in the same home.
This study is unique in that it is based upon impoverished households, something that has not previously been studied. Why do you keep bringing up earlier unrelated studies that this study supersedes?
His study does not supersede anything. It is a study that includes low SES people who have produced lower heredity scores than found in other studies, but under circumstances that the researcher cannot separate from pure genetic or mixed genetic factors. He did not suggest that there is any reason to expect the subjects of his study to mature by a different path than all of the other children who have been studied by longitudinal studies.

Quote:
Originally Posted by Mandrake
5 - That Turkheimer discusses in some detail that SES is not strictly an environmental variable, since it is known to be (statistically) caused by the intelligence of the parents. He points out that the models he used "cannot determine which aspect of SES is responsible for the interactions" observed.
Ah, you did read it.
And, unlike some folks, I understood it.

Quote:
Originally Posted by Mandrake
6 - You wrote: "The recent study by Turkheimer of the interaction among genes, environment and IQ finds that the influence of genes on intelligence is dependent on class and that environmental factors -- not genetic deficits -- explain IQ differences among poor minorities." I dispute that his paper says any such thing. His discussion was strictly based on SES and did not single out "poor minorities." The children he studied were listed as white, black, and "other." I believe your comment is a misrepresentation.

That does not preclude poor minorities.
You don't appear to understand the material. There was no attempt to study poor minorities, nor was there any attempt to separate the cohorts and study them separately. NONE of the data are based on a single "minority" or population group or race.

Quote:
Originally Posted by Mandrake
The bottom line is that you have attempted (in prior threads) to use this study as a club,
What, because it doesn't agree with you?
You badgered bobf with the article (even though you do not show any appreciation of it) on dates that preceded my joining the discussion forum.

I really think you need to retract that statement as well as the earlier statement you made. Why do you insist on personal attacks?
My statement is a simple matter of the record. I have not attacked you personally, I have pointed out the errors in what you have posted.

Quote:
Originally Posted by Mandrake
There is nothing in this study that contradicts the items I have presented in this forum.

It probably contradicts most of what you have posted on this forum.

Really? I don't think so. I challenge you to quote my prior comments and to then demonstrate that the study contradicts them. Good luck.

[Evo]

Mandrake, this study is groundbreaking, this population segment has never been studied before in this way, therefore none of your outdated studies are relevant to this. Unless you have some recent studies that are based on the same impoverished level of participants, you don’t have an argument against his study. This is all new. Only time will tell.

I think it is wonderful news that children can be helped, don't you?

As Turkheimer himself concluded - In the fractious history of scientific investigations of the heritability of intelligence, the effects of poverty, and the relations between them, there has been only one contention with which everyone could agree: Additive models of linear and independent contributions of genes and environment to variation in intelligence cannot do justice to the complexity of the development of intelligence in children. Only recently have statistical models and computational capacity advanced to the point that less simplistic models can actually be fit. Although there is much that remains to be understood, our study and the ones that have preceded it have begun to converge on the hypothesis that the developmental forces at work in poor environments are qualitatively different from those at work in adequate ones. Clarification of the nature of these differences promises to be a fascinating, and hopefully unifying, subject for future investigation.

[Nereid]

Intelligence appears to have at least some negative correlation with parity.How much (range)? How extensively has this been tested?Would you expect psychometricians from New Zealand, England, Canada, and Germany to arrive at different findings?I'm taking this step-by-step, and per hitssquad's Jensen quote, _g_ correlations are most solidly demonstrated in the US.Who are these people? Can you name a few of the better known ones?You really threw me with this one! :surprise: Aren't you the psychometrician?

Anyway, here are some (non-intelligence) 'psychometric instruments' that I found by doing some googling:
- 16 PF5 ("Based on Cattell's trait theory of personality, this instrument has been adapted for use within organisations.")
- Myers-Briggs ("Based on Jung's type theory of personality, developed by Isabel Myers and Katherine Briggs.")
- Strong's Career Interest inventory ("based on Holland's typology of activities. The theory agues that individuals differ in the degree to which they have a preference for certain activities and that jobs contain these activities in varying degrees")
- Team Climate Inventory ("developed by Anderson and West (1996) allows objective comparison of the way teams function").

I also found references to DISC ("DISC measures four factors of an individual's behaviour: Dominance, Influence, Steadiness and Compliance. They can be characterised as assertiveness, communication, patience and structure.")

Finally, this university site (http://www.newcastle.edu.au/school/behav-sci/facilities/psyclib/) has a looong list of psychometric tests, of which only a small subset seem to be 'intelligence tests'.

[hitssquad]

When did Plomin give up his research (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed&term=plomin+r) in this field?Oh, you're right, I am guilty of not reading that closely and was thinking of Plomin's attempt to identify genes linked to IQ.I was also thinking of the attempt by Plomin to identify genes linked to IQ. My link (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed&term=plomin+r) to his current research would seem to belie any speculation that he has given up his IQ-gene research — or are you making distinctions between QTL's, alleles and genes?

Did Robert Plomin give up his attempt to identify genes linked to IQ?

[Mandrake]

Oh, you're right, I am guilty of not reading that closely and was thinking of Plomin's attempt to identify genes linked to IQ.
So far, hitsquad seems to be telling you that you have ducked his question.

For the benefit of anyone interested, Jensen: "At least four genes or DNA segments that affect IQ have been identified by behavior geneticist Robert Plomin of the Institute of Psychiatry of the University of London. And his investigation continues." [Miele (2002) - Intelligence, Race, and Genetics: Conversations with Arthur R. Jensen, P. 103]

If your comment is correct, please substantiate it. If it is incorrect, you might want to admit your error more clearly.

[Evo]

Did Robert Plomin give up his attempt to identify genes linked to IQ?According to an article I read and his home page. He's shifted his focus to another study for now. He never published his findings on his studies linking genes to IQ. I believe there are some others that have picked up that research. The link you posted appears to be related to his current research.

From your link - "Thus, genotyping pooled DNA on microarrays can provide a systematic and powerful approach for identifying QTL associations for complex traits including behavioral dimensions and disorders."

From his website -

"Plomin is currently conducting a study (TEDS) of all twins born in England during the period 1994 to 1996, focussing on developmental delays in early childhood and their association with behavioural problems."

"The Twins Early Development Study (TEDS) represents Robert Plomin's major current research effort, funded as a programme grant by the UK Medical Research Council. "

http://www.robertplomin.com/

[BlackVision]

The recent study by Turkheimer of the interaction among genes, environment and IQ finds that the influence of genes on intelligence is dependent on class and that environmental factors -- not genetic deficits -- explain IQ differences among poor minorities.
Well you ducked this question before but might as well try again. What factors did the Turkheimer take into consideration that a higher IQed individual will be more likely to be in higher SES due to the fact that one's IQ level effects one's ability to be in a certain SES level? Rather than the vice versa of SES level effecting IQ. Without taking in such factors, any conclusions by this study will be considered void.

As I've said before, this study is similar to another study showing that college graduates have an IQ of 110. And then trying to claim that going to college effects your IQ. Rather than the more correct answer that it's their IQ that allowed them to go to college. It's using faulty logic and working backwards.

[Mandrake]

Originally Posted by Mandrake
Intelligence appears to have at least some negative correlation with parity.

How much (range)? How extensively has this been tested?
I don't know. It is something that I have seen mentioned in various books and papers as part of the discussion of within family variance. Unfortunately, Jensen's books are rather poorly indexed (unlike The Bell Curve) so it is always difficult to find material in them.

Miller says that the levels of testosterone that children are exposed to may be related to parity. Presumably he meant the intrauterine environment.

Searching my files didn't work. The problems involve multiple meanings of the term "parity" and the difficulty in removing "disparity" from the search.

Mandrake: Who are these people? Can you name a few of the better known ones?
Nereid: You really threw me with this one! Aren't you the psychometrician?
I am a physicist with a strong interest in psychometrics. I know the people who deal with intelligence, but that's it. I am familiar with the Myers-Briggs test you listed, but it only relates to intelligence in that intelligent people tend to have a profile that is not common in the general population (INTJ). Adding INTJ and INTP, accounts for 75% of the Mensa level population (per Mensa's report).

[Mandrake]

Mandrake, this study is groundbreaking, this population segment has never been studied before in this way, therefore none of your outdated studies are relevant to this.
Your comments on this single study reveal that you do not understand it nor do you understand how it relates to the rest of the literature. If you think any item I have discussed here is outdated as a result of the study (you have said that ALL were), I challenge you (again) to quote my comments and then show how they are now in error. You didn't accept my challenge before and I doubt that you will now. It is quite evident that you have an attitude, but are not appropriately informed to justify that attitude.

I think it is wonderful news that children can be helped, don't you?
The findings of the study were limited to the conclusion that genetic expression may be influenced by SES. The investigators were unable to even sort out genetic from non-genetic factors and said so. What "help" do you think they discussed in their paper? Do you think that they reported any increase in any child due to any aspect of their study?

Your obvious failure to understand this study has caused you to make statements here that are nonsense. You even used your assumed understanding to badger bobf concerning the paper. That strikes me as absolutely amazing!

[Evo]

Well you ducked this question before but might as well try again. What factors did the Turkheimer take into consideration that a higher IQed individual will be more likely to be in higher SES due to the fact that one's IQ level effects one's ability to be in a certain SES level? Rather than the vice versa of SES level effecting IQ. Without taking in such factors, any conclusions by this study will be considered void.He addresses that here - Phenotypic SES and IQ are correlated, and that correlation is potentially mediated both genetically and environmentally. Therefore, the models are attempting to detect an interaction between genotype and environment in the presence of a correlation between
genotype and environment, raising the concern that the presence of the correlation might introduce bias into the estimation of the interaction. However, Purcell (2003) has conducted an exhaustive series of simulations that suggest no bias is introduced, as long as the main effect of the moderating variable is included in the model, as we have done here. The presence in the model of the main effect of SES means that the biometric model fitting is actually being conducted on the portion of IQ that is independent of both the genetic and environmental components of SES. (We note, however, that omitting the main effect from the model did not change the results to a significant degree.)

[hitssquad]

Unfortunately, Jensen's books are rather poorly indexed (unlike The Bell Curve) so it is always difficult to find material in them.Jensen's 1980 book Bias in Mental Testing (http://www.amazon.com/exec/obidos/tg/detail/-/0029164303) seems to me to have a good index. But, unfortunately, it is not published on the web. Jensen's 1998 book The g Factor (http://www.questia.com/PM.qst?a=o&d=24373874), on the other hand, does have, it seems to me, a poor index, but the fact that Questia (subscription cost at the yearly rate equals 33 cents per day) publishes it on the web makes that somewhat moot since Questia has an in-book search function that even non-subscribers are allowed to use. If you at least own the physical book, you can use the Questia search function as an index to help you find things in the book.

[Evo]

Your comments on this single study reveal that you do not understand it nor do you understand how it relates to the rest of the literature. If you think any item I have discussed here is outdated as a result of the study (you have said that ALL were), I challenge you (again) to quote my comments and then show how they are now in error. You didn't accept my challenge before and I doubt that you will now. It is quite evident that you have an attitude, but are not appropriately informed to justify that attitude. Mandrake you keep quoting form the same old studies that everyone else has. You are the one that comes unglued if someone posts information that you disagree with. Feel free to attck the material I post, you may prove it wrong. You may not, however, attack me personally for posting a conflicting view.

The findings of the study were limited to the conclusion that genetic expression may be influenced by SES. The investigators were unable to even sort out genetic from non-genetic factors and said so. What "help" do you think they discussed in their paper? Do you think that they reported any increase in any child due to any aspect of their study?The study shows that environment is a substantially significant factor in increased IQ in the children studied and they are continuing this study.

Your obvious failure to understand this study has caused you to make statements here that are nonsense. You even used your assumed understanding to badger bobf concerning the paper. That strikes me as absolutely amazing!Your opinion means nothing to me Mandrake. No, I was trying to get BV to answer my questions, which he kept "dodging".

[Evo]

I am familiar with the Myers-Briggs test you listed, but it only relates to intelligence in that intelligent people tend to have a profile that is not common in the general population (INTJ). Adding INTJ and INTP, accounts for 75% of the Mensa level population (per Mensa's report).Myers-Briggs and DISC are both personality tests. Every few years at work we are required to take them. I have been both an INTJ and an INTP in Myers Briggs. My DISC test last year I was a D with a High I. The test before that the two were reversed.

[Moonbear]

Hitssquad, or whoever first brought up Plomin, that's some interesting work. I read his most recent article (the one in Behavior Genetics) this morning while drinking my coffee (admittedly, skimming through some parts quickly), and found it pretty interesting and solid. I especially liked that he had multiple analyses and what seemed to be a good control, which unfortunately threw a monkey wrench into the works. But at least he addressed it candidly and gave some different possible explanations, which I personally found very satisfying in the way they were discussed. I also liked that he took the reasonable approach of starting out with as homogeneous a study population a possible, with the exception of IQ being either high or average. This seemed to remove a lot of the possible confounds. He managed to address each of the questions/potential criticisms I raised in my own mind as I was reading.

[nuenke]

Are you familiar with the book "The Relationship Code: Deciphering Genetic and Social Influences on Adolescent Development" by Reiss, Neiderhiser, Hertherton and Plomin, 2000. It reports on a massive 13 year study funded by NIH, and supports the loss of shared environmental influence on a host of behaviors as children grow, including IQ (they used a proxy). I have excerpts I can email you. I have seen little of this study floating around, perhaps because it is so damaging to the environmentalists.

[BlackVision]

No, I was trying to get BV to answer my questions, which he kept "dodging".
Exactly which questions am I "dodging"? What an ironic accusation coming from you.

[Moonbear]

Nuenke, I wasn't familiar with it, so just went over to Amazon and looked it up. They had excerpts there, so I read those and the reviews of the book (it's currently out of print). From the excerpts there, it doesn't sound like the authors are saying environmental influences are lost at all. Instead, it seems to be suggesting a fairly reasonable argument that underlying genetic predisposition and environmental factors interact with one another to influence adolescent behavior. From the excerpts there, I can't tell if they are strictly limiting environmental factors to social factors or other non-genetic biological influences, or if those are more likely to wind up lumped in with the genetic factors. Do your excerpts say something different?

[Mandrake]

Mandrake you keep quoting form the same old studies that everyone else has.
Unfortunately, you have not been able to understand that (with rare exceptions) I have not been discussing early childhood in my messages. The study which has overwhelmed you deals only with children up to the age of 7. There is nothing in the paper that projects beyond that age. There is considerable material in peer reviewed sources which suggests that all shared environmental components of intelligence vanish after age 7 and before age 17. You have made numerous comments that you apparently think are related to the Turkheimer paper, which are purely figments of your imagination. One, is your comment about "helping" children. That subject was not discussed in the paper. I asked you about it, but you (as usual) ducked my question. You said that all of my prior comments were invalid because of this paper. The fact is that none are invalid because of the paper. For the third time, I challenge you to simply cut and past my comments from this thread (there are plenty) and show how each of them is invalidated by Turkheimer. You can't do it, but it will be fun to watch you try, or to duck it yet again.

The study shows that environment is a substantially significant factor in increased IQ in the children studied and they are continuing this study.
Is I have reminded you before, your comments suggest a lack of understanding. The paper shows only that very low SES (a high proportion of impoverished families) causes a large variance in heritability among very young children. Of the 4 tests that were conducted, two were significantly below the age that testing is considered to be reliable (that age is 3, while tests were done at 8 months and 1 year). The study did not state ANYTHING about the influence of environment for higher than "impoverished" SES.

[Mandrake]

Jensen's 1980 book Bias in Mental Testing seems to me to have a good index. But, unfortunately, it is not published on the web.
It is much better than The _g_ Factor.

If you at least own the physical book, you can use the Questia search function as an index to help you find things in the book.
That is a useful service, but one that I do not have. The approach I have taken has been to create my own index. It is labor intensive, but I find the extra work helps me to recall the contents.

[Mandrake]

From the excerpts there, it doesn't sound like the authors are saying environmental influences are lost at all. Instead, it seems to be suggesting a fairly reasonable argument that underlying genetic predisposition and environmental factors interact with one another to influence adolescent behavior.
I previously referenced this paper from Intelligence:
Genetics and Intelligence: What’s New?
ROBERT PLOMIN, STEPHEN A. PETRILL
Institute of Psychiatry, London

On page 12, it says:
Until recently, environmental factors that affect intelligence were thought to operate primarily in a shared manner. For example, our earlier review of genetic influences on intelligence concluded that shared environment accounted for about 25% of the variance of IQ scores. The strongest evidence for the importance of shared environment comes from the correlation for adoptive siblings, that is, pairs of genetically unrelated children adopted into the same adoptive families. As shown in Figure 2, adoptive siblings correlate about .30 for IQ, suggesting that about a third of the variance in IQ can be attributed to shared family environment. However, the studies reviewed in Figure 2 happened to assess adoptive siblings as children. In 1978, the first study of older adoptive siblings yielded a strikingly different result: The IQ correlation was -.03 for 84 pairs of adoptive siblings from 16 to 22 years of age (Scat-r & Weinberg, 1978). Other studies of older adoptive siblings have also found similarly low IQ correlations. The most com-pelling evidence comes from a lo-year follow-up study of 181 adoptive siblings. At the average age of 8 years, their IQ correlation was .26. However, 10 years later, their IQ correlation was - .Ol , suggesting that shared family environmental effects on IQ decline to negligible levels after adolescence (Loehlin, Horn, & Willerman, 1989) (see Figure 7).

We are confident that the question is when, not whether, genes will be found that are associated with intelligence. Indeed, many genes have already been found that are associated with low intelligence. More than 100 rare single-gene disor-ders include mental retardation among their symptoms (Walhsten, 1990).
The figure 7 is on page 13 and shows that the shared environment shows up in childhood, then vanishes completely.

[Mandrake]

This may be of interest to some of you:

Concordance rates of IQ scores

Evidence from family studies provides the main supporting evidence from which arguments about the relative roles of genetics and environment are constructed.

A large number of the study of twins reared apart was undertaken by Thomas Bouchard of the University of Minnesota starting in 1979. He “collected” pairs of separated twins from all over the world and reunited them while testing their personalities and IQs. Other studies at the same time concentrated on comparing the IQs of adopted people with those of their adopted parents and their biological parents or their siblings. Put all these studies together, which include the IQ tests of tens of thousands of individuals, and the table looks like this:

Same person tested twice 87%

Identical twins reared together 86%

Identical twins reared apart 76%

Fraternal twins reared together 55%

Biological siblings reared together 47% (studies show that reared apart about 24%)

Parents and children living together 40%

Parents and children living apart 31%

Adopted children living together 0%

Unrelated people living apart 0%


from
Ridley, M. (1999). Genome: The autobiography of a species in 23 chapters. London: Fourth Estate Ltd.

[hitssquad]

Let me add that one contributor to these discussions (screen name "hitsquad") is well informed and has posted comments that are identical to what I would have written about the same issues. This person has addressed the questions pertaining to intelligence with facts that are scientifically valid and known to those who have studied the subject in depth.Go for it (http://www.physicsforums.com/showthread.php?t=41166). I won't complain.

[nuenke]

From the excerpts there, it doesn't sound like the authors are saying environmental influences are lost at all. Instead, it seems to be suggesting a fairly reasonable argument that underlying genetic predisposition and environmental factors interact with one another to influence adolescent behavior.

The book looks at three causes for differences in intelligence and behaviors. Using a very large group, and using longitudinal studies, as well as including all of the relationships (twins, adopted children, families with half brothers/sisters, etc.), they determined that when young, the shared environment may be important, but as children grow older, it is almost exclusively genes and the non-shared environment that determines these factors. That is, the family environment has very little impact on children once they enter their teens - they find, produce and gravitate towards their own individual environments depending on their genes and other unknown factors. That is, no one really knows what the interaction is, but it is not the family that makes the person.

This is pretty much accepted by behavior geneticists. Also see the Nurture Assumption by Judith Rich Harris, 1998. She discovered this, if I remember right, because she edited a lot of research papers and noticed irregularities. Her book is a much easier read, and explains how children find their own niches.

Of course, this new research really hurts educators, psychologists, social workers, etc. There is a huge industry built upon naïve environmentalism, and they are not about to lose their livelihoods because new research has made many of their programs quite meaningless.

[Moonbear]

That is, the family environment has very little impact on children once they enter their teens - they find, produce and gravitate towards their own individual environments depending on their genes and other unknown factors. That is, no one really knows what the interaction is, but it is not the family that makes the person.

Can you please expand on this? Are they saying environment is not at all a factor, or that the social influences shift from family to some other source? Part of the social shift in adolescence is becoming independent of your parents and instead identifying more with same-aged peers.

Of course, this new research really hurts educators, psychologists, social workers, etc. There is a huge industry built upon naïve environmentalism, and they are not about to lose their livelihoods because new research has made many of their programs quite meaningless.

You mean those who would say it's ONLY social factors, and NEVER biological? Sure, any view that rigid isn't going to last long in any field of science.

Something that still doesn't seem clear to me is which definitions of environmental are being employed here. I suspect we may not all have the same idea in mind. When I think of environmental influences, I think of anything coming from outside our own body, including physical/chemical/biological external influences (including intrauterine environment of the fetus) as well as social influences from both family and other people (teachers, friends, neighbors). In a number of the posts here, I get the impression environmental is being used synonymously with social influences only, i.e., nature vs nurture. Conversely, I also keep getting the impression that some are considering anything that is not due to social influence must be due to genetic influence rather than other physical/biological factors, and I'm not sure where everyone is categorizing those factors. It is quite possible this is leading to a good deal of our misunderstandings in this thread because we aren't all thinking the same definitions.

In Plomin's 2004 article, he discusses that one of the reasons why it may be difficult to pinpoint a genetic link to IQ is that a single gene may only account for something as small as 1% of the variation, such that you can never detect a difference by looking for one gene at a time. So, for those who are willing to embrace the genetic linkage, and would accept Plomin as an authority on the subject, why could the same not be true of environmental factors? Often, we try to study single environmental factors to avoid the difficulty in interpreting findings with numerous variables. What if we can't detect any differences for a single environmental factor, such as SES, for the same reasons we can't detect significant differences related to a single gene? And if we did find a gene, we'd need to show that it then results in a functional protein that also differs in expression levels. And is that protein expression altered by environment? Or does it alter the way we respond to our environment? Or both, in a feedback loop? There is prior evidence that both can occur. In behavioral endocrinology, hormones influence behavior, but then behavior also influences hormone secretion. It's incredibly difficult to tease these two directions of interaction apart.

[hitssquad]

That is, the family environment has very little impact on children once they enter their teens - they find, produce and gravitate towards their own individual environments depending on their genes and other unknown factors. That is, no one really knows what the interaction is, but it is not the family that makes the person.Can you please expand on this? Are they saying environment is not at all a factor, or that the social influences shift from family to some other source?In regards to heritability, we consider phenotypic variance accountable for on the one hand by environemental variance and on the other hand by genetic variance. If a teen "gravitates toward" specific environments, genetics would be accounting for the variance in environment and hence ultimately accounting for variance in phenotype. What is proposed is not that the teens are shifting from the family to random outside influence, but to ouside influence that caters to the teens' biological programming, of which genetics accounts for the bulk of the variance.



Part of the social shift in adolescence is becoming independent of your parents and instead identifying more with same-aged peers.And what is proposed is that peer selection (among other selections by teens) is not random, but is largely a product of genetically-determined tendency. There is no accounting for taste, as they say, and it is proposed that variance in taste in environment may be more largely accountable for by variance in genetic code than by variance in environment.



Something that still doesn't seem clear to me is which definitions of environmental are being employed here.Heritability refers to variance in phenotypic outcome accountable for by genetics as opposed to accountable for by environment. Environment is all factors left over when genetic code is controlled for.



When I think of environmental influences, I think of anything coming from outside our own bodyThen you are mistaken, because in terms of heritability environment is any factor that is not genetic. That includes the body itself. For example, genetic code expresses throughout a person's life. But the state of the body has visible effects on genetic expression. When people reach physical maturity, their genes still express proteins that code for growth factors. Yet they do not grow any more. This is because of states in the body that prevent growth in the presence of growth factor. One of these states is the hardening of the ends of bones. If the ends of bones remained soft, as they are when we are children, growth factors might continue to stimulate bone growth indefinitely - and people would grow to towering heights throughout their lifetimes, as trees do.



In a number of the posts here, I get the impression environmental is being used synonymously with social influences only, i.e., nature vs nurture.Yes. This is a classic confusion of the term "environment." What normally happens in nature/nurture discussions is that the equivocation fallacy is committed in regards to the definition fo the term environment. One moment it means all environment (all variance not genetic), and the next moment it means only intellectual stimulation. Arthur Jensen suggested that when we discuss environmental variance we be clear about whether we are speaking in terms of biological variance; variance in intellectual stimulation; or all non-genetic cariance (all environmental variance).



In Plomin's 2004 article, he discusses that one of the reasons why it may be difficult to pinpoint a genetic link to IQ is that a single gene may only account for something as small as 1% of the variation, such that you can never detect a difference by looking for one gene at a time. So, for those who are willing to embrace the genetic linkage, and would accept Plomin as an authority on the subject, why could the same not be true of environmental factors?There is no environmental counterpart to the discrete gene. In regards to heritability, environment is taken as one big lump and genetics is taken as one big lump. It stands to reason that if it has been established that genetic variance accounts for any amount of variance in a given phenotypic trait that we should also be able to find variance in specific genes that accounts for the same phenotypic trait variance. But searching for genes is not directly a part of heritability studies. Heritability of g in various human populations has already been established by selectively controlling for variance in environment and by selectively controlling for variance in genetic code.



What if we can't detect any differences for a single environmental factor, such as SES, for the same reasons we can't detect significant differences related to a single gene?SES is not comparable to a discrete gene. You can silence a discrete gene, but you cannot silence SES. SES is an axis. A gene is quantum piece of code.



And if we did find a gene, we'd need to show that it then results in a functional protein that also differs in expression levels.No. The gene in question might be coding for the silencing or unsilencing of other parts of the genome. Discrete production of a protein by the IQ-related gene in question may not be necessary for that to occur.



And is that protein expression altered by environment?Of course it is affected by environment. Studies of heritability have nothing to do with teasing out discrete affectors. They simply control for variance of environment and genetics and see how that results in changes in variance of expression of one or more phenotypic traits.

[Moonbear]

Then you are mistaken, because in terms of heritability environment is any factor that is not genetic. That includes the body itself. For example, genetic code expresses throughout a person's life. But the state of the body has visible effects on genetic expression. When people reach physical maturity, their genes still express proteins that code for growth factors. Yet they do not grow any more. This is because of states in the body that prevent growth in the presence of growth factor. One of these states is the hardening of the ends of bones. If the ends of bones remained soft, as they are when we are children, growth factors might continue to stimulate bone growth indefinitely - and people would grow to towering heights throughout their lifetimes, as trees do.

I wouldn't have chosen the word mistaken. :grumpy: It appears to be a difference in terminology from my field in which environmental does mean anything from outside the body. This is why I asked, because it is becoming apparent that we aren't all talking about the same thing.

Yes. This is a classic confusion of the term "environment." What normally happens in nature/nurture discussions is that the equivocation fallacy is committed in regards to the definition fo the term environment. One moment it means all environment (all variance not genetic), and the next moment it means only intellectual stimulation. Arthur Jensen suggested that when we discuss environmental variance we be clear about whether we are speaking in terms of biological variance; variance in intellectual stimulation; or all non-genetic cariance (all environmental variance).

Well, at least that much we can agree on. :wink: We need to be explicit in our definition of environment, or, more importantly, various authors' definitions of environment, when discussing it here. I think this is leading to a lot of additional confusion in this discussion.

[Mandrake]

Of course, this new research really hurts educators, psychologists, social workers, etc. There is a huge industry built upon naïve environmentalism, and they are not about to lose their livelihoods because new research has made many of their programs quite meaningless.
Yes indeed! The political and job related motivations for promulgating false concepts concerning environmental factors is huge. It has resulted in massive spending without returns. We have an inverse relationship between school spending and educational results precisely because the spending has been narrowly focused on population groups that will not show cognitive improvements as a result of the programs advertised to produce gains. The politics of this issue are so robust that I doubt that the subject can be discussed openly in any educational or political forum. The special interest side will simply shout down the scientific findings and use their usual "dirty racist" name calling as their only weapon. This struggle is similar to the Christian church as it sought to stop the advancement of science.

[Mandrake]

Can you please expand on this? Are they saying environment is not at all a factor, or that the social influences shift from family to some other source?
There are shared and not-shared environmental factors. Family factors are the shared ones. I previously quoted from Plomin (this thread) that the shared factors vanish in adolescence. In childhood, the shared factor is about 25%. From there, it goes to zero.

Part of the social shift in adolescence is becoming independent of your parents and instead identifying more with same-aged peers.
More likely is that genetic expression increases.

When I think of environmental influences, I think of anything coming from outside our own body, including physical/chemical/biological external influences (including intrauterine environment of the fetus) as well as social influences from both family and other people (teachers, friends, neighbors).
Jensen divides environmental factors into macro and micro, where the macro environment is that which is due to social interactions (family, institutional, etc.) and the micro environment is due to chemical and biological elements. The micro environment includes the intrauterine environment. When you subtract the variance due to genetics (considering intelligence), the factors that remain are environment and error. Together they add to about20-30% of the total variance.

Obviously, adoption studies are important to the observation of the evaporation of the shared environmental component.

By adolescence (by which time parental influence is weak in the modern West), unrelated children who have grown up as adoptees in the same family show quite simply no similarity at all in their levels of g . As Neisser et al. (1995) conclude in their review for the American Psychological Association, "Severely deprived, neglectful or abusive environments must have negative effects on a great many aspects of development, including intelligence. Beyond that minimum, however, the role of family experience is now in serious dispute." [Brand, C. (1996). The _g_ Factor: General Intelligence and Its Implications. Chichester, England: Wiley]

In Plomin's 2004 article, he discusses that one of the reasons why it may be difficult to pinpoint a genetic link to IQ is that a single gene may only account for something as small as 1% of the variation, such that you can never detect a difference by looking for one gene at a time. So, for those who are willing to embrace the genetic linkage, and would accept Plomin as an authority on the subject, why could the same not be true of environmental factors?
It may well be true that environmental factors account for only 1% of the variance each. I don't see the problem. We know the sum of the genetic influence and we know the remainder is due to the sum of all environmental and error components.

Often, we try to study single environmental factors to avoid the difficulty in interpreting findings with numerous variables. What if we can't detect any differences for a single environmental factor, such as SES, for the same reasons we can't detect significant differences related to a single gene?
It is relatively unimportant to identify causes of 1% in variance when we can identify the sum. There is no dispute that the sum of all environmental factors is equal to 100% minus the variance in the genetic component, minus the variance due to error. The end finding is completely consistent with the findings of scores of careful research programs.

Jensen: "One commentator likened the latest phase of the nature-nurture IQ debate to "a stomping match between Godzilla [that is, genes] and Bambi [that is, environment]."
See page 100 Miele (2002) - Intelligence, Race, and Genetics: Conversations with Arthur R. Jensen

[Waterdog]

This may be of interest to some of you:

Concordance rates of IQ scores

Evidence from family studies provides the main supporting evidence from which arguments about the relative roles of genetics and environment are constructed.

A large number of the study of twins reared apart was undertaken by Thomas Bouchard of the University of Minnesota starting in 1979. He “collected” pairs of separated twins from all over the world and reunited them while testing their personalities and IQs. Other studies at the same time concentrated on comparing the IQs of adopted people with those of their adopted parents and their biological parents or their siblings. Put all these studies together, which include the IQ tests of tens of thousands of individuals, and the table looks like this:

Same person tested twice 87%

Identical twins reared together 86%

Identical twins reared apart 76%

Fraternal twins reared together 55%

Biological siblings reared together 47% (studies show that reared apart about 24%)

Parents and children living together 40%

Parents and children living apart 31%

Adopted children living together 0%

Unrelated people living apart 0%


from
Ridley, M. (1999). Genome: The autobiography of a species in 23 chapters. London: Fourth Estate Ltd.

The Minnesota Twins study really doesn't account for environment very well. The employ an inventory of items such as whether the households in which the separated twins are raised possess power tools or encyclopedias. Based on this they have argued that the environments of the twins in the study were heterogeneous. However, the twins are not from "all over the world," as you say. They come from a few culturally homogeneous countries such as the US, UK, Australia, West Germany, and a few others that are quite similar as well--both internally homogeneous and similar to each other. All of these countries provide basically the same opportunities for developing IQ and the same cultural emphasis on IQ-related tasks. In addition, the MN twin study's inventory of items that supposedly shows how heterogeneous the households are could be described as rather arbitrary or even silly. There is a reason that so-called "social science" is distinguished from "hard science" such as physics or chemistry--it's simply impossible to really control any variables in a social science.

No one would deny that MZ twins are more similar then unrelated strangers, but this would only come as news to the most radical environmentalists. For most reasonable people, who believe that variation of traits in a population is partly due to environment and partly to genetics, the MN twins study is really not that enlightening, since it only tells us what we already knew. The beanfield analogy is most apt here. They are studying beans in one field where soil, light, and water are all constant. Not surprising at all that in that case, beans with the same genes don't show much variation. They have not looked at how beans with identical genes would develop in fields with radically differing soil quality, sunlight, water, etc. In fact, the authors of the MN twins study explicitly state that their study of within-group variance cannot be used to draw any conclusions about between-group variance. This last point is usually ignored by the radical genetic determinist crowd who misuse their work.

[Mandrake]

The Minnesota Twins study really doesn't account for environment very well. The employ an inventory of items such as whether the households in which the separated twins are raised possess power tools or encyclopedias. Based on this they have argued that the environments of the twins in the study were heterogeneous. However, the twins are not from "all over the world," as you say.
Did I mention the Minnesota Twins study? Do you think this is the only twins study reported in the literature? Besides the Burt studies, which are sometimes not cited, there are four other studies that produced essentially identical results. All of these are for MZA's:

Newman et al.
Shields (1%2)
Juel-Nielsen
Minnesota Study

I just now did a search on "twin studies" within the Journal Intelligence. There were 21 hits. I looked at the first few. Each was from a different researsh team and each from a different country. The last one I checked studied just under 7,000 twin sets. Your attempt to refute my comment is incomprehensible. Do you really think that there has only been one twin study and that other nations have not studied twins? Perhaps that is not what you intended to imply? I hope not, but that is the implication I read into the comment.
They come from a few culturally homogeneous countries such as the US, UK, Australia, West Germany, and a few others that are quite similar as well--both internally homogeneous and similar to each other. All of these countries provide basically the same opportunities for developing IQ and the same cultural emphasis on IQ-related tasks.

We know from adoption studies, intensive intervention programs, and longitudinal studies that the shared environment vanishes by age 17. Have you seen real (as in peer reviewed) data showing that any macro environmental effect has ever caused a permanent boost in _g_? How about even a one year boost in _g_?

No one would deny that MZ twins are more similar then unrelated strangers, but this would only come as news to the most radical environmentalists.
MZ twins are more similar than any other category of humans.

[Waterdog]

Did I mention the Minnesota Twins study?

Yes, you did.


Do you think this is the only twins study reported in the literature?

No. However, it is the most commonly discussed by the semi-literati on internet discussion boards, and hence the most relevant to analysis.

Besides the Burt studies, which are sometimes not cited, there are four other studies that produced essentially identical results. All of these are for MZA's:

Newman et al.
Shields (1%2)
Juel-Nielsen
Minnesota Study



You seem to have three other studies there, not four. Perhaps you meant besides Burt?

I just now did a search on "twin studies" within the Journal Intelligence. There were 21 hits. I looked at the first few. Each was from a different researsh team and each from a different country. The last one I checked studied just under 7,000 twin sets.

No one suggested N was insufficient, did they? The question is where the subjects come from and where they are placed, not how many there are. So, what are the countries? How did the researchers try to control for environment? OK, I did the same search and noted Australia, Germany, the United Kingdom, etc. What does that have to do with the argument I made? Can you cite a study of pairs of twins who were raised in truly different environments, e.g., one set raised in Norway and their MZ twins raised in Ghana? That would tell us something. Else, you are simply stating the obvious: genetically identical organisms that develop in similar environments will be similar. Why is this finding noteworthy? Why do we need dozens of studies to demonstrate what is obvious?


Your attempt to refute my comment is incomprehensible.

Heh.


Do you really think that there has only been one twin study and that other nations have not studied twins? Perhaps that is not what you intended to imply? I hope not, but that is the implication I read into the comment.

Your statement here makes it obvious that you didn't understand what I wrote. The problem is that each pair of twins develops within a similar environment. Doesn't matter whether you have twins from different countries if the members of each pair have similar environments. Then you haven't controlled for environment, even if the environment does differ between different pairs.

We know from adoption studies, intensive intervention programs, and longitudinal studies that the shared environment vanishes by age 17. Have you seen real (as in peer reviewed) data showing that any macro environmental effect has ever caused a permanent boost in _g_? How about even a one year boost in _g_?

Ah, the fetish of the peer review. Do you know that many of the early behavioral geneticists, people who you now probably think of as great minds, couldn't get their stuff published because the peer reviewers for the major journals didn't like it? Peer review is a process whose goal is to produce high quality in publications, but it is far from perfect. Good articles get rejected and bad articles get accepted. Just because something is "peer reviewed" doesn't mean it's true.

As for boosting, "g," I doubt it's possible to raise someone's IQ test scores significantly once they reach school age. I would agree with you there. The most important environmental effects have to do with pre-natal care, followed by the development of the neural network in early childhood. Neuroscientists have documented (yes, in *peer reviewed* publications) that the brain develops its structure of neurons iin response to environmental stimuli. Since MZ twins tend to be placed in similar homes in the same countries, it is not surprising that they have similar IQ's as adults. They get the same nutrition and other environmental effects in the womb, that's for sure, and quite similar during the rest of early childhood. These are the crucial periods in neural development.

Anyway, no one would deny that there is a large genetic component. How could a biological organism develop with no reference to its own DNA? What I am arguing against is the idea that it has been "proven" that this is as high as .80. Environment has never been controlled for in any twin study, so this has not been proven at all. My guess is that, like bean sprouts, human brains with the same genes can develop in all sorts of different ways in response to different environmental stimuli.

MZ twins are more similar than any other category of humans.

Who ever said they weren't? Again, you clearly don't understand what I wrote.

More generally, here is a *peer reviewed* article critical of the use of twin studies in behavioral genetics. Now you are going to tell me that this article is wrong even though it's *peer reviewed*! lol.



Accession Number
Peer Reviewed Journal: 2003-01223-002.

Author
Ehrlich, Paul; Feldman, Marcus.

E-Mail Address
Feldman, Marcus: marc@charles.stanford.edu

Title
Genes and Cultures: What Creates Our Behavioral Phenome? [References].

Source
Current Anthropology. Vol 44(1) Feb 2003, 87-107.
Univ of Chicago Press, US

Abstract
(from the journal abstract) A central theme of the flood of literature in recent years in "evolutionary psychology" and "behavioral genetics" is that much or even most human behavior has been programmed into the human genome by natural selection. We show that this conclusion is without basis. Evolutionary psychology is a series of "just-so" stories rooted in part in the erroneous notion that human beings during the Pleistocene all lived in the same environment of evolutionary adaptation. Behavioral genetics is based on a confusion of the information contained in a technical statistic called "heritability" with the colloquial meaning of the term, exacerbated by oversimplification of statistical models for the behavioral similarity of twins. In fact, information from twin studies, cross-fostering, sexual behavior, and the Human Genome Project makes it abundantly clear that most interesting aspects of the human behavioral phenome are programmed into the brain by the environment. The general confusion created by the genetic determinists has had and will continue to have unfortunate effects on public policy. Commentaries on this article and a reply are appended. (PsycINFO Database Record (c) 2004 APA, all rights reserved)

[Mandrake]

Mandrake:
Do you think this is the only twins study reported in the literature?

No. However, it is the most commonly discussed by the semi-literati on internet discussion boards, and hence the most relevant to analysis.

Really? "Most relevant" is determined by "the semi-literati?" I didn't know that. Thank you.

You seem to have three other studies there, not four. Perhaps you meant besides Burt?
I wrote "Besides the Burt studies, ..."

Mandrake: I just now did a search on "twin studies" within the Journal Intelligence. There were 21 hits. I looked at the first few. Each was from a different research team and each from a different country. The last one I checked studied just under 7,000 twin sets.

No one suggested N was insufficient, did they?
Gee, I guess not. Thank you for adding that profound and helpful insight. I am sure that the other participants here appreciate it as well.

The question is where the subjects come from and where they are placed, not how many there are.
The question is the value of h^2. The MZA studies confirm other computations that show the value of h^2 to be between 0.70 and 0.80. The Texas Adoption Project data have been used to calculate h^2 via path analysis. The result was 0.78. MZA studies typically show about 0.75. Burt's studies showed 0.77.
[Miele - Intelligence, Race, and Genetics, P. 103]

So, what are the countries? How did the researchers try to control for environment?
The effects of family environment have been significantly different in some specific MZA pairs. Have you read the case studies? If so, you know that there are pairs from grossly different SES environments. But more importantly, the adoption studies include data sets in which children were reared in much different family environments than their biological peers. There are data sets for children adopted into different countries; to families of higher mean IQs and to families with lower mean IQs. There are also inter-racial adoption data. These studies are extensive, thoroughly reported in the literature, and all show that the family contribution to IQ in adulthood is essentially zero.

Can you cite a study of pairs of twins who were raised in truly different environments, e.g., one set raised in Norway and their MZ twins raised in Ghana? That would tell us something.
Please see my later comments on extreme environments. Looking at such large differences certainly allows for the introduction of micro environmental components, which are well known to account for all of the environmental component of the variance in adult intelligence.

There already exist good studies to account for large differences in the shared environment. The family environments in the Minnesota study were actually measured:
Sources of human psychological differences: the Minnesota study of twins reared apart
Thomas J. Bouchard Jr.; David T. Lykken; Matthew McGue; Nancy L. Segal; Auke Tellegen
Science, Oct 12, 1990 v250 n4978 p223(6)
A checklist of available household facilities (for example, power tools, sailboat, telescope, unabridged dictionary, and original artwork) provides an index of the cultural and intellectual resources in the adoptive home [17]. Each twin completes the Moos Family Environment Scale (FES), a widely used instrument with scales describing the individual's retrospective impression of treatment and rearing provided by the adoptive parents during childhood and adolescence [18]. The age- and sex-corrected placement coefficients for these and other measures are shown in Table 3, together with the correlations between twins' IQ and the environmental measure ([r.sub.ft]) and the total estimated contribution to MZA twin similarity. The maximum contribution to MZA trait correlations that could be explained by measured similarity of the adoptive rearing environments on a single variable is about 0.03(19). The absence of any significant effect due to SES or other environmental measures on the IQ scores of these adult adopted twins is consistent with the findings of other investigators [20]. Rearing SES effects on IQ in adoption studies have been found for young children but not in adult samples [21], suggesting that although parents may be able to affect their children's rate of cognitive skill acquisition, they may have relatively little influence on the ultimate level attained. [17.] M. McGue and T. J. Bouchard, Jr., in Advances in the Psychology of Human Intelligence, R. J. Sternberg, Ed. (Erlbaum, New York, 1989), vol. 5, p. 7. This checklist yields four relatively independent scales: scientific or technical, cultural, mechanical, and material possessions.

[18.] R. H. Moos and B. S. Moos, Manual: Family Environment Scale (Consulting Psychologists Press, Palo Alto, CA, 1986).
[19.] Formally, this is the maximum linear contribution; nonlinear effects are, of course, possible. For these data, however, investigation of higher-ordered relationships (quadratic and cubic) showed no associations that did not exist at the linear level, and there was no discernible nonlinearity detected in visual inspection of the scatterplots.
[20.] T. J. Bouchard, Jr., Intelligence 7, 175 (1983).
[21.] C. Capron and M. Duyme [Nature 340, 552 (1989)] have shown an SES effect in an adoption study of young children; S. Scarr and R. Weinberg [Amer. Sociol. Rev. 43, 674 (1978)] did not find an SES effect in a study of young adult adoptees.

Else, you are simply stating the obvious: genetically identical organisms that develop in similar environments will be similar. Why is this finding noteworthy? Why do we need dozens of studies to demonstrate what is obvious?
Some people have been of the opinion that family environments, institutional environments, and other macro environmental factors could be structured to boost intelligence. After the spending of many billions of dollars on such programs as Head Start, we now know that macro environmental factors are not present in adults.

I am curious as to your take on the conclusions drawn by such respected scientists and Bouchard and Lykken. One must assume that you believe that you have a superior vantage point and better understanding of the subject than the researchers who conducted the studies. Is that correct? How is it that you gained this superior insight? The findings of the Minnesota Twins study were not shocking, since they were in agreement with similar conclusions drawn a bit earlier and from different observations. For example, see: R. Plomin and D. Daniels, Behav. Brain Sci. 10, 1 (1987); L. J. Ea ves, H. J. Eysenck, N. G. Martin, Genes Culture and Personality: An Empirical Approach (Academic Press, New York, 1989).

Your statement here makes it obvious that you didn't understand what I wrote. The problem is that each pair of twins develops within a similar environment.
Your continued assertion to this effect is at odds with the research report I cited. I have not seen a claim that IQ cannot be lowered, even significantly so, by extremes in environment. The issue is largely unknown and is usually excluded by wording such as that used by Bouchard: "... this heritability estimate should not be extrapolated to the extremes of environmental disadvantage still encountered in society." He made that statement in recognition that, for example, his data set did not contain retarded subjects.

[Mandrake]

Waterdog: Doesn't matter whether you have twins from different countries if the members of each pair have similar environments. Then you haven't controlled for environment, even if the environment does differ between different pairs.
Your contention that the environments are "similar" is not universally true. There are significant differences in some of the pairs. One set of twins, Oskar Stohr of Germany and Jack Yufe of California were separated after their birth in Trinidad and grew up in very different cultural surroundings. Yufe was brought up a Jew by his Jewish father in Trinidad and Stohr was raised in occupied Czechoslovakia and went to a Nazi-run school.

Mandrake: We know from adoption studies, intensive intervention programs, and longitudinal studies that the shared environment vanishes by age 17. Have you seen real (as in peer reviewed) data showing that any macro environmental effect has ever caused a permanent boost in _g_? How about even a one year boost in _g_?

Waterdog: Ah, the fetish of the peer review. Do you know that many of the early behavioral geneticists, people who you now probably think of as great minds, couldn't get their stuff published because the peer reviewers for the major journals didn't like it? Peer review is a process whose goal is to produce high quality in publications, but it is far from perfect. Good articles get rejected and bad articles get accepted. Just because something is "peer reviewed" doesn't mean it's true.
Peer review is not a fetish, it is an important precaution that helps to weed out lunacy. When people discuss a topic in a forum, such as this one, there are a lot of assertions made and many claims are shown to be based on the opinions of journalists and people who have not established that they have any understanding of the subject at hand. Do you wish to argue that we are better served by material that is not peer reviewed? Peer review is not limited to the review by individual journals. In the case of psychometrics, there is peer review conducted on the Internet in a formal academic format. I have not argued that peer review inherently produces accuracy, but I do contend that it is a viable means of filtering noise.

As for boosting, "g," I doubt it's possible to raise someone's IQ test scores significantly once they reach school age. I would agree with you there.
Do you have any evidence that any macro environmental experience has been shown to boost intelligence in such a manner that the boost remains after the age of 17?

The most important environmental effects have to do with pre-natal care, followed by the development of the neural network in early childhood.
Agreed. This is well known and well documented. The intrauterine environment is totally a micro environmental factor. Essentially all of the non-genetic, non-error, parts of the variance in intelligence among adults is due to the micro environment.

They get the same nutrition and other environmental effects in the womb, that's for sure, and quite similar during the rest of early childhood. These are the crucial periods in neural development.
Jensen has commented that "most of what happens during pregnancy makes twins more different, rather than more alike, and thus causes us to underestimate the true heritability." [Miele (2002) - Intelligence, Race, and Genetics: Conversations with Arthur R. Jensen, P. 102]

Anyway, no one would deny that there is a large genetic component. How could a biological organism develop with no reference to its own DNA? What I am arguing against is the idea that it has been "proven" that this is as high as .80.
The various computations are in agreement. Path analysis and MZA data show the same results from many data sets. Heritability can be determined by the analysis of inbreeding depression and by vairous othe methods. The numbers are consistent enough that the burden of proof must lie on the person who says they are wrong.

[Nereid]

There are no elite competitive athletes that I am aware of who do not use performance-enhancing drugs. Most performance-enhancing drugs are not barred by sports bodies.so what is all the fuss about re the Olympics and drugs? IIRC, there is a whole new bureaucracy devoted to testing athletes for 'banned substances' (aka 'performance enhancing drugs'), and fierce denials from those who win (e.g. that US Tour de France winner)Caffeine is such a drug (motor time enhancing and also peak explosive strength enhancing and athletic endurance enhancing), and it is interesting enough that virtually all athletes use it to enhance performance.But didn't I read that an Olympic athlete was stripped of his medal precisely because he tested too high on caffeine? (His excuse was that he was a caffeine addict, typically drinking 10 cups a day)
No. g tends to decline commensurately with decline of physical parameters. Some people age more slowly than others. This seems to be largely mediated by their body's relative production levels of antioxidants such as SOD and uric acid.

People can radically increase their rates of mental decline by abusing alcohol and other drugs and exposing themselves to biologically damaging levels of various chemicals. Lack of micronutrient intake, relative to that of same-age peers, will also increase rate of mental decline, as will lack of food-based antioxident (flavonoids, polyphenolics) intake, again relative to that of same-age peers.

Some adults have managed to virtually halt, relative to that of same-age peers, both their mental and physical age-related decline. These persons have adopted comprehensive anti-senescence regimens. Many of these persons refer to themselves as life extensionists (http://groups.google.com/groups?group=sci.life-extension).very interesting! Thanks hitssquad.Persons with lower IQs to begin with tend to be relatively incompetent at preserving their own health. Thus, the present author would expect that persons with lower IQs to begin with would also suffer greater age-related declines in IQ relative to those of same-age peers. See the recent paper (http://www.google.com/search?q=Gottfredson+health+iq) by Gottfredson on IQ and relative hygiene competency.so presumably a goal of an enlightened public health policy might be to retard this decline, much as (for example) public health policy might be directed to encouraging exercise, healthy diets, quitting smoking, etc?Females are known to age more slowly than men, physically. Based on that, I would expect that female cognitive decline is generally also retarded.What data is there to show, for example, that females or a certain (relatively advanced) age are more intelligent than males (who are otherwise equal)?Age-related hormone decline is known to dramatically affect cognitive parameters. Hormone replacement therapy is known to have an opposite dramatic effect (http://www.lef.org/protocols/prtcl-003.shtml) on cognitive recovery in older persons. This effect is mainly attributed to myelination, which is known to be largely mediated by the so-called "sex hormones".to what extent has this been nailed down to _g_? How does the 'sex hormone'/'myelination' relationship work? To what extent has it been validated by neuroscientists? How does it affect males vs females?There has never been a single documented case of any human reaching the age of 70 in good cognitive health. Before the recent life extension revolution, cognitive decimation on the order of several standard deviations was the norm for 70-year-olds. Persons who are relatively, compared with same-age peers, physically and mentally healthy in their senior years are relatively, compared with same-age peers, physically and mentally healthy in their senior years. Maybe you wanted to know if they were also relatively healthier than average when they were younger. Answer: generally, they were.This seems to suggest there is some kind of relationship between general health and _g_, specifically between physical health and _g_, at least in adults. How does this relate to Jensen's findings that _g_ in adults is largely hereditary?

[Nereid]

That seems to be the implication of the latest information. We are at the beginning, not the end, of the resolution of how and where the brain processes thoughts.Then equally claims which go beyond the very tentative first steps must be taken with a great many grains of salt (Rushton's spring to mind here).Lynn has convincingly demonstrated that the mean IQ for women is 4 points below the mean for men. This difference is entirely due to group factors and as such does not conflict with Jensen's frequently reported finding that there is no difference in the mean _g_ for men and women. The primary group factors at work are presumably spatial and quantitative.Can you say more please? What are 'group factors'? Which groups did Lynn test? When? How did he control for all the variables that we have so far uncovered?

On the face of it, Lynn's finding is in direct contradiction to hitssquad's earlier post.Evolutionary adaptations are going to be driven by advantages in the existing environment that contribute to increased probability that the holders of the genetic allele will survive to reproduce and that their children will do the same. If the existing climate does not contribute to that result, why would you expect an adaptation? Lynn has argued that it was extreme climate that caused increased spatial performance in Mongoloids (contributing to a slight IQ advantage relative to Caucasoids). He also speculated that this spatial advantage may have come at the price of decreased verbal abilities (both differences are measurable).Interesting. What time periods are we talking of here? what (historical) geographical regions? Why would one not expect (say) the Saami to have the same adaptations? or the native Americans and Indians who lived at extreme altitudes?At present, the evidence points to IQ contributions in various parts of the brain, not just the prefrontal cortex. There was a strong hint of this in earlier research. That research involved the destruction of 48 locations of rat brains (there were meticulous control groups, pairs, etc.), followed by measurements of _G_ (upper case is used to designate the general factor in animals). The total findings are quite revealing and are reported on page 165 of The _g_ Factor. I am uninclined to type the whole result. Part: "Probably the most important finding is the very high correlation between the various tasks' _G_ loading and the number of brain structures that are significantly involved in the task performance -- a rank-order correlation of _.91."So psychometricians have made significant and original advances in mammalian biology too? Do you have papers from mammalian biologists (or neuroscientists) commenting on these contributions?Heavily loaded task = 17 brain structures
Simple task + 4 brain structures

"The _G_ factor correlated -.45 with the presence of _any_ brain lesion."

Britt Anderson determined that the _G_ factor scores for rats correlates with brain weight (they killed the unfortunate rodents) at r= +.48.

The subject of brain size has drawn a great deal of research attention for a very long time. I searched the INTELLIGENCE database and found 21 hits on "brain size." Some of the papers are very interesting, but way to long to discuss as part of this post. Since anyone seriously interested in psychometrics will have (and will have read) a copy of The _g_ Factor, they can review Jensen's comments through the entire chapter titled "Causal Hypothesis." Jensen goes through the math on page 442 to show that measurement data suggest that about 6 points of the W-B IQ gap are due to differences in brain volume. In comparing Negroid, Caucasoid, and Mongoloid means, he says "The regression of median IQ on mean cranial capacity is almost perfectly linear, with a Pearson r= +.998." After giving reasons, he goes on to say "Thus it appears that the central tendency of IQ for different populations is quite accurately predicted by the central tendency of each population's cranial capacity."Can you confirm please that Jensen's research was done entirely with US subjects, within a narrow time period? Also, how do the regresssions look when broken into gender and age cohorts?The same chapter includes a through discussion of the male-female difference.And Jensen's conclusions are at odds with Lynn's?

[Nereid]

I assume you understand that Cattell's example was intended to be understood as a statistical and not an anecdotal observation. When Cattell stated "The strong genetic component in criminality has already been proven up to the hilt," he was not implying that he had based that conclusion on a single observation, nor even on a set of personal observations. He was telling us that the subject has been reported in many sources and that the results are in agreement. Likewise, your family example, while interesting, is anecdotal.In which countries did Cattell do his research?The relationship of crime to IQ is also interesting. Cattell was not commenting on this, but it is discussed in The Bell Curve, in the chapter titled "Crime." [chapter 11] The discussion points out that criminal behavior correlates negatively with IQ. It should be noted that the content of chapters 1-12 in The Bell Curve are based entirely on a single population group (non-Latino whites).Presumably this is based entirely upon US data.The heritability of intelligence can be firmly established without examining ANY gifted individuals. Intelligence is heritable at all IQ levels. The mechanism for describing the heritability of intelligence is to find the mean for the parents and to locate the regression point between that mean and the population group mean. That point then becomes the mean value for the normal distribution that applies to the children of the parents in question.Unless you have oversimplified, or I have misunderstood, all this establishes is a relationship between parents and children; it doesn't begin to disentangle the many, many factors involved - genes, fetal environment, infant's and childhood experiences, ...This field of study is particularly associated with researcher Robert Plomin, who discovered IGF2R on chromosome 6. Whether or not the specific genes have been identified, heritability of a trait can be established. The concept of heredity was known long before genetic research identified any trait specific genes.One would have thought that something as overwhelmingly clear as the claimed _g_/hereditability relationship would have been very easily identified, at least in terms of *some* genes.As for the heritability of intelligence, it is quantified by path analysis and by MZA studies. The data typically fall around h^2 = 72% for young adults, increasing to 80% for old adults. [These are variances, not r values.] Inbreeding depression studies show that intelligence behaves similarly to other traits that are depressed by inbreeding. The only explanation for this is a genetic cause. This one observation is so strong that it cannot be refuted by any amount of hand waving.In which countries has this research been done? With what groups of subjects? What were the age and gender relationships (we have already seen that 'mental faculties', and IQ, decline at quite different rates for different people, with clear gender effects)? How did the researchers define 'young adult' and 'old adult'?The other part of h^2 is the environmental component. This component has been studied in great detail for decades, including the conduct of costly and lengthy experiments. Adoption studies (including interracial ones) have shown that adopted children initially show some correlation to the mean IQs of their adoptive parents, but that this vanishes by late adolescence. As adults they resemble the IQs of their biological parents to approximately the same extent as do children who were reared by their biological parents. Adopted children have a tiny negative correlation to their adoptive siblings.In which countries were these studies done? How did the researchers establish the 'race' of the subjects? How did they determine 'late adolescence'? How did the results vary with the age at which the children left the familial home? How did the adopted children differ from biological one in terms of the birth order _g_ effects?Intervention programs have attempted to alter the environmental component, but they have demonstrated that such efforts are doomed to failure. The final conclusion is obvious. Intelligence is determined genetically.[quote]In which countries were such intervention programs run? What interventions were attempted? How were the effectiveness of the interventions determined (not the outcome, but whether the intervention was, in fact, what the researchers thought)?[quote]I don't think your comment is accurate. You have made an assertion, but it is in disagreement with reality. Although some genes do not express themselves immediately, there is a strong early indication of the correlation between IQ and performance.
The _g_ Factor: General Intelligence and Its Implications:
"IQ rises in predictive value relative to other measures as years go on" (p.77). In a long-term follow-up of a random sample of state-school five-year-olds on the Isle of Wight, IQ correlated strongly (at .50) with children's later educational attainments, when they were fifteen. Such prediction for individuals across ten supposedly formative years is unparalleled in social science."How do these 'unparalleled' predictions compare with the decades long work of non-intelligence psychometricians? Is the *only* result of this clarity, from the whole of psychology, that of _g_ and hereditability?

[Nereid]

If 'matrix relations' tests have a _g_ loading of 0.94, what else is there is in these tests? In well constructed matrix relations tests, what is the typical individual variance (i.e. an individual takes the same (type of) test many times)?This questions seems so far to have gone unanswered, so I'm posting it again.

[Nereid]

Related to the discussion of children, as having a different envrionmental component to the phenotype:

Genetics and intelligence: What's new?
Intelligence, Volume 24, Issue 1, January-February 1997, Pages 53-77
Robert Plomin and Stephen A. Petrill

In this paper, the shared environment variance is given as 25% in childhood and zero after adloscence.To what extent do the researchers control for 'adolescence' (presumably related to hormones and physical growth) vs 'leaving the family' (going to live in a college dorm, getting married and moving out, gettin a job far from home, joining the army, whatever)? In which countries were these studies done?

[Nereid]

Intelligence appears to have at least some negative correlation with parity.How much (range)? How extensively has this been tested?I don't know. It is something that I have seen mentioned in various books and papers as part of the discussion of within family variance. Unfortunately, Jensen's books are rather poorly indexed (unlike The Bell Curve) so it is always difficult to find material in them.

Miller says that the levels of testosterone that children are exposed to may be related to parity. Presumably he meant the intrauterine environment.

Searching my files didn't work. The problems involve multiple meanings of the term "parity" and the difficulty in removing "disparity" from the search.This is another of my questions that hasn't yet been answered (so I'm repeating it).

[Nereid]

I am a physicist with a strong interest in psychometrics. I know the people who deal with intelligence, but that's it. I am familiar with the Myers-Briggs test you listed, but it only relates to intelligence in that intelligent people tend to have a profile that is not common in the general population (INTJ). Adding INTJ and INTP, accounts for 75% of the Mensa level population (per Mensa's report).OK. So, my understand is that:
- there is a field of scientific research called psychology
- within this, there is a discipline which uses quantitative methods to measure aspects of humans' brain capabilities (in the sense of using them, not in the sense of numbers of nerves, for example); it's called psychometrics
- within psychometrics, there is a sub-discipline called 'intelligence studies', and at least one other, to do with all other aspects of measurable brain capabilities.

Presumably, the two sub-disciplines have a strong common approach (after all, they study essentially the same thing).

So, what are the results of studies done on other (non-intelligence) psychometric variables (e.g. DISC?) and their relationship to intelligence?

What non-intelligence psychometric variables have been demonstrated to have as strong a hereditability as _g_? What 'environmental' variables have been shown to have important relationships with non-intelligence psychometric variables?

[Nereid]

In regards to heritability, we consider phenotypic variance accountable for on the one hand by environemental variance and on the other hand by genetic variance. If a teen "gravitates toward" specific environments, genetics would be accounting for the variance in environment and hence ultimately accounting for variance in phenotype. What is proposed is not that the teens are shifting from the family to random outside influence, but to ouside influence that caters to the teens' biological programming, of which genetics accounts for the bulk of the variance.



And what is proposed is that peer selection (among other selections by teens) is not random, but is largely a product of genetically-determined tendency. There is no accounting for taste, as they say, and it is proposed that variance in taste in environment may be more largely accountable for by variance in genetic code than by variance in environment.



Heritability refers to variance in phenotypic outcome accountable for by genetics as opposed to accountable for by environment. Environment is all factors left over when genetic code is controlled for.



Then you are mistaken, because in terms of heritability environment is any factor that is not genetic. That includes the body itself. For example, genetic code expresses throughout a person's life. But the state of the body has visible effects on genetic expression. When people reach physical maturity, their genes still express proteins that code for growth factors. Yet they do not grow any more. This is because of states in the body that prevent growth in the presence of growth factor. One of these states is the hardening of the ends of bones. If the ends of bones remained soft, as they are when we are children, growth factors might continue to stimulate bone growth indefinitely - and people would grow to towering heights throughout their lifetimes, as trees do.



Yes. This is a classic confusion of the term "environment." What normally happens in nature/nurture discussions is that the equivocation fallacy is committed in regards to the definition fo the term environment. One moment it means all environment (all variance not genetic), and the next moment it means only intellectual stimulation. Arthur Jensen suggested that when we discuss environmental variance we be clear about whether we are speaking in terms of biological variance; variance in intellectual stimulation; or all non-genetic cariance (all environmental variance).



There is no environmental counterpart to the discrete gene. In regards to heritability, environment is taken as one big lump and genetics is taken as one big lump. It stands to reason that if it has been established that genetic variance accounts for any amount of variance in a given phenotypic trait that we should also be able to find variance in specific genes that accounts for the same phenotypic trait variance. But searching for genes is not directly a part of heritability studies. Heritability of g in various human populations has already been established by selectively controlling for variance in environment and by selectively controlling for variance in genetic code.



SES is not comparable to a discrete gene. You can silence a discrete gene, but you cannot silence SES. SES is an axis. A gene is quantum piece of code.



No. The gene in question might be coding for the silencing or unsilencing of other parts of the genome. Discrete production of a protein by the IQ-related gene in question may not be necessary for that to occur.



Of course it is affected by environment. Studies of heritability have nothing to do with teasing out discrete affectors. They simply control for variance of environment and genetics and see how that results in changes in variance of expression of one or more phenotypic traits.So here comes a biological question from a non-biologist, perhaps somewhat on a par with a physics question from a non-physicist ... a gene is what the gene is; however, the extent to which it does its thing ('is expressed'?) is partly determined by its environment - it may be 'switched on', or not; its expression may be modified by other genes being switched on or not. The triggers may be all but inevitable (e.g. pregnancy, ubiquitous chemicals), or rare or entirely absent (e.g. certain autoimmune conditions?). Tracing something to a gene (or genes) in the former case should be, in principle, fairly straight-forward; but how could you tell the latter from a non-genetic effect?

[Tigers2B1]

In relation to personality types (discussed above) it's my understanding that in similar situations, introverts take in more information about their environment than extroverts. So – when both pertsonality types visit a wild party, the introvert tends to become overwhelmed /exhausted with this over-stimulation before extroverts – who may even tend to be energized.

On the other extreme, extroverts will have a much more difficult time enjoying what an introvert would consider a pleasant level of stimulation. A night of star gazing, for example, might drive an extrovert into fits of head banging just to create the extra stimulation needed to make him or her feel that "something is going on." As such, each personality type selects different areas of interest – especially when they are old enough to choose those interests for themselves (i.e., when they leave the family environment and enter that unique environment they create for themselves based, in part, on their differing brands of personality.)

[Mandrake]

Then equally claims which go beyond the very tentative first steps must be taken with a great many grains of salt (Rushton's spring to mind here).
There is obviously a lot of study ahead. The following paper specifically addresses the sex differences:
Sex Differences in Brain Gray and White Matter in Healthy Young Adults: Correlations with Cognitive Performance
Ruben C. Gur, Bruce I. Turetsky, Mie Matsui, Michelle Yan, Warren Bilker, Paul Hughett, and Raquel E. Gur
The Journal of Neuroscience, May 15, 1999, 19(10):4065–4072

The paper shows significant brain volumetric differences between the sexes:
Females have greater GM volume; Males have greater WM and CSF volumes (see figures 2 and 3)

M: Lynn has convincingly demonstrated that the mean IQ for women is 4 points below the mean for men. This difference is entirely due to group factors and as such does not conflict with Jensen's frequently reported finding that there is no difference in the mean _g_ for men and women. The primary group factors at work are presumably spatial and quantitative.

Can you say more please? What are 'group factors'?
The hierarchial factor analysis (as developed by Charles Spearman) of test items determines correlations between test items. Subsequent extractions determine those groups that are correlated and from those the _g_ factor can be extracted. In most tests, _g_ is the third order factor. The second order factors are often called "group factors." The precise group factors that emerge (there are only 7 or 8) are dependent on the design of the test. If a test is designed so that it does not contain test items that call upon a specific group factor, it will not be seen. Most standard IQ tests cover the full range of group factors.

It seems to me that a for someone to have a realistic understanding of _g_, he must invest enough study in factor analysis that he can understand that process. Word descriptions of _g_ inevitably mislead.

Which groups did Lynn test? When? How did he control for all the variables that we have so far uncovered?

The following paper addresses his ideas thoroughly:
Sex Differences in Intelligence and Brain Size:A Developmental Theory
Richard Lynn INTELLIGENCE 27(1): 1-12

I will quote some material from it and take up the remainder of your comments in a separate message.

From the age of 16 years onwards, the growth rate of girls decelerates relative to that of boys. The effect of this is that a discernible male advantage of about 4 IQ points develops from the age of 16 into adulthood, consistent with the larger average male brain size.

Fitting American data for adults to the model, it was proposed that males have higher mean IQs than females of 1.7 IQ points for verbal comprehension, 2.1 IQ points for reasoning (the average of 1.8 for verbal reasoning and 2.4 for non-verbal reasoning) and 7.5 IQ points for spatial ability. These scores can be averaged to a 3.8 IQ point male advantage for general intelligence, which can be rounded to 4 IQ points. Similar data were presented for Britain, Norway, Sweden, Indonesia and Northern Ireland, all of which showed a male advantage of similar magnitude. In addition, six data sets of the Wechsler adult intelligence test were assembled, four of which were from the US and one each from The Netherlands and China, in all of which males obtained higher mean full scale IQs than females ranging between 1 and 5 IQ points and averaging 3.1 IQ points. The Wechsler full scale IQ is proposed as an approximate alternative measure of general intelligence defined as the sum of verbal comprehension, reasoning and spatial abilities. Thus, we have in all 12 data sets all showing higher mean IQs in males among adults.

Packenberg and Gundersen (1997) compared 62 male and 32 female brains and estimated the numbers of neurons in the entire cerebral cortex. They report that the average male brain contained 22.8 billion neurons and the average female brain 19.3 billion, a statistically significant difference, but there was no sex difference in neuronal density. The average number of female neurons in this study is 85% that of males. This is almost identical to the sex difference in cranial capacity estimated by Rushton (1992), in which average female cranial capacity is 86% of that of males. From this, we can conclude that estimates of male and female cranial capacity provide an accurate estimate of the numbers of neurons in the average male and female brain.

... males do have higher mean IQs than females by approximately 4 IQ points, commensurate with their larger average brain size. This conclusion holds whether general intelligence is defined as the sum of the verbal comprehension, reasoning and spatial group factors (Lynn), as fluid intelligence or reasoning ability (Mackintosh, Jensen), or as Spearman's g measured from the first principal component or as the global IQ obtained from standard intelligence and aptitude tests (Jensen), so long as these fulfil the conditions stipulated by Jensen.

[Mandrake]

M: Evolutionary adaptations are going to be driven by advantages in the existing environment that contribute to increased probability that the holders of the genetic allele will survive to reproduce and that their children will do the same. If the existing climate does not contribute to that result, why would you expect an adaptation? Lynn has argued that it was extreme climate that caused increased spatial performance in Mongoloids (contributing to a slight IQ advantage relative to Caucasoids). He also speculated that this spatial advantage may have come at the price of decreased verbal abilities (both differences are measurable).

N: Interesting. What time periods are we talking of here?
The Ice Age. He argues that Mongoloids were geographically isolated by terrain and effectively held captive in an extreme environment that allowed only the most able to survive. The primary survival skill was hunting, which he argues calls upon spatial abilities. He speculated that the Mongoloid brain (at least for males) may have extended its function in the spatial area to such an extent that it traded off verbal abilities.

what (historical) geographical regions?
North of the Himalayas and east of the Urals. See his paper: The Intelligence of the Mongoloids: A Psychometric, Evolutionary and Neurological Theory. Personality and Individual Differences, 1987, 8, 813-844.

Why would one not expect (say) the Saami to have the same adaptations? or the native Americans and Indians who lived at extreme altitudes?
I am unfamiliar with the isolation and climatic stresses on these groups.

Quote:
At present, the evidence points to IQ contributions in various parts of the brain, not just the prefrontal cortex. There was a strong hint of this in earlier research. That research involved the destructin of 48 locations of rat brains (there were meticulous control groups, pairs, etc.), followed by measurements of _G_ (upper case is used to designate the general factor in animals). The total findings are quite revealing and are reported on page 165 of The _g_ Factor. I am not inclined to type the whole result. Part: "Probably the most important finding is the very high correlation between the various tasks' _G_ loading and the number of brain structures that are significantly involved in the task performance -- a rank-order correlation of _.91."

So psychometricians have made significant and original advances in mammalian biology too? Do you have papers from mammalian biologists (or neuroscientists) commenting on these contributions?
I have limited interest in this area. You can find appropriate discussions here:
Anderson, B. 1993. Evidence from the rat for a general factor that underlies cognitive performance and that relates to brain size: Intelligence? Neuroscience Letters, 153, 98-102.
Crinella, F. and Yu, J. 1995. Brain mechanisms in problem solving and intelligence: A replication and extension. Intelligence, 21, 225-246.

M: In comparing Negroid, Caucasoid, and Mongoloid means, he says "The regression of median IQ on mean cranial capacity is almost perfectly linear, with a Pearson r= +.998." After giving reasons, he goes on to say "Thus it appears that the central tendency of IQ for different populations is quite accurately predicted by the central tendency of each population's cranial capacity."

N: Can you confirm please that Jensen's research was done entirely with US subjects, within a narrow time period?
The _g_ Factor is a textbook, not a research paper. Jensen presents data from many sources. The name index, for example, is 8 pages long. The material in question was drawn from multiple studies, which are all referenced as you would expect in a scientific book. It is a bit tedious for me to compile all of the references. If this subject is of interest to you, I strongly recommend obtaining a copy of this book. It is the present standard reference.

Also, how do the regresssions look when broken into gender and age cohorts?

The references I gave you for Lynn contain sex differences in brain volumes and in the contents of those volumes. As I recall, he also addresses age. There is a developmental rate difference that appears between the sexes. Salthouse has written a lot on the subject. One paper that I recently read: Structural models of the relations between age and measures of cognitive functioning Timothy A. Salthouse. Intelligence 29 (2001) 93-115

The same chapter includes a through discussion of the male-female difference.And Jensen's conclusions are at odds with Lynn's?

Lynn disagrees with some of the explanations offered by Jensen. Those are discussed in great detail in the paper I previously referenced. Lynn has also documented the difference in knowledge between the sexes:

Sex differences in general knowledge
Richard Lynn, Paul Irwing, Thomas Cammock
Intelligence 30 (2001) 27–39

The study has four principal points of interest. First, it confirms the results obtained in the Wechsler standardisation samples shown in Table 1 that males tend to have more general knowledge than females. The magnitude of the male advantage as expressed in the sex difference on the general factor amounts to 0.51d or approximately half a standard deviation. This is a rather considerable advantage.

... the results of the sex differences on the six domains of general knowledge confirm the view that the differences between males and females in information are substantially determined by their different interests. Males have greater knowledge than females in Current Affairs (0.82d), Physical Health and Recreation (0.75d), Science (0.58d), and Arts (0.31d), but females have substantially greater knowledge than males in Family (
0.46d), while there is no sex difference in Fashion (
0.01d). These variations should probably be regarded as functions of different interests typically possessed by males and females. Considered in terms of the evolutionary psychology theory of sex differences presented by Geary (1998), these sex differences in interests are likely to be biologically programmed.

[hitssquad]

If 'matrix relations' tests have a _g_ loading of 0.94, what else is there is in these tests?A very few nonverbal, nonspatial visualization, and nonnumerical tests (such as Raven's Progressive Matrices and Cattell's Culture-Fair Test of g), which are based entirely on figural materials, have been expressly devised to maximize relation eduction and to minimize group factors. When factor analyzed among a wide variety of other tests, they do, in fact, have among the highest g loadings, and they usually have nonsignificant loadings on any less general factors. The Raven Matrices is sometimes moderately loaded on a broad spatial group factor, but always far less than on the g factor. Also, the Raven has some specificity (5 to 10 percent) arising most probably from the matrix format of all its items. Cattell's test largely "averages out" such specifics by including a variety of figural item types....


It is important to note that not every test of figural material involves the spatial ability factor. Raven's Progressive Matrices, for example, does not qualify as a spatial test. This is shown by the fact that when the Raven is factor-analyzed among a variety of tests including several tests that define a spatial factor, it does not significantly load on the spatial factor. The defining characteristic for spatial problems is that, in order to obtain the correct solution, the subject must visualize and manipulate the figural material mentally as if it were an object in three-dimensional space.(Arthur Jensen. The g Factor (http://www.questia.com/PM.qst?a=o&d=24373975). pp90, 534.)



In well constructed matrix relations tests, what is the typical individual variance (i.e. an individual takes the same (type of) test many times)?In psychometrics this is termed the test-retest reliability....



TEST- RETEST CHANGE IN SCORES

When the same test, or an equivalent or parallel form of the test, is administered to persons on two separate occasions, days, weeks, or even months apart, there is usually an increase in scores, called a "practice effect." It affects performance on the particular test and on highly similar tests. [4] Subsequent retesting on the same (or similar) tests, however, shows ever smaller gains. Typically the initial gain amounts to almost one-third of a standard deviation (about three to six points on the IQ scale).

The increment in scores due to the practice effect, however, has little effect on the rank order of individuals' scores. For intervals of less than one year, the test-retest correlations are generally above .90. This indicates that the test measures essentially the same factors on both occasions, despite the average increment in scores....

The higher a test's g loading, the less susceptible it is to a practice effect....

The inverse relationship between g loadings and practice effects, and the relative absence of g in the increments themselves, may explain the low external validity of the IQ gains that result from specific training in the various cognitive skills assumed to be measured by IQ tests. The training-induced gains in IQ scores fail to predict external criteria (e.g., scholastic achievement) to the degree that would be expected if the induced gain in IQ represented a true gain in g, rather than merely a gain in the test's specificity. This "hollow IQ" phenomenon is discussed more fully in a later section on the attempts to raise IQ by special educational interventions.
(Arthur Jensen. The g Factor (http://www.questia.com/PM.qst?a=o&d=24373936). pp51, 314-316.)



Regarding in particular the test-retest reliability of the various iterations of the Raven's Matrices, these (http://www.google.com/search?q=raven+matrices+test+retest+reliability) Google hits seem to provide some answers:

...In terms of its psychometrics, Raven's Progressive Matrices: has good test-retest
reliability between .70 and .90 ....

...Test-retest (http://www.le.ac.uk/pc/jm148/IntellLecture3.html) reliability –children: one week: .85, eleven years: .46 ....

...Test-retest (http://www.cps.nova.edu/~cpphelp/RSPM.html) correlations range from a low of .46 for an eleven-year interval to a high of .97 for a two-day interval. The median test-retest value is approximately .82. Coefficients close to this median value have been obtained with time intervals of a week to several weeks, with longer intervals associated with smaller values. Raven provided test-retest coefficients for several age groups: .88 (13 yrs. plus), .93 (under 30 yrs.), .88 (30-39 yrs.), .87 (40-49 yrs.), .83 (50 yrs. and over).

[Mandrake]

Unless you have oversimplified, or I have misunderstood, all this establishes is a relationship between parents and children; it doesn't begin to disentangle the many, many factors involved - genes, fetal environment, infant's and childhood experiences, ...
The heritability of intelligence can be determined without knowing every detail of the mechanism. We do not, for example, know how many genes are involved. The fetal environment is not listed as part of the genotype in the material I have read. Childhood experiences consist of micro and macro types. It is the micro environment that appears to contribute somewhat to the variance in adult intelligence.

In which countries has this research been done? With what groups of subjects? What were the age and gender relationships (we have already seen that 'mental faculties', and IQ, decline at quite different rates for different people, with clear gender effects)?
These are all good questions and are obviously of great concern to you, as I can tell by the fact that you have repeated the same questions dozens of times. I am afraid that my personal time limitations are such that it is not practical for me to continue to quote specific answers to such questions. In virtually every case, you can find the answer yourself by using a good Internet search engine. If I attempt to answer from memory, I will ultimately make errors, so I suggest that you simply make an effort to locate the appropriate material and read it.

How did the researchers define 'young adult' and 'old adult'?
The effect of shared environment is usually believed to be gone by age 17. The term young adult may vary by a few years, depending on the author, but should be taken to start around 17-25. The progression of increased heritability goes on throughout life. "Old," obviously refers to people who are several decades beyond "young." Such specifics are virtually always included in the research papers. I am simply not going to continue to verify them because I don't have the time.

In which countries were these studies done? How did the researchers establish the 'race' of the subjects? How did they determine 'late adolescence'? How did the results vary with the age at which the children left the familial home? How did the adopted children differ from biological one in terms of the birth order _g_ effects?
There are numerous studies in the literature. The best way to answer these questions is to locate and read some of the material, or to read The _g_ Factor. As you know, biological studies involve multiple variables. Researchers make an effort to control for the effects that are likely to cause distortions of the effect being studied. It is common practice to discuss such controls at length. When prior investigations have shown that particular variables are second or third order effects, they may be considered to be inconsequential enough that the variable under study can still be investigated adequately.

In which countries were such intervention programs run? What interventions were attempted? How were the effectiveness of the interventions determined (not the outcome, but whether the intervention was, in fact, what the researchers thought)?
There are many intervention programs discussed in the literature. Some were conducted with some scientific care and some were done entirely for political reasons. They are discussed in some detail in The Bell Curve, Brand's The _g_ Factor: General Intelligence and Its Implications, and Jensen's The _g_ Factor. Otherwise there are many papers available. Intervention programs have not been able to produce lasting increases in measured IQ, nor have they ever been shown to have boosted _g_. Short term gains in IQ have been reported (childhood only) and are attributable to the known shared environmental factor (which vanishes) and to measurement error caused by teaching to the test.

How do these 'unparalleled' predictions compare with the decades long work of non-intelligence psychometricians?
That would be a good research project for you to undertake and to report to the rest of us. I do not know anything about non-intelligence psychometricians. In the call for papers at the upcoming ISIR conference, papers were invited on subjects pertaining to intelligence.

[Mandrake]

One would have thought that something as overwhelmingly clear as the claimed _g_/hereditability relationship would have been very easily identified, at least in terms of *some* genes.
I think I have posted information indicating that some genes have been found that are known to influence intelligence. The majority of them are known to cause decreased intelligence.

The material I have read points to the general belief that the number of genes that affect intelligence is relatively large and that the variance attributable to most of them is on the order of 1% or less. This creates a huge barrier to locating specific genes. I am not a geneticist, but I would be surprised to know that we have identified the genes that determine the shape of the human nose. It is obvious that this shape is highly heritable, yet it consists of many dimensional parameters. Do we know how many genes are involved? Have they been identified? If we wanted this information, would it be easy to find?

[Mandrake]

This questions seems so far to have gone unanswered, so I'm posting it again.

I thought I addressed it. The answer is "random error."

When _g_ is measured by one test or another test, it is somewhat colored by the structure of the test. That is the nature of testing. We have always known that the correlation between tests is not 1.0. Although the Raven's set is considered to be nearly a pure measure of _g_, it may or may not yield a _g_ that is identical to the WAIS.

[Mandrake]

To what extent do the researchers control for 'adolescence' (presumably related to hormones and physical growth) vs 'leaving the family' (going to live in a college dorm, getting married and moving out, gettin a job far from home, joining the army, whatever)? In which countries were these studies done?
The issue is not as complicated as you wish to make it. The shared environment simply does not appear in data sets where the ages are at or above 17. In any biological data, the data produce a scatter, which means that there may be cases above and below the regression line. In this case, the regression line has a nearly zero slope.

[Mandrake]

This is another of my questions that hasn't yet been answered (so I'm repeating it).

Have you attempted to answer the question with the help of a search engine? It may be difficult, for the reasons I gave in my prior message. The topic is discussed in the literature, but is tedius to locate by searching. It was addressed in Storfer's book Intelligence and Giftedness, but does not appear in the index. The same is true with the other books I have. Most are not throughly indexed.

[Tigers2B1]

Mandrake, you ever watch TV Land? On the TV Land channel there’s a program call Columbo, which features a private detective who catches his bad guy by simply using long lists of seemingly innocent questions – Columbo always seems confused --- in need of help. Then, near the end of the show, Columbo has this Got-Ya Moment when the ‘bad guy’ slips up on an answer to one of his voluminous questions.

Well, our Nereid is forever like Columbo – except he never has that Got Ya Moment.

For those unfamiliar with Columbo (but know Nereid) – I’ve linked this site ---

http://www.tvtome.com/tvtome/servlet/ShowMainServlet/showid-1011/Columbo/

[Nereid]

Mandrake, you ever watch TV Land? On the TV Land channel there’s a program call Columbo, which features a private detective who catches his bad guy by simply using long lists of seemingly innocent questions – Columbo always seems confused --- in need of help. Then, near the end of the show, Columbo has this Got-Ya Moment when the ‘bad guy’ slips up on an answer to one of his voluminous questions.

Well, our Nereid is forever like Columbo – except he never has that Got Ya Moment.

For those unfamiliar with Columbo (but know Nereid) – I’ve linked this site ---

http://www.tvtome.com/tvtome/servlet/ShowMainServlet/showid-1011/Columbo/Care to predict what the Got-Ya will be Tiger2B1?

Oh, and FYI: Nereids (http://www.pantheon.org/articles/n/nereids.html)

[Nereid]

The issue is not as complicated as you wish to make it. The shared environment simply does not appear in data sets where the ages are at or above 17. In any biological data, the data produce a scatter, which means that there may be cases above and below the regression line. In this case, the regression line has a nearly zero slope.I'm trying to understand the extent to which the terms used are clearly defined; since we're dealing with Homo sap., there are an awful lot of factors that may be relevant.

For example, if the hypothesis is something like "_g_ reaches its genetically predetermined value at the end of adolescence", then we can only satisfactorily test that hypothesis if we know what 'the end of adolescence' is. Studying how a group of individuals vary in their _g_s over time, as they transition adolescence, may be less interesting if they all reach the end of adolescence at much the same age than if they have a wide range of 'end of adolescence' ages.

BTW, don't you mean "The shared environment simply does not appear in a list of significant variables (wrt _g_) in data sets where the ages are at or above 17" (or something similar)?

[Tigers2B1]

Care to predict what the Got-Ya will be Tiger2B1?

I don’t know --- 12 more pages of questions??

[Nereid]

I don’t know --- 12 more pages of questions??Mon ami Tigers2B1, pardonnez-moi, tu et si mignon, mais semblez si stupide! Have you not been reading the posts here? :grumpy: Can you not count the number of times that hitssquad and Mandrake have given conflicting answers, to the same simple questions??

[Tigers2B1]

No, I have a part-time job stomping out crop circles for The National Enquirer you know. Plus, my cranium so big it has to be wheeled around on a tricycle --- so just give me time.

[BlackVision]

Mandrake, you ever watch TV Land? On the TV Land channel there’s a program call Columbo, which features a private detective who catches his bad guy by simply using long lists of seemingly innocent questions – Columbo always seems confused --- in need of help. Then, near the end of the show, Columbo has this Got-Ya Moment when the ‘bad guy’ slips up on an answer to one of his voluminous questions.

Well, our Nereid is forever like Columbo – except he never has that Got Ya Moment.

For those unfamiliar with Columbo (but know Nereid) – I’ve linked this site ---

http://www.tvtome.com/tvtome/servlet/ShowMainServlet/showid-1011/Columbo/
This is ALL Nereid ever does for something that she has the inability to disprove. The infamous watermelon tactic as shown here:

http://www.physicsforums.com/showthread.php?p=207833&highlight=watermelon#post207833

[Nereid]

Intelligence appears to have at least some negative correlation with parity.
How much (range)? How extensively has this been tested?
I don't know. It is something that I have seen mentioned in various books and papers as part of the discussion of within family variance. Unfortunately, Jensen's books are rather poorly indexed (unlike The Bell Curve) so it is always difficult to find material in them.

Miller says that the levels of testosterone that children are exposed to may be related to parity. Presumably he meant the intrauterine environment.

Searching my files didn't work. The problems involve multiple meanings of the term "parity" and the difficulty in removing "disparity" from the search.
This is another of my questions that hasn't yet been answered (so I'm repeating it).This is another of my questions that hasn't yet been answered (so I'm repeating it). Have you attempted to answer the question with the help of a search engine? It may be difficult, for the reasons I gave in my prior message. The topic is discussed in the literature, but is tedius to locate by searching. It was addressed in Storfer's book Intelligence and Giftedness, but does not appear in the index. The same is true with the other books I have. Most are not throughly indexed.Let's see why this might be important.

Suppose there are two population groups, one in which all the children are only childs, the other in which every family has exactly two children. Suppose the 'parity effect' is very simple, the second child has a _g_ which is 1 \sigma below that of the first child (and first children in both groups have exactly the same _g_, on average).

If nothsuR, a well-known, if somewhat controversial, psychometrican, measures the average _g_ of children in each group, controlling for all the environmental variables she knows about (but not parity), what will she find? That the second group has an average _g_ 0.5 \sigma lower than that of the first group.

Now, suppose this 'parity effect' was only discovered after the MN study was completed (and Burt long since dead); how should honest, good scientist psychometricians respond?

So, let me repeat my question, and amplify: what is the size and nature of the 'parity effect'? In which countries has it been studied? When was the first case of it being characterised (close to the contemporary consensus view)? To what extent have historical data been reanalysed to account for this effect?

[Nereid]

This is ALL Nereid ever does for something that she has the inability to disprove. The infamous watermelon tactic as shown here:

http://www.physicsforums.com/showthread.php?p=207833&highlight=watermelon#post207833Thank you for your insightful and perceptive contribution to the nature of the scientific method BV.

Perhaps you know the answer to some (one?) of my questions? How about this one:In which countries did Cattell do his research?

[BlackVision]

In which countries did Cattell do his research?
You see this? See this is the difference between you and real scientists. Actual scientists do not expect their opponents to do their research. If you wanted to find out where Cattell did his research, why would you ask your opponent instead of finding out yourself? Now I trust you've read many scientific statements by scientists that attempt to refute one another. Do you ever see them doing this? Or do you see them try to present their own evidence and attempt to counter with statements. Yes statements not questions. I know this is not something you're used to but this is the common way in one carries a debate. Presenting evidence. In which it is something you rarely do. You can not win a debate this way.

[Tom Mattson]

You see this? See this is the difference between you and real scientists.


Knock it off right now. If you don't want to answer the question, then don't answer it.

[Mandrake]

So, let me repeat my question, and amplify: what is the size and nature of the 'parity effect'? In which countries has it been studied? When was the first case of it being characterised (close to the contemporary consensus view)? To what extent have historical data been reanalysed to account for this effect?

The entire contribution from all environmental causes, plus all errors, has a variance in the range of 20% to 30% (depending on age). The parity effect is quite small. If you are interested in finding the numerical value, I gave you a good reference. Please read Storfer's book. It will not take you any longer to find it that it would take me to find it.

If the other questions are interested enough to you that you actually want to know the answers, I trust that you can find them via the same mechanisms that I would use. If you take the time to look them up, I hope you will share your findings with the rest of us.

[Nereid]

The entire contribution from all environmental causes, plus all errors, has a variance in the range of 20% to 30% (depending on age). The parity effect is quite small.Thanks Mandrake, this is helpful.

Just so that I'm quite clear though:
- this 20-30% 'environmental contribution + all errors' refers only to the US; per Jensen, insufficient work has been done to characterise these contributions - size and nature - in other countries
- 'environmental contribution' does not include factors such as illness, (head/brain) injury, 'drug taking', etc (more later)
- 'environmental contribution' does not include age (or, perhaps more accurately, _g_ is adjusted to include the observed, average age-related decline in general mental capabilities ... at least in the US); specifically, possibly irreversible declines (or advances) in _g_ due to 'lifestyle choices' are not included in the 'environmental causes'
- the 20% to 30% does include (an unquantifiable?) average 'practice effect'.

[Nereid]

If the other questions are interested enough to you that you actually want to know the answers, I trust that you can find them via the same mechanisms that I would use. If you take the time to look them up, I hope you will share your findings with the rest of us.Thanks for the comment.

What I was hoping for was access to an expert, who can quickly point a novice to online material which presents good, neutral summaries of the current state of the findings of researchers, much as many PF members do for those who enquire with physics, astronomy, etc questions.

[Nereid]

One of the things I am trying to get a better understanding of is the 'systematic errors' (to use the language of physics) that need to be accounted for - or at least identified - when reporting estimates of _g_ (or IQ) from a test given to a subject (or estimates from a meta-analysis of the reported results from many studies).

So far, thanks to Mandrake and hitssquad, I have learned that it's quite difficult to get a clear understanding of these systematic effects. Partly this seems to be because much of the research is reported in terms of correlations, and accurately translating these results into (say) 'IQ points', or 'delta _g_, measured in terms of some population standard deviation' is nigh impossible, and partly because the researchers have tried to control the test environment so as to avoid as many systematic effects as they could think of (so they don't test people who are obviously drunk, or ill, for example).

While I've not yet followed up on all the material which Mandrake and hitssquad have posted (and if it's not available online, I won't be able to), only two systematic effects appear to have been somewhat characterised: age and practice. The former seems it could be up to 30 IQ points (e.g. age 70 person vs age 20 person), the latter maybe 1 SD.

[Nereid]

or, a person is not buckyball!

While I don't think I've seen, or taken, any of the highly g-loaded tests (e.g. matrix relations), I imagine they take the form of a time-limited multiple-choice questionnaire.

It may be difficult to do 'better' in such a test simply by consciously wanting to do as well as one could, but it's certainly easy to do worse through conscious intent! For example, one could simply choose an answer at random. I'm told there's a whole global industry called 'sports psychology', which (among other things) seeks to give the sportsperson the best possible 'frame of mind' for their competition, event, or whatever. Hitssquad has told us that there is a well-known, significant 'practice effect' wrt _g_; I wonder if there is an equivalent to the sporting 'psyched to win'?

In sports you can certainly be 'psyched to lose', and you may be very conscious of some aspects of this (e.g. fear); maybe you could also be quite unconscious of an attitude or 'mental state' (sports psych speak) that predisposes you to lose (or do less than your best). Is there some equivalent wrt taking IQ tests? To what extent has this been studied?

Now, a reader may think "what a stupid question! why on earth would anyone *want* to do less than their best in an IQ test?!" To some extent this objection is irrelevant; the point is that when researchers give tests to subjects, they assume the subjects will be trying their best; from another angle, it's misplaced - for example, if your personality predisposes you to poorly in 'IQ test environments' (e.g. fear), you may not be aware that (at some level) you are 'wanting' to do less than your best.

[hitssquad]

quickly point a novice to online material which presents good, neutralThe request as stated cannot be honored. To my knowledge, techniques have not yet been developed to objectively quantitatively measure in academic material the traits good and neutral.



summaries of the current state of the findings of researchersThe most thorough review of the most broadly professionally-accepted findings regarding the g factor is Arthur Jensen's 1998 book The g Factor (http://www.questia.com/PM.qst?a=o&d=24373935). It is available online for a subscription fee (monthly, quarterly, and yearly subscriptions are available; the cost for the yearly subscription at the current discount rate works out to 30 cents USD per day).

The most thorough review of the most broadly professionally-accepted findings regarding the presence within the United States of bias in mental testing is Arthur Jensen's 1980 book Bias in Mental Testing (http://www.amazon.co.uk/exec/obidos/ASIN/0029164303). It is not available online.

[Nereid]

The request as stated cannot be honored. To my knowledge, techniques have not yet been developed to objectively quantitatively measure in academic material the traits good and neutral. :smile: Thanks hitssquad :cool:

So, how about 'good' as in 'well-written, easily readable by an non-specialist', and 'neutral' as in 'presents both mainstream views of the field as well as alternative views and critiques from related fields'. Perhaps an example might help: within astronomy and cosmology, such a paper would cover not only the concordance models (including dark matter and dark energy/quintessence/cosmological constant), but also MOND, and even plasma cosmologies.

Within the sub-discipline of intelligence psychometrics, is there a tradition of review papers?

[hitssquad]

quickly point a novice to online material which presents good, neutralTo my knowledge, techniques have not yet been developed to objectively quantitatively measure in academic material the traits good and neutral.So, how about 'good' as in 'well-written, easily readable by an non-specialist'Those are not quantities.

Jensen describes The g Factor in its Preface (http://www.questia.com/PM.qst?a=o&d=24373883) as readable by "typical ... college graduates":


A NOTE TO THE READER

Although much of the material in this book is admittedly, though unavoidably, at a fairly difficult conceptual level, I have tried to present it in such a way that it can be understood not only by specialized readers with a background in psychology, psychometrics, statistics, or behavioral genetics, but by any interested persons of whatever educational background whose reading comprehension is up to the level of what I presume is typical of college graduates. I had thought of providing a glossary of the more specialized terms, but discovered that nearly all of the entries I would have included are given quite adequate definitions in the Random House Unabridged Dictionary (Second Edition, 1993).

If you would like to judge for yourself whether the book suits your standards, Matt Nuenke has published Chapter 12 of The g Factor (http://home.comcast.net/~neoeugenics/jen12.htm) in its entirety on his website.



and 'neutral' as in 'presents both mainstream views of the field as well as alternative views and critiques from related fields'.Those also are not quantities.

I do not recall ever having read any academic publication by Jensen that did not include critiques and alternate views. Chapter 5 (http://www.questia.com/PM.qst?a=o&d=24373990) of The g Factor is devoted to "challenges to g," and Bias in Mental Testing (http://www.amazon.co.uk/exec/obidos/ASIN/0029164303) is itself composed largely of critiques and responses to those critiques.

[Mandrake]

Just so that I'm quite clear though:
- this 20-30% 'environmental contribution + all errors' refers only to the US; per Jensen, insufficient work has been done to characterise these contributions - size and nature - in other countries
Since this same question appears in many of your messages, I previously noted that I will not attempt to research it each time it is asked. The value of h^2 has been researched and reported on by psychometricians from various countries. To the best of my knowledge, there are data sets from a number of countries that have been evaluated and reported. The comments in The _g_ Factor have not been restricted to findings reported in the United States, nor to research conducted by US scientists.

- 'environmental contribution' does not include factors such as illness, (head/brain) injury, 'drug taking', etc (more later)
The above statement is incorrect. These are micro environmental factors. Macro environmental factors involve social interactions; they have a near zero presence after age 17.

- 'environmental contribution' does not include age (or, perhaps more accurately, _g_ is adjusted to include the observed, average age-related decline in general mental capabilities ... at least in the US); specifically, possibly irreversible declines (or advances) in _g_ due to 'lifestyle choices' are not included in the 'environmental causes'
Psychometric data is usually restricted in such a way as to eliminate variations that would skew the data of interest. Age is a factor in many psychometric studies and is almost always discussed in the papers. It would be silly to pretend that age related factors have no relevance to psychometric studies.

- the 20% to 30% does include (an unquantifiable?) average 'practice effect'.
Most serious psychometric research is now reported in terms of _g_. Practice can change the _g_ loading of a conventional paper and pencil test, so that variable has to be accounted for. Passive measures of _g_ by RT and electroencephalography do not show a practice effect, but these studies usually include a familiarization phase, in which the test subject becomes familiar with the test procedure. All of this is explained in detail in The _g_ Factor.

[Mandrake]

While I don't think I've seen, or taken, any of the highly g-loaded tests (e.g. matrix relations), I imagine they take the form of a time-limited multiple-choice questionnaire.
The most highly _g_ loaded standard IQ test is the Raven's (there are three tests for different levels). The appropriate method of administering this test is with no time limit. Sometimes time limits are used and do not degrade the test, if the time is generous. When time limited tests are used, the _g_ loading necessarily decreases as the time limit is shortened. This is because _g_ loading is a thinking relation. As time becomes more and more important, the _s_ loading increases. People who already have knowledge of the answer can call it up faster than those who have to think about it.

Arguably the most central of all IQ tests is the WISC, which is not a group test. It must be administered by a psychologist; some parts are timed and some are not.

For example, one could simply choose an answer at random.
That could be done with some tests and not with others. Tests administered to one person by one psychologist are not subject to such guessing. The test administrator would quickly determine that the test subject was not being cooperative and would stop the test. Given the high dollar cost of such tests, someone would be very upset with this outcome.

In sports you can certainly be 'psyched to lose', and you may be very conscious of some aspects of this (e.g. fear); maybe you could also be quite unconscious of an attitude or 'mental state' (sports psych speak) that predisposes you to lose (or do less than your best). Is there some equivalent wrt taking IQ tests? To what extent has this been studied?
There has been a good bit of study of testing errors and factors that may influence scores. Much of Bias in Mental Testing is devoted to this topic. It was necessary to evaluate this subject in order to demonstrate that it was not the cause of blacks scoring lower than any other population group. Of course the same concern exists with respect to the differences between all other population groups, but political pressure applies only to blacks. Sophisticated analysis of the tests can show such important factors as rank order difficulty. If someone takes a test and answers correctly below a given level of difficulty and then begins to answer incorrectly when the difficulty is higher, the test is probably doing its job. If he misses easy questions with an equal frequency to mid-level or hard ones, he is obviously trying to skew the results downward.

[Nereid]

Have you attempted to answer the question with the help of a search engine? It may be difficult, for the reasons I gave in my prior message. The topic is discussed in the literature, but is tedius to locate by searching. It was addressed in Storfer's book Intelligence and Giftedness, but does not appear in the index. The same is true with the other books I have. Most are not throughly indexed.I spent a fair bit of time searching the internet for results of good research into the size of the 'family size' and 'birth order' effects on _g_ (or intelligence).

I found that:
a) research seems to have been done only in countries whose economies are service-based (e.g. US, western Europe)
b) findings have been confusing and apparently contraditory - some research found a clear effect, some found none
c) the research protocol has a big impact on what the results are; e.g. across a population (at one time) vs across time (following a clearly defined group)
d) none of the sources I found online gave quantatitive results (e.g. x IQ points, with an experimental error of +/- y); plenty talked about 'the larger the family size, the lower the average IQ', or 'the more older siblings, the lower the average IQ'.

[Nereid]

Another area I researched was the relationship between language fluency and _g_ (or 'intelligence', or 'IQ'). I was interested in this because one's ability to develop a 'mother tongue' fluency in a (spoken) language becomes dramatically different for all but a fortunate few once one is past puberty. This suggests that there is some deep biological process at work in the brain, perhaps related to the processes that give rise to _g_?

I couldn't find anything! Apparently Jensen, Rushton, even the founders (Binet, Spearman) haven't researched this at all!!

Now, I'll be the first to admit that my research has been purely online, and that there could well be a veritable cornucopia of research results that I didn't find.

hitssquad, Mandrake, BlackVision, nuenke - can you help please?

What I'm looking for is any differences in the estimated _g_ of those who are at least bilingual from their earliest childhood vs those who are monolingual, or who acquired a second language essentially post-puberty. I'm referring entirely to oral capability; literacy is a different dimension which I will explore in a later post.

[Nereid]

The extent to which an individual's estimated _g_ is related to that individual's literacy (ability to read and write in their 'mother tongue') is a third area I researched (online).

The first thing I found was that such research would be difficult, if not impossible, in service-based economies; they all have 'universal education', and those who do not achieve functional literacy by adolescence (or puberty) are quite likely to have already known low _g_ (e.g. Down's syndrome, physical injury, severe drug addiction, mental illness).

Next, it seems that what little research has been done among non-literate adults, in agriculture-based economies for example, suffers from heavy biases, e.g. Rushton and Lynn's work.

Finally, there seems to have been no work done to estimate the relative _g_ impact of different writing systems (e.g. logographic vs alphabetic); indeed, the conclusion from studies which appear to show that the populations in Japan, Korea, China, Hong Kong, Singapore, Taiwan etc have a higher average IQ seems to have been 'they are genetically superior wrt _g_' rather than 'literacy based on a logographic writing system results in higher estimated _g_'

[Mandrake]

The extent to which an individual's estimated _g_ is related to that individual's literacy (ability to read and write in their 'mother tongue') is a third area I researched (online).
Literacy is presumably intended to mean "education." I have not found anything that suggests that education can raise or lower _g_. The _s_ loading of some tests is probably increased by education and may cause some measurable increase in IQ.

The first thing I found was that such research would be difficult, if not impossible, in service-based economies; they all have 'universal education', and those who do not achieve functional literacy by adolescence (or puberty) are quite likely to have already known low _g_ (e.g. Down's syndrome, physical injury, severe drug addiction, mental illness).
Within any society, there are people who get more or less education as a matter of circumstance. Not every high _g_ person is highly educated. We have discussed the cases of the people who were featured by Esquire as being among the smartest in the US. Two of the 4 hold doctorates. Two (to the best of my knowledge) hold no college level degrees. At least two are living at a level that may be fairly categorized as impoverished. Among those not listed, I know a good number (in Hi-Q societies -- way above Mensa) who have not earned college degrees. My point is that intelligence is not caused by education.

Next, it seems that what little research has been done among non-literate adults, in agriculture-based economies for example, suffers from heavy biases, e.g. Rushton and Lynn's work.
If one is studying sub-Saharan Africans, the cultures will be have little literacy and will be non-industrial. What are the "heavy biases" that you have found in their work?

Finally, there seems to have been no work done to estimate the relative _g_ impact of different writing systems (e.g. logographic vs alphabetic); indeed, the conclusion from studies which appear to show that the populations in Japan, Korea, China, Hong Kong, Singapore, Taiwan etc have a higher average IQ seems to have been 'they are genetically superior wrt _g_' rather than 'literacy based on a logographic writing system results in higher estimated _g_'
I don't know how much work has been done with respect to language. It is something to study and may have been studied. Brand has written a number of comments about deaf people, which I think may be related. For example:

... deaf children have entirely normal levels of performance on gf tests despite having missed much of the supposedly enriching and stimulating world of language and verbal communication; but, especially in childhood, they do have lower scores on gc tests requiring knowledge of language (Braden, 1994). In both cases, the tests are valid; but one type, gc, requiring normal verbal skills, registers - quite properly, and indeed quite fairly - a real handicap.(18)

... deaf children, despite their gross cultural deprivation, have no special problems with non-verbal tests that are well known as good measures of IQ.

Braden (op.cit.) especially considers the idea that minority children are handicapped in access to the ways of the 'dominant culture' - e.g. because their parents do not know it, do not like it, or anyhow cannot communicate it to their children; and thus that minority children will be deficient in the knowledge which is sometimes thought to be especially tapped by IQ-type tests. By such criteria, deaf children clearly have a massive handicap in accessing the 'dominant culture'; yet they have entirely normal levels of gf.
[Brand, C. (1996). The _g_ Factor: General Intelligence and Its Implications. Chichester, England: Wiley]

[Nereid]

Thanks Mandrake.Since this same question appears in many of your messages, I previously noted that I will not attempt to research it each time it is asked. The value of h^2 has been researched and reported on by psychometricians from various countries. To the best of my knowledge, there are data sets from a number of countries that have been evaluated and reported. The comments in The _g_ Factor have not been restricted to findings reported in the United States, nor to research conducted by US scientists.This conflicts with what hitssquad posted earlier, at least as far as Jensen is concerned. Also, in my (limited) online research, I've found that the well-controlled, lab-based, large-scale work seems to have been done almost exclusively in just a few countries, and that none come remotely close to the US in terms of quantity. Further, there are few, if any, pieces of in-depth research done in countries which are predominantly agricultural, or even industrial.

Of course, generalisation to all countries, all of Homo sap. is pervasive (again, with the notable exception of Jensen); detailed explanations for why such generalisations are justified scant.'environmental contribution' does not include factors such as illness, (head/brain) injury, 'drug taking', etcThe above statement is incorrect. These are micro environmental factors.I looked; no one seems to have attempted to study how estimates of _g_ would vary if the subjects were (for example) drunk (and quantify the effects by time and quantity of grog consumed).Macro environmental factors involve social interactions; they have a near zero presence after age 17.This statement seems to reflect research done in the US; there doesn't seem to be anything on these effects for people who reach adolescence at significantly different ages than US kids, nor who remain living with family (or an institution, e.g. priests, nuns) beyond adolescence.Psychometric data is usually restricted in such a way as to eliminate variations that would skew the data of interest. Age is a factor in many psychometric studies and is almost always discussed in the papers. It would be silly to pretend that age related factors have no relevance to psychometric studies.Quite. However, to repeat, my interest at present is systematic effects on estimates of an individual's _g_ obtained from a single test (or a series of tests done in one sitting). In this sense, your comment, while it may be accurate, is irrelevant.Most serious psychometric research is now reported in terms of _g_. Practice can change the _g_ loading of a conventional paper and pencil test, so that variable has to be accounted for. Passive measures of _g_ by RT and electroencephalography do not show a practice effect, but these studies usually include a familiarization phase, in which the test subject becomes familiar with the test procedure. All of this is explained in detail in The _g_ Factor.Jensen's? or Brand's?

I want to return to these 'passive measures', esp wrt the Flynn effect, but for now I merely note that few if any such detailed studies appear to have been done with folk other than young, literate urban adults in the US and a few other service-based economies. I also note that details of the research protocols - esp the extent to which pre-defined, double-blind ones are used, and non-manual measurement, are scanty (at least, I've not been able to find much online).

[Mandrake]

Originally Posted by Mandrake
Since this same question appears in many of your messages, I previously noted that I will not attempt to research it each time it is asked. The value of h^2 has been researched and reported on by psychometricians from various countries. To the best of my knowledge, there are data sets from a number of countries that have been evaluated and reported. The comments in The _g_ Factor have not been restricted to findings reported in the United States, nor to research conducted by US scientists.

Nereid: This conflicts with what hitssquad posted earlier, at least as far as Jensen is concerned.
Jensen is a US scientist and has done most of his work in California, presently under the rule of an Austrian.

Also, in my (limited) online research, I've found that the well-controlled, lab-based, large-scale work seems to have been done almost exclusively in just a few countries, and that none come remotely close to the US in terms of quantity.
The United States leads all countries in scientific research. Look at the Nobel Prizes in the sciences before and after WW2. There was a sudden shift from Germany to the US. I can't think of any reason to expect another country to do more research in psychometrics than would be the case in astronomy or particle physics.

Further, there are few, if any, pieces of in-depth research done in countries which are predominantly agricultural, or even industrial.
Huh? What is the point of that comment? It applies quite well to magnetic data storage, DNA research, space travel, and lasers. I don't get it. I think you have made similar comments before. Why???

I looked; no one seems to have attempted to study how estimates of _g_ would vary if the subjects were (for example) drunk (and quantify the effects by time and quantity of grog consumed).
Is there some reason why psychometricians should be looking at temporary phenomena? If someone goes to sleep, I would bet that his score on an IQ test would not be high, but that it would not be meaningful either. My prior comment was in reference to permanent environmental factors that relate to the micro environment. I could not believe that you were really asking about temporary impairment. Do you think that there is scientific research concerning human running ability? I assume there is. If so, would it be your concern that they should study runners with broken legs, drunk runners, and runners who have not eaten for six days?

Mandrake: Most serious psychometric research is now reported in terms of _g_. Practice can change the _g_ loading of a conventional paper and pencil test, so that variable has to be accounted for. Passive measures of _g_ by RT and electroencephalography do not show a practice effect, but these studies usually include a familiarization phase, in which the test subject becomes familiar with the test procedure. All of this is explained in detail in The _g_ Factor.

Jensen's? or Brand's?
As a convention, I assume that the reader understands that Jensen, A. R. (1998). The g factor: The science of mental ability. Westport, CT: Praeger, is the standard textbook in the field of psychometrics. When I wish to reference Brand's book, I do it by writing The _g_ Factor: General Intelligence and Its Implications.

I want to return to these 'passive measures', esp wrt the Flynn effect, but for now I merely note that few if any such detailed studies appear to have been done with folk other than young, literate urban adults in the US and a few other service-based economies.
This comment is not correct. Passive testing has been done in the US, Australia, New Zealand, England, and probably Germany and other countries. The IQ ranges of subjects reported by Jensen starts at around 40. Since retardation starts at 70, I do not agree that all of these subjects were literate. The service based economy thing is spurious. If you must keep including it, please explain your reason each time. Science is not dependent on whether the researchers live in a service based economy or not. I should add that you have not established that your claim is even true. I doubt that some of the contributing countries have service based economies. Would you please give us a complete list of the countries that have service based economies and some sound and verifiable information that shows your list is correct?

I also note that details of the research protocols - esp the extent to which pre-defined, double-blind ones are used, and non-manual measurement, are scanty (at least, I've not been able to find much online).
I have no idea what you are reading. The Intelligence 32-4 and 32-5 arrived in my mailbox today. A quick look through them (and any past issues) shows that your observation is false. Since you think that the US is alone in this area of science, you might be interested in the article in 32-5 by a large team of Chilean scientists who studied brain volumes, IQ, and SES. The paper includes a detailed description of the methodology and a massive presentation of the data collected, along with brain images. The subjects included both high and low SES people of both sexes. "Independently of sex, brain volume was the only brain parameter that contributed to explain IQ variance."

[Nereid]

Literacy is presumably intended to mean "education." I have not found anything that suggests that education can raise or lower _g_. The _s_ loading of some tests is probably increased by education and may cause some measurable increase in IQ.Sorry I wasn't clear; I meant basic literacy, as opposed to 'illiteracy'; I specifically do not mean 'education'. IOW, basic literacy means being able to read simple signs (e.g. "STOP", "Walk"), numbers, and in the western tradition is what most kids reach by kindergarten. AFAIK, there are hundreds of millions, possibly billions, of adults who are illiterate; for example, despite years of propoganda, it seems that a significant proportion of the adult population in China's 'countryside' are illiterate or barely literate.If one is studying sub-Saharan Africans, the cultures will be have little literacy and will be non-industrial. What are the "heavy biases" that you have found in their work?It's not only there; the majority of such folk are in Asia, particularly in China and India. In fact, it's probably less than 50 years - not even two generations - since the vast majority of Homo sap. were living in economies that were primarily agricultural (of course, it's much longer for the US and western Europe, but they comprise <15% of the world's people).

I am getting to the heavy biases; patience please. :smile:

[Nereid]

Jensen is a US scientist and has done most of his work in California, presently under the rule of an Austrian.


The United States leads all countries in scientific research. Look at the Nobel Prizes in the sciences before and after WW2. There was a sudden shift from Germany to the US. I can't think of any reason to expect another country to do more research in psychometrics than would be the case in astronomy or particle physics.


Huh? What is the point of that comment? It applies quite well to magnetic data storage, DNA research, space travel, and lasers. I don't get it. I think you have made similar comments before. Why???If all that you have is stamps (correlations), and the only stamps you have collected are from a few countries, how do you know that the rest of the world has stamps, or that they aren't made of diamond and not paper? How can you be confident that the biological correlates are the same for people whose life experiences are significantly different from those who you have studied?Is there some reason why psychometricians should be looking at temporary phenomena? If someone goes to sleep, I would bet that his score on an IQ test would not be high, but that it would not be meaningful either. My prior comment was in reference to permanent environmental factors that relate to the micro environment. I could not believe that you were really asking about temporary impairment. Do you think that there is scientific research concerning human running ability? I assume there is. If so, would it be your concern that they should study runners with broken legs, drunk runners, and runners who have not eaten for six days?To reiterate the point about correlations, if you have no idea how 'temporary phenomena' affect the arbitrary constructs you are studying, how can you tell that there aren't 'temporary phenomena' which are systematically biassing your results? Further, if you hypothesise that _g_ is something to do with brain processes, don't studies of impairment tell you a great deal? AFAIK, this is just how much progress has been made into the neurophysiology (?) of language.

To give a possibly irrelevant example; several decades ago smoking was widespread, and even then nicotine was understood to have neurological effects. Presumably Jensen et al tried very hard to control for this 'temporary phenomenon', but given the near ubiquity of the social habit, the persistence of the drug (and metabolites) in the brain, and people's imperfect veracity when it comes to reporting such habits, are you confident that the effect of smoking as a temporary phenomenon has been completely eliminated from old data?This comment is not correct. Passive testing has been done in the US, Australia, New Zealand, England, and probably Germany and other countries.All of which are service-based economies (see below)The IQ ranges of subjects reported by Jensen starts at around 40. Since retardation starts at 70, I do not agree that all of these subjects were literate.That's not my point (again, apologies for not being clear); the subjects have included few, if any, 'average' adults who just happened to be illiterate.The service based economy thing is spurious. Au contraire, mon ami! As I said above, extrapolating *correlations* found in one set of circumstances is contraindicated in good science; if all you have is correlations (and our discussion of the state of play wrt neuroscience and theory certainly seems to indicate that we've little else today), you need extremely good reasons to declare validity beyond the domains within which you obtained them.If you must keep including it, please explain your reason each time. Science is not dependent on whether the researchers live in a service based economy or not.It's not where the researchers live so much as where the *subjects* live.I should add that you have not established that your claim is even true. I doubt that some of the contributing countries have service based economies. Would you please give us a complete list of the countries that have service based economies and some sound and verifiable information that shows your list is correct?How about The World Bank? (http://www.worldbank.org/data/databytopic/labor.html) The link is to a page from which you can get employment by sector ('primary' = agriculture, fishing, animal husbandry, and mining; 'secondary' = industry; 'tertiary' = services), and also gives breakdowns by gender. The panel at the left allows you to navigate through a huge wealth of data.

Employment by sector (%; male/female; primary, secondary, tertiary):
US: 3/1; 32/12; 65/87
Australia: 6/3; 30/10; 64/87
New Zealand: 12/6; 32/12; 56/82
UK: 2/1; 36/11; 62/88
Germany: 3/2; 44/18; 52/80

Thailand: 50/48; 20/17; 30/35

Of course, these data need to be read in combination with the extensive notes; in particular, the agricultural sector for developing countries tends to be larger than the data would otherwise appear to indicate. On these World Bank pages, you will also find sector data, by economic activity (cf employment).

[Mandrake]

Mandrake:
Jensen is a US scientist and has done most of his work in California, presently under the rule of an Austrian.

The United States leads all countries in scientific research. Look at the Nobel Prizes in the sciences before and after WW2. There was a sudden shift from Germany to the US. I can't think of any reason to expect another country to do more research in psychometrics than would be the case in astronomy or particle physics.

Huh? What is the point of that comment? It applies quite well to magnetic data storage, DNA research, space travel, and lasers. I don't get it. I think you have made similar comments before. Why???

If all that you have is stamps (correlations), and the only stamps you have collected are from a few countries, how do you know that the rest of the world has stamps, or that they aren't made of diamond and not paper?
First, let me note that you did not address the issue of why it is significant, from your perspective, that the US leads all other nations in psychometric research. It does the same in most fields of science. Now, let's look at your comment above:
If all that you have is stamps (correlations)
This seems to imply that this is all that exists in psychometrics. We have discussed this topic before, but you have apparently forgotten it. Psychometrics is based on correlations AND laboratory measurements. I have previously listed the specific measurements and discussed some of them in detail. Suggesting that these don't exist comes across as very difficult to understand. Do you forget, or do you want to distort facts???
the only stamps you have collected are from a few countries

The stamp analogy is poorly considered and designed to be dismissive and misleading. The above comment is not correct. Psychometric data is collected and analyzed by scientists in a rather large number of nations. I have previously listed some and commented that the list of contributors to the journal Intelligence includes a large number of nations in each issue. The subjects of the studies include locals (from many countries) and citizens of other nations. If you really believe the things you are writing, you are misdirected to a point that your conclusions are highly likely to be incorrect (as is the case).
how do you know that the rest of the world has stamps

Stamp collecting is a canard. We know what research is being conducted in other nations by reading their published papers. I do. You apparently don't. Some of your comments indicate that you are following the discussion and asking good questions. But, then along come questions that have previously been discussed and answered.

How can you be confident that the biological correlates are the same for people whose life experiences are significantly different from those who you have studied?
Scientists study closed groups to eliminate variables. Within group studies were used to establish every point made in the first 12 chapters of The Bell Curve and the group in question was a single population group. When identical results are found between groups, there is a very high probability that the item being observed is not following different mechanistic processes in each group. You seem to be imagining how psychometric data has been collected and analyzed. I would like to suggest that a better approach would be to read what has been done, instead of guessing.

Mandrake:
Is there some reason why psychometricians should be looking at temporary phenomena? If someone goes to sleep, I would bet that his score on an IQ test would not be high, but that it would not be meaningful either. My prior comment was in reference to permanent environmental factors that relate to the micro environment. I could not believe that you were really asking about temporary impairment. Do you think that there is scientific research concerning human running ability? I assume there is. If so, would it be your concern that they should study runners with broken legs, drunk runners, and runners who have not eaten for six days?

To reiterate the point about correlations, if you have no idea how 'temporary phenomena' affect the arbitrary constructs you are studying, how can you tell that there aren't 'temporary phenomena' which are systematically biassing your results?
You are making the presumption that temporary impairment is not understood. You are wrong. I would expect that there are pertinent studies that address some forms of impairment. I have read studies that address stress as it applies to IQ testing. If you read discussions of testing procedures, you will see many discussions of factors that can adversely affect test results. Some of these are small effects and some are large. There is also a matter of common sense. It does not take a complex scientific study to determine that drunk people are not suitable for research on topics other than as they relate to drunkenness. You are imagining a bias that you have not bothered to study. The most detailed text on the subject is Jensen, A.R. (1980). Bias in mental testing. New York: Free Press. I have pointed you to this reference on several occasions.

Further, if you hypothesise that _g_ is something to do with brain processes, don't studies of impairment tell you a great deal?
Yes. The literature is rich with papers that address permanent impairment from disease and injury. Animal studies are important with respect to injury, since they include the intentional destruction of various brain regions, as I described to you in an earlier message. There may be literature on temporary impairment that extrapolates to some useful conclusions, other than that the person soul not be included in a psychometric study.

AFAIK, this is just how much progress has been made into the neurophysiology (?) of language.
What is "this?" You previously told us that neuroscience was "cool" to intelligence research. That is not true. So, I must conclude that your research into this topic should continue.

To give a possibly irrelevant example; several decades ago smoking was widespread, and even then nicotine was understood to have neurological effects. Presumably Jensen et al tried very hard to control for this 'temporary phenomenon', but given the near ubiquity of the social habit, the persistence of the drug (and metabolites) in the brain, and people's imperfect veracity when it comes to reporting such habits, are you confident that the effect of smoking as a temporary phenomenon has been completely eliminated from old data?
This is a good topic for you to research. I have not read any studies about it. What data have you seen that suggests intelligence impairment from smoking?

Mandrake:
This comment is not correct. Passive testing has been done in the US, Australia, New Zealand, England, and probably Germany and other countries.
All of which are service-based economies (see below)
The information you presented didn't list all of the countries where scientists are presently studying psychometrics. There is nothing to suggest that the science of psychometrics is actually a variable that is dependent on the number of people working in one sector or another. Psychometrics has been around for about a century. In that time the economic demographics of most advanced countries have changed. So what?

Recent studies reported in just the last two issues of Intelligence came from:
Spain, England, Chile, Ireland, Denmark, The Netherlands, Canada, Germany, Norway, Australia, France, USA, and Estonia. If you were to take the time to look back further, papers from other nations would be found. Science is science. It is practiced by nations that have enough intellect to pursue it. I doubt that you will find papers from Uganda, Kenya, Haiti, etc.

Mandrake:
The service based economy thing is spurious.

Au contraire, mon ami! As I said above, extrapolating *correlations* found in one set of circumstances is contraindicated in good science;
You have a great imagination. Populations have been studied from all over the world. Interestingly, there are studies of population groups that have lived together for centuries and studies of the same groups (genetically) within other countries (no admixture).

if all you have is correlations (and our discussion of the state of play wrt neuroscience and theory certainly seems to indicate that we've little else today)
You have not understood the discussions. We have studies based on chronometrics, electroencephalography, MRI, PET, fMRI, autopsy, and the measurement of biological parameters (such as brain pH).

Mandrake:
If you must keep including it, please explain your reason each time. Science is not dependent on whether the researchers live in a service based economy or not.
It's not where the researchers live so much as where the *subjects* live.
Yes. As we know, researchers have not confined themselves to their homelands, nor have they confined themselves to any particular type of economy.

[Nereid]

First, my thanks to Mandrake, hitssquad, Evo, Moonbear, SelfAdjoint and other posters for stimulating me to read more about this highly controversial* subject!

So, some tentative conclusions (so far). Perhaps in terms of Mandrake's opening post (http://www.physicsforums.com/showpost.php?p=292036&postcount=1)?

1 - Intelligence is best represented by _g_.
A definition, a convention, a shorthand, ... certainly bad science - tries to re-define a social construct (what Joan Public and Joe Sixpack mean when they use the word) with an abstract value obtained from statistical analysis of test results from many individuals.

2 - Virtually all of the external validity of IQ tests comes from their _g_ loading.
Circular; requires independent, objective definitions of 'IQ tests'

3 - What we know about _g_ is that it correlates strongly with various physiological conditions: nerve conduction velocity, pH, brain volume (and more specifically we now can see that particular areas of the brain are the actors and that their volumes correlate strongly with _g_), myelination, and information intake speed.
Hugely overstated; many correlations are only 'strong' wrt some found in social sciences; if examined through the lens of biology, they're weak (at best). Research results re 'particular areas of the brain' (etc) are, at best, early day results.

4 - These factors influence working memory which is now known (seen the most recent issue of the journal Intelligence) is predicted almost perfectly by _g_.
Overstated again? Statement is unclear in any case.

5 - All of the physiological measurements are seen between the population groups that are known to differ in mean IQ scores.
Vastly overstated; extensive physiological measurements, and their relationship to 'mean IQ scores' have been done in only a few countries. In this, and all the above, the results are *only* correlations (no biological hypotheses to test!)

6 - It is possible to measure _g_ by elementary cognitive tests (which are based on response time chronometrics), with a result that correlates as well with standard IQ tests as those tests correlate with each other.
Correlations have indeed been reported; the hypothesis that these correlations are universal ('apply to the mammal Homo sap. in general') has been tested in only a tiny minority.

7 - It is likewise possible to determine _g_ by electroencephalography using several different techniques and with similar accuracy.
Breath-taking extrapolation from very limited data.

8 - Both of these techniques are essentially passive, not subject to practice effects, and are totally blind to all social factors.
The first part may be accurate; the second doubtful; the third a wild assumption.

Generally, I have learned that those in the 'intelligence' field seem to reach for sweeping generalisations from their limited correlation results (Rushton and Lynn are particularly notable examples; Jensen an exception?). When faced with criticism, unlike E. O. Wilson (of sociobiology fame) who is reported to have said something like he clearly needed to do a great deal more work to establish his tentative findings, many in this field seem to have blindly carried on, finding yet more correlations (but doing little biology; there are exceptions, of course).

When compared to other fields which study how the brain works (relevance? I'd be astonished if any intelligence psychometricians claimed _g_ was *not* related to brain function!), the intelligence folk seem to have a curious reluctance to state and then test biological hypotheses. Contrast how the human vision system came to be understood (through studies of the 'visual acuity of nations'?), or how neuroscientists teased out the relationships between the three interacting sets of brain structures and the three core elements of language (crudely, semantics, phonemes, and grammar).

Or look at the extraordinarily limited basis for the sweeping claims of the genetic component. Twin studies? Only within a very narrow range of socio-economic conditions (how many New Guinea hunter gatherers? Mongolian nomadic herdsmen? Indonesian subsistance rice farmers?) which pertain to a tiny minority** of Homo sap. individuals, especially when the whole history of Homo sap. is concerned.

Some, e.g. Linda Gottfredson (Scientific American, 1998), acknowledge these limitations ("The foregoing findings on g's effects have been drawn from studies conducted under a limited range of circumstances - namely, the social, economic, and political conditions prevailing now and in recent decades in developed countries [e.g. almost all those in any list Mandrake has given] that allow considerable personal freedom. It is not clear whether these findings apply to populations around the world, to the extremely advantaged and disadvantaged in the developing world, or, for that matter, to people living under restrictive political regimes."

Reading much of this 'intelligence' literature, I was struck by the gulf between the claims (e.g. correlation does not imply causation) and the research directions (e.g. a race correlation is taken as genetic determinism).

*This is not a comment on the work of any scientist, or racist masquerading as a scientist, just an observation of the apparent public perception of the topic, at least in the US.

**Recent studies reported in just the last two issues of Intelligence came from:
Spain, England, Chile, Ireland, Denmark, The Netherlands, Canada, Germany, Norway, Australia, France, USA, and Estonia. If you were to take the time to look back further, papers from other nations would be found. Science is science. It is practiced by nations that have enough intellect to pursue it. I doubt that you will find papers from Uganda, Kenya, Haiti, etc.With the exception of Chile (population ~16 million) and Estonia (population ~1 million), but both of which are highly urban, all these are service-based economies, with near universal literacy, very low numbers of children per adult female, very low infant mortality, highly urbanised living, and so on. These conditions pertain to ~<15% of Homo sap.

[Mandrake]

So, some tentative conclusions (so far). Perhaps in terms of Mandrake's opening post?

Your comments strike me as further evidence that you are promoting a nihilistic agenda. Your conclusions are at odds with the findings of scientists who have devoted long careers to the understanding of psychometrics. When I see someone who is obviously unfamiliar with a subject attempting to dismiss it, I can only assume that the person in question is attempting to satisfy a personal or social agenda and is not attempting to fairly evaluate or discuss the topic.

I would be interested in learning your personal explanation of how it happens that you have reached conclusions that are opposite to those we find in respected scientific journals? How is it that you managed to do this so quickly? Does this indicate incompetence on the part of the people who have devoted their careers to the subject of psychometrics?

I will not bother to comment on the 8 points you dismissed, but will simply say that my reading of the literature leads me to the conclusion that your dismissive analysis is incorrect.

When compared to other fields which study how the brain works (relevance? I'd be astonished if any intelligence psychometricians claimed _g_ was *not* related to brain function!), the intelligence folk seem to have a curious reluctance to state and then test biological hypotheses.
This seems to imply that you have familiarized yourself with the literature to the point that you know this to be true. When you insert terms, such as "biological hypotheses," you imply that there is some definition of this term that excludes the various biological hypotheses that have appeared in the literature and which have been discussed here. Are you trying to play tricks with words? I have previously discussed Miller's myelination hypothesis. Why do you dismiss it? There are also various hypotheses that pertain to working memory, nerve conduction velocity, T1 and T2 relaxation times, and brain volume.

For system models, we have previously discussed the one that appears in at least three of Jensen's publications (including The _g_ Factor) and the one that appears in Brand's The _g_ Factor: General Intelligence and Its Implications. Now that we have a lot of research focused on specific locations of the brain, we have a location-specific model. See Gray, J. R., Chabris, C. F. & Braver, T. S. Neural mechanisms of general fluid intelligence. Nature Neurosci. 6, 316–322 (2003).

[Mandrake]

Or look at the extraordinarily limited basis for the sweeping claims of the genetic component. Twin studies? Only within a very narrow range of socio-economic conditions (how many New Guinea hunter gatherers? Mongolian nomadic herdsmen? Indonesian subsistance rice farmers?) which pertain to a tiny minority** of Homo sap. individuals, especially when the whole history of Homo sap. is concerned.
The above comment is a good stimulus for a discussion about the total body of evidence. Nereid's comment would lead an unsuspecting, uninformed person to the conclusion that the heritability of intelligence is based on one category of study (twins). If this were so, then her comment might merit attention. But, those who are familiar with the big picture know that the heritability of intelligence has been established and quantified by various independent means. When all vectors are pointing the same way and have the same magnitude and are determined by different categories of study, the combined certainty of the total observation is greater than even the sum of the components.

In the case of heritability, the most overwhelming evidence is from inbreeding depression. There is no other explanation for it than genetic heritability. Inbreeding depression studies not only show the expected effects, but the depression fits the magnitude of h^2 that has been determined by other means. Nereid apparently has forgotten this fact, since it has been mentioned before and is well documented in the literature. If she had bothered to read the full range of what is known about the heritability of h^2, I assume she would have discussed inbreeding depression and noted that it cannot be explained by any environmental factors.

I have mentioned path analysis on several occasions. The method of path analysis has been used to determine h^2 and produces results that are virtually identical to the other methods. Naturally, neither path analysis nor inbreeding depression depends on twins as subjects.

Besides these statistical methods, brain comparisons have been made for MZ and DZ twins using MRI. The previously referenced Gray and Thompson study shows the heritability of brain regions via MRI. ["We were stunned to see that the amount of gray matter in frontal brain regions was strongly inherited, and also predicted an individual's IQ score," said Paul Thompson, Ph.D., the study's chief investigator and an assistant professor of neurology at the UCLA Laboratory of Neuro Imaging. "The brain's language areas were also extremely similar in family members.]

It is also significant (but ignored by Nereid) that MZA studies have been carried out by a variety of researchers, at widely separated times, with different cohorts, and in different countries. The results of the studies have been remarkable for their tight consistency.

Among other factors that support the primary findings are the very high heritability of inspection time performance and the 85% heritability of brain volume. [The brain volume factor is now known to be particularly important at specific locations -- Richard Haier, previously discussed.] These factors can and have been determined independently of intelligence measurements, but are known to correlate with intelligence to such a degree that they have become central to the investigation of cognitive functioning.

Throughout science, the total body of evidence has to be taken into account as an indication of what is and what is not important. In this case, we have broad and consistent evidence from diverse observations, all pointing to the same answer. Yet, somehow, Nereid has elected to dismiss all of this. Why? I cannot understand how someone can imagine that they can find answers without effort and to have confidence that they understand the issues, without first considering the full range of facts.

There is yet another way to determine the genetic component of intelligence. It is to observe the variance that is associated with environmental factors. One way this has been done is via adoption studies. We have discussed this at length and I have pointed out that the "shared environment" component exists only in children and vanishes by late adolescence Bouchard and McGue show that the shared environment component is zero by age 12 and rises to over 80% by age 18). The remaining environmental variance is due to micro environmental factors, which amount to about 15% in adults. The error component, per Brand, is about 10%. The remainder is due to genetics.

Related to the above ...
Genetic and Environmental Influences on Human Psychological Differences
Thomas J. Bouchard, Jr., Matt McGue
Wiley Periodicals, Inc. J Neurobiol 54: 4–45, 2003
We conclude that there is now strong evidence that virtually all individual psychological differences, when reliably measured, are moderately to substantially heritable.

Additional evidence concerning the heritability of intelligence comes from the constant _g_ gap between US blacks and whites. Since intelligence data covers a relatively long period of time, one would expect that if _g_ is not primarily heritable, there would be a narrowing of the black vs. all other groups gap. During the past century blacks have enjoyed a huge gain in standard of living and especially in college education, yet the gap remains. There are but two choices: genetics and environment. The evidence is very strong that the predominant factor in the difference between various population groups is traceable to genetics. Even when adopted by white families, black children mature to have mean intelligence values that match those of their genetic peers who were not adopted. Likewise, Asian children mature to match the intelligence means of their genetic peers (which happens to mean that they have higher mean intelligence than their adoptive families -- opposite to the case of blacks adopted by whites in the US and Europe.

[Mandrake]

Some, e.g. Linda Gottfredson (Scientific American, 1998), acknowledge these limitations ("The foregoing findings on g's effects have been drawn from studies conducted under a limited range of circumstances - namely, the social, economic, and political conditions prevailing now and in recent decades in developed countries [e.g. almost all those in any list Mandrake has given] that allow considerable personal freedom. It is not clear whether these findings apply to populations around the world, to the extremely advantaged and disadvantaged in the developing world, or, for that matter, to people living under restrictive political regimes."
There is good reason to conclude that the same factors that relate to intelligence in the US or Europe also relate in other nations. Within the US, we have large populations of the major population groups and they have been studied for nearly a century. Most of the research has been within-group. When a mechanism is found in group A and in group B and both are seen to act identically, it is not an unfair extrapolation to conclude that the differences in mean values between the groups is subject to the same factors as the differences that are found within group.

While there may well be environmental factors that account for some of the large difference between sub-Saharan Africans and US blacks, there is little to suggest that these factors can be large enough to erase the difference. As much as you would apparently like to discredit Lynn and Rushton, I see no reason to believe that you have a better understanding of this science than these two people who have devoted their lives to actual measurements.

Reading much of this 'intelligence' literature,
Much??? How much do you define as "much?" My impression is that you have not yet read enough to even connect the dots on a single psychometric issue, such as heritability. Have you read "much" of the literature on intelligence?

I was struck by the gulf between the claims (e.g. correlation does not imply causation) and the research directions (e.g. a race correlation is taken as genetic determinism).
I would like to suggest that you use quotes from the literature (you have read "much" of it) instead of making assertions that are actually your thoughts. It is impossible to discuss specific issues when one is offering only vague and unsupported assertions. Just tell us what some respected psychometrician has written, tell us his name, and then let us discuss whether or not that person has been scientifically naïve, or not.


Originally Posted by Mandrake
Recent studies reported in just the last two issues of Intelligence came from:
Spain, England, Chile, Ireland, Denmark, The Netherlands, Canada, Germany, Norway, Australia, France, USA, and Estonia. If you were to take the time to look back further, papers from other nations would be found. Science is science. It is practiced by nations that have enough intellect to pursue it. I doubt that you will find papers from Uganda, Kenya, Haiti, etc.
With the exception of Chile (population ~16 million) and Estonia (population ~1 million), but both of which are highly urban, all these are service-based economies, with near universal literacy, very low numbers of children per adult female, very low infant mortality, highly urbanised living, and so on. These conditions pertain to ~<15% of Homo sap.
There are three major racial groups and a number of identifiable population groups. The major groups have been studied extensively and are well understood with respect to the parameters that consistently appear within and between groups. It is, as you should know, not true to imply that groups in various parts of the world have been studied, but it is correct that they have not been studied as extensively as has been the case for population groups within Europe and the US. If one simply writes off all groups that have not been extensively studied, nothing changes with respect to the knowledge of psychometrics.

Meanwhile, there remains one fact that cannot be disputed and that is that population groups having very low mean intelligence scores have performed as a group in a manner that can be projected by IQ scores. We have been through this line before and it is beyond argument. Likewise, population groups that have high mean IQs have shown accomplishment that is in line with high intelligence.

[selfAdjoint]

I have read Nereid's post twice, carefully, and I just wnat to make one comment. It is an old story for hard scientists to show contempt for the .3 - .7 correlations considered highly significant in the human sciences - this happens throughout these sciences, not just in the IQ area. But that is what nature gives the human scientists, and when they do their math carefully, the difference between correlations of +.3, 0, and -.3 is perfectly clear, and meaningful. Yes it isn't quantitative at the level that astronomical evidence is, but that doesn't mean it's a hash.

Well, I said only one comment but here's another. Nereid, can you confirm that you really studied the modern fMRI-g experiments? Your dismissal of them didn't seem to describe them as I understood them from reading the papers.

[Tigers2B1]

It’s my understanding that g is a construct used to describe the phenomenon witnessed when a person makes similar scores on differently constructed, but complex tests of mental ability. Like the construct ‘energy’ that is used to describe events in physics --- while a physicist may have never seen an ‘energy,’ the idea / construct has value and describes the witnessed phenomenon. So, for example, if a person scores a 140 in a spatial relations subgroup in one test, that person is very unlikely to score an 80 in the numerical reasoning subgroup – even though spatial relations and numerical reasoning may have no other relationship outside of the complexity of the problems. The construct g describes this. It describes the ability to ‘figure out’ complex problems. The same phenomenon was observed inter-test -- in that the same person is very unlikely to score a 140 on the Raven Matrix IQ test and score an 80 on another test, if that test uses mentally complex problems - like complex pattern problems. The harder the solution is to find for the average test taker, the more likely the solution calls on reasoning abilities that can translate to other mental abilities and to other tests of mental ability.

In Bias in Mental Testing, p. 250, Arthur Jensen summarizes the construct this way:

By examining the surface characteristics of a great variety of tests in connection with their g loadings, we may arrive at some descriptive generalizations about the common surface features that characterize tests that have relatively high g loadings as compared with tests that have relatively low g loadings. Today we have much more test material to examine for this purpose than was available to Spearman more than half a century ago. This permits broader generalizations about g than Spearnan could safety draw. Spearman characterized the most g-loaded tests essentially as those requiring the subject to grasp relationships—“the eduction of relations and correlates.” That is all perfectly correct. But now we can go further. The g factor is manifested in tests to the degree that they involve mental manipulation of the input elements (“fundaments” in Spearman’s terminology), choice, decision, invention in contrast to reproduction, reproduction in contrast to selection, meaningful memory in contrast to rote memory, long-term memory in contrast to short-term memory, and distinguishing relevant information from irrelevant information in solving complex problems. Although neither the forward nor backward digit-span test of the Wechsler Intelligence Scale, for example, has much g loading. the slightly greater mental manipulation required by backward than by forward recall of the digits more than doubles the g variance in backward as compared with forward digit span (Jensen & Figueroa, 1975). We have seen many examples in which a slight increase in task complexity is accompanied by an increase in the g loading of the task. This is true even for the most mundane and seemingly nonintellectual tasks. Virtually any task involving mental activity that is complex enough to be recognized at the commonsense level as involving some kind of conscious mental effort is substantially g loaded. It is the task’s complexity rather than its content that is most related to g.

[Nereid]

I have read Nereid's post twice, carefully, and I just wnat to make one comment. It is an old story for hard scientists to show contempt for the .3 - .7 correlations considered highly significant in the human sciences - this happens throughout these sciences, not just in the IQ area. But that is what nature gives the human scientists, and when they do their math carefully, the difference between correlations of +.3, 0, and -.3 is perfectly clear, and meaningful. Yes it isn't quantitative at the level that astronomical evidence is, but that doesn't mean it's a hash.Hmm, I'm not sure what a 'human science' is, but fMRI ... 'race' (biological definition (whatever that is), not a social construct) ... frequency of alpha brain waves ... ECT ... latency and amplitude of evoked brain potentials ... hereditability (genetic, not social or cultural) ... rate of brain glucose metabolism ... brain volume ... are not terms one commonly finds in sociology texts I would guess. PF members Moonbear (http://www.physicsforums.com/showpost.php?p=318087&postcount=97) and Phobos (http://www.physicsforums.com/showpost.php?p=317622&postcount=91) have commented on how 'hard' biology is.

Maybe 'intelligence science' just got a whole lot 'harder'?

[selfAdjoint]

fMRI has done nothing to refute, and everything to confirm, the concept of g. And yes I have given you references on that before. Let's not just rehash the whole thread all over again. Frequency of brain waves does not yet bear on the issue AFAIK. Heritability is supported by extensive careful twin studies which show those .3 - .7 correlations you don't like. And I do remember your attempts to undercut those studies, which, I am afraid I have to say, reminded me of nothing so much as the attempts of posters on the Astronomy forums to undercut the Hubble expansion with cherry-picked observations. What if this, what if that, we can't accept the studies till they have answered every question I can think up. Sorry for the rough speech but it comes honestly.

[Roberth]

I have come across this debate by chance (my main interest is physics) and in a way I am sad about it. It does strike me, however, and therefore I will comment.

What happened to the old and widely correct saying:

"IQ tests measure how well you do on IQ tests!"

Rather than going into a long essay, I will simply make a few points.

1) There has never been a consensus what 'intelligence' actually means. The one that I can best subscribe to is Piaget's. To paraphrase him: "intelligence is what you use when you don't know what to do".

2) IQ tests measure convergent intelligence and there are only a very few tests around which measure divergent intelligence (the closest to creativity). Creativity is at least as, if not more important, than analytical thinking, verbal abilities and all the other classical IQ test areas.

3) There are no good tests around that measure abstraction skills. This ability is definitely one of the key factors that distinguishes a mere high IQ person from an "intellectually intelligent" person. The same is true for people with average intelligence.

4) The most viable numbers on the nature-nurture debate are 60% to 80%. This can mean a difference between an IQ of 78 and 130!

5) Has anybody ever come up with a test measuring the ability for 'deeper insight'? This is a long-term cognitive ability but related to EQ. Many people would agree that this is a strong indication of 'intelligence'. I am not convinced that many people with high IQs are particularly good in this area. Conversely, low level IQ people can certainly have the quintessential deeper insight, 'wisdom'.

6) The practicing side is widely underestimated in IQ tests. Language abilities fall in this category. For example, I do not think that Arnold Schwarzenegger would either in English nor in German (his mother tongue) achieve 85% of the result that he achieved when he was 20 (before he moved to the US). His English skills never reached his mother tongue level and his mother tongue level has deteriorated since he moved to the US, 30 years ago.

7) There have been several racial crossing studies which show that there is no significant difference in IQ between races (eg. Eyferth 1961, Tizard 1972, Scarr and Weinberg 1976)

etc.

The major question of this thread, however, remains an ethical one, particularly when it comes to cross-racial studies. I love science and, after physics, psychology has always been my favorite area (I have some formal education and also used it professionally).

The questions are: What is the purpose of these cross-racial IQ studies? Why are people doing them? What knowledge do these studies add that is of any value to anybody?

I cannot see any potential benefits of these cross-racial studies that would outweigh the damage that they create in society.

Roberth

"Now, winning the Nobel prize is one thing, but winning it with an IQ of only 125, that is really something!" - Richard Feynman

[Aquamarine]

Roberth:
I think the objections to IQ and IQ tests have been answered in this thread and others in this forum.
The major question of this thread, however, remains an ethical one, particularly when it comes to cross-racial studies. I love science and, after physics, psychology has always been my favorite area (I have some formal education and also used it professionally).

The questions are: What is the purpose of these cross-racial IQ studies? Why are people doing them? What knowledge do these studies add that is of any value to anybody?

I cannot see any potential benefits of these cross-racial studies that would outweigh the damage that they create in society.
I agree that the world would be nicer if these results were wrong. Well, they are not and denial of reality will not help when making decisions.

A more intelligent minority in many countries have a disproportionate share the nations wealth. If the IQ results are accepted, it is possible to see that the minority creates more wealth than otherwise also for the majority. Denial is the path to genocide and poverty, like in Germany, Zimbabwe and so many other places and times before. It is no coincidence that the Nazis forbid IQ tests.

[Aquamarine]

If the majority is more intelligent, it is not a good solution for the economy to discriminate them, like in affirmative action. It is better for all to help the minority more directly. Also, the minorities can have other advantages that they should concentrate on instead. For example, blacks may have greater physical abilities and social skills than whites/East Asians. If so, they should concentrate on occupations like sales.

[Roberth]

I think the objections to IQ and IQ tests have been answered in this thread and others in this forum.

Yes. The question is what you mean by 'answered'. They certainly cannot mean refuted, but I will leave it at that.


I agree that the world would be nicer if these results were wrong. Well, they are not and denial of reality will not help when making decisions.

This is not a question of denial. I believe that the results are correct and certainly do not believe that anybody tinkered with the IQ test results. I am not so sure about their other studies which 'prove' that lack of IQ is hereditary. The problem remains what good these studies do. They certainly do not produce any scientifically important data, but can create harm.

I give you a counterexample, it would be far better if psychologists
concentrated on looking at patterns and techniques that could help people of poorer social environments to develop their mental skills.

What do you think most people will think reading these test results? Will they think

A. Aah, look the black people are less clever than we are and it is unfortunately in their genes. These poor guys, let's help them so that they get a similar standard of living to what we have ….

or

B. Well, I always knew that, just look at their behavior. It is certainly not my fault that so many of them have to live in ghettos …..

Hmm, what do you think?

The point again is, the attempt to statistically prove that a certain race is 'by nature' less intelligent does not help anybody. It is beside the point whether people do not agree with these test result conclusions. I also do not believe that the Asians or whoever are more intelligent by nature - but even if they are, so what?


A more intelligent minority in many countries have a disproportionate share the nations wealth. If the IQ results are accepted, it is possible to see that the minority creates more wealth than otherwise also for the majority.

I do not believe that. See A. and B. above.


Denial is the path to genocide and poverty, like in Germany, Zimbabwe and so many other places and times before. It is no coincidence that the Nazis forbid IQ tests.

I have not heard that before about the Nazis but believe you. The probable reasons were that they wanted to
1. keep the master race myth in tact. Imagine the Jews and other minorities would have turned out as clever.
2. not undermine their own structure. The follower of the Nazis regime were not very educated and probably would have done less than average on IQ tests.

Anyway, the US is certainly not in the same situation as Germany under Hitler. What is good in one situation (like it may have been at the time in Germany) can be bad in another.

If the majority is more intelligent, it is not a good solution for the economy to discriminate them, like in affirmative action.

I do not understand this statement.

It is better for all to help the minority more directly.

Agreed

Also, the minorities can have other advantages that they should concentrate on instead. For example, blacks may have greater physical abilities and social skills than whites/East Asians. If so, they should concentrate on occupations like sales.

Uuooh …, there we go. What comes next? Categorizing into Alphas, Betas etc. and creating a Brave New World?
I think that you mean well, but be careful with these schemes. They have never worked.

[Aquamarine]

I don't believe in censoring science due to the assumption that people will make the wrong decision if told the truth. Who are you to decide for them? That is very close to a dictatorship.

Society should certainly not try to give everybody exactly the same standard of living. That is the socialistic road to hell on this Earth, with over 100 million dead since 1917. The important thing is to reduce the absolute level of poverty, not that everybody is equal. Available research overwhelmingly shows that the road to long-term reduction of poverty and more wealth for all is more capitalism. There are good theoretical reasons for this, but the empirical evidence should be enough.
http://www.cato.org/research/articles/vas-0109.html
http://www.freetheworld.com/papers.html

People with different ability and success should be payed accordingly. Long-term, this has given more wealth to all persons in capitalistic societes, including those with less ability, when the total amount of wealth available increases faster.

Regarding affirmative action, if less productive people takes the place of more productive, the wealth of society as whole will be reduced. And since the wealth grows exponentially, all reductions will have a large effect long-term. If one wants to help those with less ability, it should be directly, not though discrimination of those with more ability.

Regarding successful minorities, if people are not censored and learn that this is due to higher intelligence and not to injustice and conspiracy, there will be less genocides and poverty for all.

[CloakNight]

What happened to the old and widely correct saying:

"IQ tests measure how well you do on IQ tests!"
IQ tests measure intelligence. Repeated studies show it's very accurate in measuring Spearman's g. And I'm not sure what you mean by "old and widely" saying because it seems it has always been accepted that IQ measure intelligence.

1) There has never been a consensus what 'intelligence' actually means.
Spearman's g.

2) IQ tests measure convergent intelligence and there are only a very few tests around which measure divergent intelligence (the closest to creativity). Creativity is at least as, if not more important, than analytical thinking, verbal abilities and all the other classical IQ test areas.
Creativity is not intelligence.

4) The most viable numbers on the nature-nurture debate are 60% to 80%. This can mean a difference between an IQ of 78 and 130!
Where are you getting this from? How did you get 78 and 130? You seem to be taking 130 and subtracting 40% from it. That is NOT how it works. The genetic correlation of IQ has been said to be .7 or .8. This is quite high. People that do take IQ tests over and over again, It's rare that they'll fluctuate more than a few points.

5) Has anybody ever come up with a test measuring the ability for 'deeper insight'?
Irrevelant as IQ test is suppose to measure one thing. General intelligence.

I am not convinced that many people with high IQs are particularly good in this area.
A person with a high IQ can be bad at basketball but you still forget that IQ tests are suppose to measure plain intelligence. Nothing else.

6) The practicing side is widely underestimated in IQ tests. Language abilities fall in this category. For example, I do not think that Arnold Schwarzenegger would either in English nor in German (his mother tongue) achieve 85% of the result that he achieved when he was 20 (before he moved to the US). His English skills never reached his mother tongue level and his mother tongue level has deteriorated since he moved to the US, 30 years ago.
IQ tests do not require high language ability as it is not a test to measure knowledge. Raven's Progressive Matrices would require NO language ability at all. But I would suspect Arnold Schwarzenegger would be able to take a Weschler IQ test in either German or English with no problems.

7) There have been several racial crossing studies which show that there is no significant difference in IQ between races (eg. Eyferth 1961, Tizard 1972, Scarr and Weinberg 1976)
Again where are you going this from? Something is fishy here. You're definitely not telling something.

Repeated studies year after year show about a 15 point IQ gap between Whites and American Blacks. About a 3-6 point IQ gap between Whites and East Asians. This has been quite consistent. Opponents against the Bell Curve have never actually argued against these figures but attempt to say that the difference is mostly or purely environmental. The American Psychological Association has also confirmed that the widely reported 15 point gap between Whites and Blacks is accurate.

The questions are: What is the purpose of these cross-racial IQ studies? Why are people doing them? What knowledge do these studies add that is of any value to anybody?
What purpose? For science. For knowledge. For understanding. Why study anything? Scientists study them because they wish to find the truth.

What does the study on how the moon formed attribute to any value? It's knowledge. There is an enormous gaps in academic ability between races throughout the world. Whether in America or Europe or Australia, etc. Some scientists wish to find out why. Certainly a politically incorrect topic but that does not mean one shouuldn't strive to find the truth to this matter.

I cannot see any potential benefits of these cross-racial studies that would outweigh the damage that they create in society.
What damage? There was a lot of people like you when Darwin came out. Stating that implying that humans evolved from lesser life forms instead of being the creation of God will create damage in society. Create less happiness in people who otherwise wish to believe there is a God looking after us, we are God's creations, and there is a heaven to go to after we part from this Earth. So what's the good in knowing evolution is real? It's simply to know the truth.

"Now, winning the Nobel prize is one thing, but winning it with an IQ of only 125, that is really something!" - Richard Feynman
Yes that is something. The average Nobel Prize winner (science departments) is about 155 however. A figure less than 0.1% of the population will have.

[Roberth]

I don't believe in censoring science due to the assumption that people will make the wrong decision if told the truth. Who are you to decide for them? That is very close to a dictatorship.

This is an old and widely debated argument and I was sure that it would come up.

There is and must be an ethic of science. To simple say: "I am a scientist and my only goal in life is finding The Truth!" is very naïve.
Scientists are human and have also other, conscious and unconscious, motives than 'Finding the Truth'. If a scientific investigation can obviously hurt and be used as a weapon, either physical or social, then this constitutes an area that has to be addressed very cautiously. If, like in this case, there is no benefit to anybody then you must be even more careful.

Imagine I was interested in a certain experiment in Physics for the 'sake of truth'. The experiment does not add anything useful to the progress of mankind but can be dangerous. Do you think that people will agree to that? I hope not.

I then shout: "This is dictatorship! You want to undermine the truth!"

Research into nuclear fusion would be a counter example. Although there are some risks, the benefits of a future clean and virtually limitless power source for all mankind far outweighs the connected risks.

It has nothing to do with dictatorship but with responsibility. To quote a famous comic figure that I often read in my teens:
"With great power comes great responsibility" - Words and research are a great social power!


Society should certainly not try to give everybody exactly the same standard of living. That is the socialistic road to hell on this Earth, with over 100 million dead since 1917. The important thing is to reduce the absolute level of poverty, not that everybody is equal. Available research overwhelmingly shows that the road to long-term reduction of poverty and more wealth for all is more capitalism. There are good theoretical reasons for this, but the empirical evidence should be enough.
http://www.cato.org/research/articles/vas-0109.html
http://www.freetheworld.com/papers.html

I widely agree with you on that point, although capitalism often goes too far. There are different ways to employ capitalism.

People with different ability should be rewarded accordingly. In the end, that will give more wealth to all.

I agree with you in principle although the mechanism of wealth redistribution is severely lacking in the US and also some other parts of the western world. Without distribution only a few are helped and there is not more wealth to all but only a few.

Regarding affirmative action, if less productive people takes the place of more productive, the wealth of society as whole will be reduced. And since the wealth grows exponentially, all reductions will have a large effect long-term.

First, the wealth cannot grow exponentially for very much longer. The resources of our world are limited. It is about time that people understand that.
Earth will fight back against being increasingly exploited or may die as an inhabitable place within the next few generations - but this is another topic.
Point is: increasingly higher production is not necessarily good. Have you thought about what would happen if all 6 Billion people in the world would have the same standard of living as people in the US and the rest of the Western World?

It can actually be good that people become less productive and focus on other things than material gain - but that is also another topic.

It is again about responsibility. Future generations will judge us.

Regarding successful minorities, if people are not censored and learn that this is due to higher intelligence and not to injustice and conspiracy, there will be less genocides and poverty for all.

Fine, then these psychologists should test a fair sample of 20% of the high earners in the US and show that they have a higher IQ (which I believe they do). Doing this, they will have achieved their goal and can then work towards less genocides and poverty for all.

Roberth

[selfAdjoint]

Roberth, you several times repeat that you are talking about responsibility, not coercion, but your methods seem to be that other people (who?) enforce this "responsibility" upon a scientist who may not agree with them. Isn't that the definition of coercion? And just who is "responsible" in such a situation?

[Roberth]

IQ tests measure intelligence. Repeated studies show it's very accurate in measuring Spearman's g. And I'm not sure what you mean by "old and widely" saying because it seems it has always been accepted that IQ measure intelligence.


Spearman's g.

Yes, I was talking about Spearman's g amongst other and it has not always been accepted that IQ measure intelligence. That is the whole point here.

Creativity is not intelligence.

In the sense of Piaget (and others) it is.

Where are you getting this from? How did you get 78 and 130? You seem to be taking 130 and subtracting 40% from it. That is NOT how it works. The genetic correlation of IQ has been said to be .7 or .8. This is quite high. People that do take IQ tests over and over again, It's rare that they'll fluctuate more than a few points.

I did mean percentage point of IQ and not correlation.

Irrevelant as IQ test is suppose to measure one thing. General intelligence.

Exactly, supposed to but other psychologists (and I agree with them) say that it only does in a very limited way.

A person with a high IQ can be bad at basketball but you still forget that IQ tests are suppose to measure plain intelligence. Nothing else.

Depends on the definition of intelligence again, see above.

IQ tests do not require high language ability as it is not a test to measure knowledge. Raven's Progressive Matrices would require NO language ability at all. But I would suspect Arnold Schwarzenegger would be able to take a Weschler IQ test in either German or English with no problems.

Although Raven's test is pretty good, it is not as cultural-free as some people claim. There are several counter studies.

Do you mean the IQ test created by David Wechsler in 1939?

As far as verbal IQ goes, ask any professional linguist and they will agree with me. That is the reason why professional linguists usually only translate into their mother tongue and not vice versa. Furthermore, when you do not practise a language for a long time you loose skill in it. A bit like playing chess, really.

Again where are you going this from? Something is fishy here. You're definitely not telling something.

Where am I getting this from? From university study books in Psychology amongst other. It's part of studying psychology. No Conspiracy here.

I wonder why you do not know them?

Repeated studies year after year show about a 15 point IQ gap between Whites and American Blacks. About a 3-6 point IQ gap between Whites and East Asians. This has been quite consistent. Opponents against the Bell Curve have never actually argued against these figures but attempt to say that the difference is mostly or purely environmental. The American Psychological Association has also confirmed that the widely reported 15 point gap between Whites and Blacks is accurate.

I do not dispute that. I question that this measures 'inherent intelligence'. See my answer to Aquamarine.

What purpose? For science. For knowledge. For understanding. Why study anything? Scientists study them because they wish to find the truth.

What does the study on how the moon formed attribute to any value? It's knowledge. There is an enormous gaps in academic ability between races throughout the world. Whether in America or Europe or Australia, etc. Some scientists wish to find out why. Certainly a politically incorrect topic but that does not mean one shouuldn't strive to find the truth to this matter.

I could not care less whether something is politically incorrect or not. The point is that it does not add anything except mostly harmful adversary.
See my answer to Aquamarine.

What damage? There was a lot of people like you when Darwin came out. Stating that implying that humans evolved from lesser life forms instead of being the creation of God will create damage in society. Create less happiness in people who otherwise wish to believe there is a God looking after us, we are God's creations, and there is a heaven to go to after we part from this Earth. So what's the good in knowing evolution is real? It's simply to know the truth.

I doubt that there were people like me.

It was not Darwin who created problems but some of the epigons that used it to 'prove' whatever their motivational disposition was.

I give you one severe example. There was a 'scientist' called Agassiz who claimed that:
"The brain of the Negro is that of the imperfect brain of a seven months old infant in the womb of a white". Page 127, Ontogeny and Phylogeny, by Stephen Gould.


Yes that is something. The average Nobel Prize winner (science departments) is about 155 however. A figure less than 0.1% of the population will have.

Really? Interesting and quite plausible. I believe you but would like to know how this is known. Have they gone through IQ tests before their Nobel prize speech?

[Mandrake]

What happened to the old and widely correct saying:
"IQ tests measure how well you do on IQ tests!"
Sayings do not constitute science. IQ tests measure group factors and _g_. If these were worthless, there would be no concern over IQ tests and they would have vanished long ago. They persist because they measure a fundamental variance in human ability and are useful both for prediction and explanation of differences in such important matters as rate of learning, ability to perform tasks that are limited by intelligence thresholds, academic performance, and job performance.

1) There has never been a consensus what 'intelligence' actually means. The one that I can best subscribe to is Piaget's. To paraphrase him: "intelligence is what you use when you don't know what to do".
Please give a reference for the above. The quote you gave has been attributed (by Jensen) to Carl Bereiter.

2) IQ tests measure convergent intelligence and there are only a very few tests around which measure divergent intelligence (the closest to creativity).

Please tell us what recognized psychometric texts confirm your assertion. I am more familiar with the literature than most people and have yet to see a single discussion that asserts anything about "convergent intelligence." Would you provide a definition and a source for the definition? Thank you.

Creativity is at least as, if not more important, than analytical thinking, verbal abilities and all the other classical IQ test areas.
Lots of things are important to human life, including honesty, beauty, health, charm, persistence, and zeal. None of these diminish the importance of the others, nor of intelligence.

3) There are no good tests around that measure abstraction skills. This ability is definitely one of the key factors that distinguishes a mere high IQ person from an "intellectually intelligent" person. The same is true for people with average intelligence.
Why do you offer such assertions without providing names and validation findings? We would be interested to know the names of those "good tests" and to see data which compare their ability to predict against the ability of _g_ to predict in areas such as learning rate, job performance, academic performance, income, SES, etc.

4) The most viable numbers on the nature-nurture debate are 60% to 80%. This can mean a difference between an IQ of 78 and 130!
I think you have already been taken to task for the above nonsense.

6) The practicing side is widely underestimated in IQ tests. Language abilities fall in this category. For example, I do not think that Arnold Schwarzenegger would either in English nor in German (his mother tongue) achieve 85% of the result that he achieved when he was 20 (before he moved to the US). His English skills never reached his mother tongue level and his mother tongue level has deteriorated since he moved to the US, 30 years ago.
What is the definition of "the practicing side?" Is this a scientific term? I note that you were critical of the term "intelligence." Is "the practicing side" more precise?

7) There have been several racial crossing studies which show that there is no significant difference in IQ between races (eg. Eyferth 1961, Tizard 1972, Scarr and Weinberg 1976)
What is a "racial crossing study?" Perhaps a study of Michael Jackson from childhood to present?

Scarr and Weinberg conducted a transracial adoption study (there was no mention of racial crossing in the papers I read). The report in 1976 showed the effects of shared environment, which were assumed to be permanent. Somehow you forgot to tell us about the follow-up study in 1986. Why? The report then found that the shared environmental factor was zero. It is now known that the shared environmental factor is present in childhood, but that it vanishes around age 12 to 17. (Plomin gives age 12.)

The major question of this thread, however, remains an ethical one, particularly when it comes to cross-racial studies.

What is a "cross-racial study?" Psychometricians usually speak of within group and between group studies. I assume you mean "between group," but you used "racial." Various population groups are known to have different mean values of intelligence.

The questions are: What is the purpose of these cross-racial IQ studies? Why are people doing them? What knowledge do these studies add that is of any value to anybody?
People study between group factors in order to understand the subject of intelligence and in order to create tools that can explain the variances that are observed in both individual and group performance. The same considerations apply to other between group studies, such as are common in medicine and physiology.

One example of what has been learned from population group studies (but must be ignored by politicians and academics) is that _g_ cannot be changed by any macro environmental conditions. No form of education, or change to family environment (even adoption) will cause a change in adult _g_. This tells us that attempting to produce equal test scores for schools with different population group weightings is impossible. Kansas City and Detroit have spent huge sums of money trying to demonstrate that poor school performance is the result of low budgets. They were not able to raise test scores for the simple reason that it is not possible to create tests that require thought but which do not tap _g_. Save the money. Washington, DC has one of the highest per student spending rates in the nation and the lowest test scores.

I cannot see any potential benefits of these cross-racial studies that would outweigh the damage that they create in society.
Your assertion of damage is unsupported. There is no damage.

"Now, winning the Nobel prize is one thing, but winning it with an IQ of only 125, that is really something!" - Richard Feynman
The claim that Feynman had an IQ of 125 was included in one of the books of Feynman stories written by Ralph Leighton. There is no information in the book that tells us anything about the test, such as its name, how it was given, its validity, its standard deviation, etc. Without that information, the claim is simply silly (even if Feynman believed it). Jensen was asked about the 125 claim; his reply has been copied here more than once, so I will not bother to do it again. In essence, Jensen said that the claim was very unlikely to be correct. People who want to rail against IQ, however, are quick to latch on to this as if it were a scientific fact.

If you enjoyed the Feynman stories, as I did, may I suggest that you read (presumably again) the one on page 60 of What Do You Care What Other People Think?

===

This is not a question of denial. I believe that the results are correct and certainly do not believe that anybody tinkered with the IQ test results. I am not so sure about their other studies which 'prove' that lack of IQ is hereditary. The problem remains what good these studies do. They certainly do not produce any scientifically important data, but can create harm.
Your wording is odd, so I have to guess that you do not believe that the variance in IQ is attributable to genetics. If so, I would like to suggest that your opinion is at odds with the findings of very well conducted research that has shown the value of h^2 as a function of age and which has shown that it can be demonstrated by multiple independent methodologies. Your assertion that scientific findings (such as the value of h^2) cause harm is a personal opinion, not a fact.

What do you think most people will think reading these test results? Will they think
A. or B.
Hmm, what do you think?
I think that there are differences in mean IQ for a number of population groups and that the within group differences are caused by genetics, just as the between group differences are caused by genetics at rates that are a function of age (70% in young adults, rising to 80% or more in older adults).

[Mandrake]

There is and must be an ethic of science. To simple say: "I am a scientist and my only goal in life is finding The Truth!" is very naïve.
I disagree. Truth is the only reasonable goal in science.

Scientists are human and have also other, conscious and unconscious, motives than 'Finding the Truth'. If a scientific investigation can obviously hurt and be used as a weapon, either physical or social, then this constitutes an area that has to be addressed very cautiously. If, like in this case, there is no benefit to anybody then you must be even more careful.
Your assertion concerning truth as a weapon is baseless and obscene. Concealing the truth is a crime against nature.

Research into nuclear fusion would be a counter example. Although there are some risks, the benefits of a future clean and virtually limitless power source for all mankind far outweighs the connected risks.
This has nothing to do with the subject at hand. As a technicality, it is also misleading, since the production of energy by fusion necessarily involves the production of radioisotopes, which are not "clean."

[Mandrake]

Although Raven's test is pretty good, it is not as cultural-free as some people claim. There are several counter studies.
Why didn't you list the studies? Please list them now. What were the findings that you believe are most significant?

Do you mean the IQ test created by David Wechsler in 1939?
Surely you know that the Wechsler tests are the most central to psychometrics and have been constantly updated. You surely must also know that there are multiple tests in use that are variants of the Wechsler and which use the name Wechsler.

Where am I getting this from? From university study books in Psychology amongst other. It's part of studying psychology. No Conspiracy here.

I wonder why you do not know them?
And I wonder why you do not list them. Just so we know your sources, please tell us which psychometrics textbooks you have read from cover to cover and tell us which textbooks you implied but failed to list in your comment. Your various comments indicate to me a very limited understanding of this subject.

I do not dispute that. I question that this measures 'inherent intelligence'.
What do your textbooks define as "inherent intelligence?" It seems to me that there is only one really significant aspect of cognitive performance that is addressed by psychometrics and that is psychometric _g_. Anything beyond that is the subject of a different discussion.

I give you one severe example. There was a 'scientist' called Agassiz who claimed that:
"The brain of the Negro is that of the imperfect brain of a seven months old infant in the womb of a white". Page 127, Ontogeny and Phylogeny, by Stephen Gould.
What is the reason for your above comment? It appears to be race baiting to me. Why is it important to quote from a person who died 25 years before the first intelligence test? And why would any person quote from the discredited Stephen Gould, who never even demonstrated that he understood factor analysis? Gould used every means possible in "Mismeasure" to distort the truth and to mislead ignorant readers who didn't know any better than to accept his comments at face value.

[Aquamarine]

Regarding successful minorities, if people are not censored and learn that this is due to higher intelligence and not to injustice and conspiracy, there will be less genocides and poverty for all.
Fine, then these psychologists should test a fair sample of 20% of the high earners in the US and show that they have a higher IQ (which I believe they do). Doing this, they will have achieved their goal and can then work towards less genocides and poverty for all.
People probably already assume that high earners have greater IQ. But also that if a racial minority have disproportionate wealth, it means injustice or conspiracy has occurred. That is the natural conclusion if races have equal IQ. And that righteous redistribution, violent if necessary, will make the majority richer. That is what happened in Germany in the thirties and in Zimbabwe today.

I will answer the objections to capitalism in a separate thread.

[Roberth]

Roberth, you several times repeat that you are talking about responsibility, not coercion, but your methods seem to be that other people (who?) enforce this "responsibility" upon a scientist who may not agree with them. Isn't that the definition of coercion? And just who is "responsible" in such a situation?


These are, of course, very valid questions. I will answer soon.

Roberth

[Roberth]

Sayings do not constitute science. IQ tests measure group factors and _g_. If these were worthless, there would be no concern over IQ tests and they would have vanished long ago. They persist because they measure a fundamental variance in human ability and are useful both for prediction and explanation of differences in such important matters as rate of learning, ability to perform tasks that are limited by intelligence thresholds, academic performance, and job performance.

Are you a psychologist or only a psychometrician? If you are a psychologist then you should be able to answer the question why these IQ tests have not vanished, yet. I give you a hint: it has something to do with the psychological disposition of those people who advocate them.

And why do you want to make those predictions and for what purpose? Pre-destine the fate of the lower IQ people? These studies neither help to improve these important matters nor do they help in any way to improve the situation for the people concerned. See my previous posts.


Please give a reference for the above. The quote you gave has been attributed (by Jensen) to Carl Bereiter.

How Brains Think, page 1 by William H. Calvin

Please tell us what recognized psychometric texts confirm your assertion. I am more familiar with the literature than most people and have yet to see a single discussion that asserts anything about "convergent intelligence." Would you provide a definition and a source for the definition? Thank you.

"Convergent thinking is a cognitive style characterized by a tendency to focus on a single best solution to a problem", used by J.P. Guilford, Getzel and Jackson, Wallach and Kogan, Hudson and others.

What is the problem here? This is the second time that I have been asked about terminology which should be second nature to a 'Psychologist', but some people on this board have never heard it.

I can assume that their studies must be unbalanced and one-sided.

This may the crux to this problem in the first place. In the 'investigating' Arts and soft Sciences, if you do not learn to apply the principle of dialectic then your conclusions will remain superficial. Psychology is a soft Science. Even in the exact Sciences this principle has its good virtue.

Lots of things are important to human life, including honesty, beauty, health, charm, persistence, and zeal. None of these diminish the importance of the others, nor of intelligence.

Yes.

There are no good tests around that measure abstraction skills. This ability is definitely one of the key factors that distinguishes a mere high IQ person from an "intellectually intelligent" person. The same is true for people with average intelligence.


Why do you offer such assertions without providing names and validation findings? We would be interested to know the names of those "good tests" and to see data which compare their ability to predict against the ability of _g_ to predict in areas such as learning rate, job performance, academic performance, income, SES, etc.

My point was that there are no real good tests around to measure abstraction skills. You then ask me, why I cannot provide you with those good tests …???

Regarding the _g_ test, I am aware of its correlation significance. The argument in itself is not very difficult to understand. The danger, however, is that you want to use it to predict in areas such as learning rate, job performance, academic performance, income, SES, etc.
Leave out the prediction, it does not help anybody!

I think you have already been taken to task for the above nonsense.

I stay with it, however, and will not go into useless proofs or otherwise. As far as your nonsense statement is concerned, our knowledge again seem to differ.


What is the definition of "the practicing side?" Is this a scientific term? I note that you were critical of the term "intelligence." Is "the practicing side" more precise?

Do you really need a definition of what 'practicing a language' means? Most people will probably understand without a definition. I am starting to have my doubts, however. I was not critical of the term intelligence, I was critical of what is understood by it. The term 'intelligence' is certainly a lot more abstract than what the expression 'practicing a language' means.


What is a "racial crossing study?" Perhaps a study of Michael Jackson from childhood to present?

"Racial crossing studies focus on black, white and mixed-race children who happen to be raised in similar environmental circumstances".

Please hold back criticizing expressions that you do not know! It is petty and not very productive and only shows the fact that you do not know them (you may know them under a different name).

Scarr and Weinberg conducted a transracial adoption study (there was no mention of racial crossing in the papers I read). The report in 1976 showed the effects of shared environment, which were assumed to be permanent. Somehow you forgot to tell us about the follow-up study in 1986. Why? The report then found that the shared environmental factor was zero. It is now known that the shared environmental factor is present in childhood, but that it vanishes around age 12 to 17. (Plomin gives age 12.)

Does it? So be it. However, has anybody tried to produce a counter-argument? I cannot comment since I do not know this 1986 study.


One example of what has been learned from population group studies (but must be ignored by politicians and academics) is that _g_ cannot be changed by any macro environmental conditions. No form of education, or change to family environment (even adoption) will cause a change in adult _g_. This tells us that attempting to produce equal test scores for schools with different population group weightings is impossible. Kansas City and Detroit have spent huge sums of money trying to demonstrate that poor school performance is the result of low budgets. They were not able to raise test scores for the simple reason that it is not possible to create tests that require thought but which do not tap _g_. Save the money. Washington, DC has one of the highest per student spending rates in the nation and the lowest test scores.

So, they were not able to raise test scores? … and now they should spend less money? Well, you see that is the problem that I ethically have with your attitude: You now end up with the conclusion that it may be a waste of money to try to bring up the level of people in Kansas City and Detroit. It can never be a waste of money to give people a chance. Furthermore, less ideologically, I am not at all convinced that the mental capabilities of people are predetermined to an extent that there is no hope whatever you do, regardless their test scores.

In case you get the wrong impression, I do not believe that you can make a genius out of a person with limited genetic material (now, that sounds charming, doesn't it?), but you can get a very long way of improving their overall cognitive capabilities.

IQ tests are simply not general enough to justify any decision-making process for individual persons.


Your assertion of damage is unsupported. There is no damage.

Are you really that naive?

The claim that Feynman ... ...were a scientific fact.

Well, in the story that I remember he actually said it himself.

You see what you are doing now? You want to prove to all people with an IQ of less or equal than 125 to never try to win the Nobel Prize (by the way, it is not about winning the Nobel Prize, it is about the achievement that goes with it).

If you want to do use these tests for a positive purpose then find other people where the gap between their IQ and their positive achievement is very high. Investigate the cognitive and personality-related traits that make them successful and give other people the chance to learn from it.

Your wording is odd, so I have to guess that you do not believe that the variance in IQ is attributable to genetics. If so, I would like to suggest that your opinion is at odds with the findings of very well conducted research that has shown the value of h^2 as a function of age and which has shown that it can be demonstrated by multiple independent methodologies. Your assertion that scientific findings (such as the value of h^2) cause harm is a personal opinion, not a fact.

I do not only question the validity of these research studies but also question what they are good for. Besides, there is very well conducted research that shows the opposite.

I think that there are differences in mean IQ for a number of population groups and that the within group differences are caused by genetics, just as the between group differences are caused by genetics at rates that are a function of age (70% in young adults, rising to 80% or more in older adults).

Is this a comment to the following passage from above?

What do you think most people will think reading these test results? Will they think

A. Aah, look the black people are less clever than we are and it is unfortunately in their genes. These poor guys, let's help them so that they get a similar standard of living to what we have ….

or

B. Well, I always knew that, just look at their behavior. It is certainly not my fault that so many of them have to live in ghettos …..

Hmm, what do you think?

I think that you totally missed the point here. Please read it again.

[Roberth]

I disagree. Truth is the only reasonable goal in science.

No, it is not the only one and can never be.

Your assertion concerning truth as a weapon is baseless and obscene. Concealing the truth is a crime against nature.

The only crime against nature is when people are not humble against her creation. One example is the arrogance that perceived truth will justify unethical and damaging measures.

This has nothing to do with the subject at hand. As a technicality, it is also misleading, since the production of energy by fusion necessarily involves the production of radioisotopes, which are not "clean."

That is what I meant by saying "some risks".

Why didn't you list the studies? Please list them now. What were the findings that you believe are most significant?

The issue here is not that I have to show them, the issue here is that you do not know them. Look them up in the literature or search on the Internet.

Surely you know that the Wechsler tests are the most central to psychometrics and have been constantly updated. You surely must also know that there are multiple tests in use that are variants of the Wechsler and which use the name Wechsler.


Yes. I asked because Aquamarine wrote "Weschler" (which is also a possible name of German origin).

And I wonder why you do not list them. Just so we know your sources, please tell us which psychometrics textbooks you have read from cover to cover and tell us which textbooks you implied but failed to list in your comment. Your various comments indicate to me a very limited understanding of this subject.

Now, now, be careful what you say: it is the other way round. So far I have had no problems to follow your assertions but you seem to lack some balanced view of the subject to be able to follow mine.


What do your textbooks define as "inherent intelligence?" It seems to me that there is only one really significant aspect of cognitive performance that is addressed by psychometrics and that is psychometric _g_. Anything beyond that is the subject of a different discussion.

Do you really not know what 'inherent' means? With the rest, you finally hit the jackpot. The problem is that this significant aspect is far too limited and this was my point in the first place.

What is the reason for your above comment? It appears to be race baiting to me. Why is it important to quote from a person who died 25 years before the first intelligence test? And why would any person quote from the discredited Stephen Gould, who never even demonstrated that he understood factor analysis? Gould used every means possible in "Mismeasure" to distort the truth and to mislead ignorant readers who didn't know any better than to accept his comments at face value.

The example shows how dangerous it can be to use these racial differentiating studies. Stephen Gould is discredited? By who? … and what does it change in respect to this point?

[Mandrake]

And why do you want to make those predictions and for what purpose? Pre-destine the fate of the lower IQ people? These studies neither help to improve these important matters nor do they help in any way to improve the situation for the people concerned.
You seem to think that IQ tests are a weapon to be used against stupid people. One of the important uses of IQ (previously discussed in this forum - read and learn) testing is to locate individuals who have high cognitive ability so that they can be given encouragement and aid in achieving an education that is appropriate to their abilities. It is for that reason that Harvard led the way to the now standard practice of seeking and recruiting brilliant students for slots in our top universities. In the past, those slots were offered only on the basis of SES.

See my previous posts.
Yeah, really. I have seen that your comments are aggressive towards a science that you obviously have not taken time to understand. Instead of telling me to read your posts, I would like to suggest that you read mine before rehashing material that has been explained in detail, with cited reference sources.

Please give a reference for the above. The quote you gave has been attributed (by Jensen) to Carl Bereiter.

How Brains Think, page 1 by William H. Calvin
Either your source is wrong or mine is wrong. My source is Jensen, A. R. (1998). The g factor: The science of mental ability. Westport, CT: Praeger, page 111
This reminds one of Carl Bereiter's clever definition of "intelligence" as "what you use when you don't know what to do."

Please tell us what recognized psychometric texts confirm your assertion. I am more familiar with the literature than most people and have yet to see a single discussion that asserts anything about "convergent intelligence." Would you provide a definition and a source for the definition? Thank you.

"Convergent thinking is a cognitive style characterized by a tendency to focus on a single best solution to a problem", used by J.P. Guilford, Getzel and Jackson, Wallach and Kogan, Hudson and others.
So, can you tell us why you bothered to type out the quote yet were unwilling to give the name of the publication?

What is the problem here? This is the second time that I have been asked about terminology which should be second nature to a 'Psychologist', but some people on this board have never heard it.
The problem is that the words "convergent thinking" do not appear at a detectable frequency in psychometric papers and textbooks. I just now did a search of the database (Jan 1977 to present) of the journal Intelligence. The phrase "convergent thinking" did not appear even once!

Regarding the _g_ test, I am aware of its correlation significance. The argument in itself is not very difficult to understand. The danger, however, is that you want to use it to predict in areas such as learning rate, job performance, academic performance, income, SES, etc.
Leave out the prediction, it does not help anybody!

I disagree with your opinion. I have already explained how IQ is used to help place intelligent people in top universities. At the other end of the scale, the US military uses IQ to exclude people from military service. You should have already read about this several times, since I have presented it with the source (Detterman). The reason for exclusion, even in time of war, is that our military has found that it is difficult to impossible to properly train recruits below the cut points (the Navy cut is IQ 91). Placing low IQ people in positions where their performance is likely to influence casualty rates is unacceptable. It is similarly silly to send low IQ people off to universities where they cannot hope to do the required work or to have them enroll in a curriculum that is known to have a threshold of performance well above their ability level.

What is a "racial crossing study?" Perhaps a study of Michael Jackson from childhood to present?

"Racial crossing studies focus on black, white and mixed-race children who happen to be raised in similar environmental circumstances".
Why did you present a quote without identifying its source? Are you attempting to appear as well informed when you are not? If your source is a peer reviewed journal or a recognized psychometric textbook, we will understand. If it is now, we will also understand. Why must you continually play the above trick of using quotes without attribution? As a matter of interest, would you also list for us the "racial crossing studies" in question? Did the scientists who conducted those studies actually use the terminology "racial crossing studies?" I think you are reading from general sources and not the papers of the scientists who did the studies.

Please hold back criticizing expressions that you do not know!
I am familiar with the literature and I know that the expression you used was not used in any source that I have seen and that I have read the primary papers on this subject. As a confirmation, I searched for "racial crossing" in the Intelligence database (Jan 1977 to present). The two words were not used together even once.

It is petty and not very productive and only shows the fact that you do not know them (you may know them under a different name).
It might be petty. My point is that you are so unfamiliar with the literature that you are using language that is not being used by researchers. You conveniently make assertions without attributing them to verifiable sources. This all adds up to obvious ignorance of the subject. It is okay that you haven't done your homework, but it is not productive to pretend otherwise.

Scarr and Weinberg conducted a transracial adoption study (there was no mention of racial crossing in the papers I read). The report in 1976 showed the effects of shared environment, which were assumed to be permanent. Somehow you forgot to tell us about the follow-up study in 1986. Why? The report then found that the shared environmental factor was zero. It is now known that the shared environmental factor is present in childhood, but that it vanishes around age 12 to 17. (Plomin gives age 12.)

Does it? So be it. However, has anybody tried to produce a counter-argument? I cannot comment since I do not know this 1986 study.
It is obvious that you are not even familiar with the now common knowledge that the effects of shared environment vanish. I suggest that a good starting point for you would be to carefully read Jensen's The _g_ Factor.

So, they were not able to raise test scores? … and now they should spend less money?
When the stated objective of spending the money was to raise test scores and the result obtained was that test scores did not improve, one must assume that there might be a better way to use that money.
More Money Better Education?
Walter E. Williams, February 1, 1999
New Jersey ranks number one in the nation in terms of expenditures per student ($10,900). Washington, D.C. is a close second at $10,300. If educationists are right, New Jersey and Washington, D.C. should have the highest level of student achievement in the land. Think again. New Jersey ranks 29th in student achievement. As for Washington, D.C., the only thing preventing it from being dead last in student achievement is Mississippi.

Minnesota ranks first in nation in terms of student achievement and Iowa ranks second. If we accepted the more-money-better education sham, we'd think Minnesota and Iowa are really up there in per student expenditures. Think again. Minnesota ranks 27th in expenditure per student ($6,300) and Iowa ranks a lowly 30th ($6,000). There is no relation between expenditures and student performance.


Well, you see that is the problem that I ethically have with your attitude: You now end up with the conclusion that it may be a waste of money to try to bring up the level of people in Kansas City and Detroit. It can never be a waste of money to give people a chance.
Spending more money on schools does not cause test scores to go up. There was no question of "giving people a chance." They had a chance and they had a second chance. The problem is that the people who spend the money don't understand what will and what will not work.

[Mandrake]

Furthermore, less ideologically, I am not at all convinced that the mental capabilities of people are predetermined to an extent that there is no hope whatever you do, regardless their test scores.
This depends on how one defines "hope." If you hope to increase _g_ by schooling, the hope is false. If you hope to teach people to the extent that their abilities permit, then that could be done, but only if one first dumps PC ideas.

IQ tests are simply not general enough to justify any decision-making process for individual persons.
Fortunately, you are wrong. IQ tests can and do identify people who (despite their SES, secondary education, race, or other factors) can succeed in the most demanding universities.

Your assertion of damage is unsupported. There is no damage.
Are you really that naive?
Your assertion is hollow and you know it. We can clearly see that you have not supported your claim.

The claim that Feynman ... ...were a scientific fact.

Well, in the story that I remember he actually said it himself.
The author attributed the comment to Feynman. The point is that there is no reason to believe that it was accurate.

You see what you are doing now? You want to prove to all people with an IQ of less or equal than 125 to never try to win the Nobel Prize (by the way, it is not about winning the Nobel Prize, it is about the achievement that goes with it).
I am not doing anything other than pointing out that the 125 claim is silly. You should read the comments (elsewhere in this forum) to see what Jensen had to say about the claim. As for winning the Nobel Prize, do you have any information that even one person has won the prize in a science category with an IQ as low as 125? Intelligence works as a threshold for the grasping of various tasks. Once the threshold is crossed, people can function with the task. I contend that the threshold for doing work that will earn a Nobel Prize is probably around +2 sigma.


Your wording is odd, so I have to guess that you do not believe that the variance in IQ is attributable to genetics. If so, I would like to suggest that your opinion is at odds with the findings of very well conducted research that has shown the value of h^2 as a function of age and which has shown that it can be demonstrated by multiple independent methodologies. Your assertion that scientific findings (such as the value of h^2) cause harm is a personal opinion, not a fact.

I do not only question the validity of these research studies but also question what they are good for. Besides, there is very well conducted research that shows the opposite.
Precisely what is "the opposite?" Please list for us the research studies you have in mind (but intentionally did not reference). Who conducted the studies? What peer reviewed papers contain the results? What were the primary findings? Are those findings accepted as accurate by any respected psychometricians?

[Roberth]

This depends on how one defines "hope." If you hope to increase _g_ by schooling, the hope is false. If you hope to teach people to the extent that their abilities permit, then that could be done, but only if one first dumps PC ideas.


Fortunately, you are wrong. IQ tests can and do identify people who (despite their SES, secondary education, race, or other factors) can succeed in the most demanding universities.


Your assertion is hollow and you know it. We can clearly see that you have not supported your claim.


The author attributed the comment to Feynman. The point is that there is no reason to believe that it was accurate.


I am not doing anything other than pointing out that the 125 claim is silly. You should read the comments (elsewhere in this forum) to see what Jensen had to say about the claim. As for winning the Nobel Prize, do you have any information that even one person has won the prize in a science category with an IQ as low as 125? Intelligence works as a threshold for the grasping of various tasks. Once the threshold is crossed, people can function with the task. I contend that the threshold for doing work that will earn a Nobel Prize is probably around +2 sigma.



Precisely what is "the opposite?" Please list for us the research studies you have in mind (but intentionally did not reference). Who conducted the studies? What peer reviewed papers contain the results? What were the primary findings? Are those findings accepted as accurate by any respected psychometricians?

This is totally ridiculous and I therefore will write a final summary to clarify open questions and then stop with this discussion. I no longer wish to waste my time with this intellectual banality of finding references referring to references and the justifying of psychological insight in the context of psychometric tunnel vision.

Summary

In this whole discussion you constantly referred to these self-referential papers in your psychometric database and journal of Intelligence. This explains to me why you lack any wider outlook on the subject and miss common psychological insight.

Several of the references and terms that I quoted or used are from one of my study books that were used as part of a degree in psychology several years ago.

Introduction to Psychology,
The Open University, volume 1
A total of 16 professors and researchers produced that book (and I will not list them here now). You find them on the back cover of the first page of this book.

Regarding the term "divergent and convergent intelligence". How is it possible that I make a simple search in Google on the Internet and find the term and you are not?

Here is a link to one of my hits
Laboratory Exercise for General Experimental Psychology

By the way, it is in fact totally irrelevant to anything where the term comes from, it is its meaning that it important.

I also looked around if I could find something that more or less summarizes my views and knowledge. I found this site

/drives/f/httpd/web/psych/iqnotes.htm

It is from Professor Mackintosh of the Department of Experimental Psychology at the University in Cambridge.

It is only in list form but most people will probably get the contents of the important points. It also mentions Jensen who seems to be so highly regarded by you.
If you do not understand the points or words, or wish to know important references referring to other references which then hopefully refer to your database, then I would suggest to get in touch with them.

Real psychology and the conscientious application of it is a very worthwhile and rewarding endeavor and psychometric methods have their place in it. However, the way you portrayed it, it is one-sided, tunnel-visioned, unethical, damaging, naive and intellectually banal.

Roberth

[Mandrake]

Mandrake:
I disagree. Truth is the only reasonable goal in science.
No, it is not the only one and can never be.
Your comment is an opinion that is not shared by many scientists. Science is about truth. People who don't understand that should go into politics, where dishonesty is commonplace.

Originally Posted by Roberth
Although Raven's test is pretty good, it is not as cultural-free as some people claim. There are several counter studies.

Mandrake:
Why didn't you list the studies? Please list them now. What were the findings that you believe are most significant?
The issue here is not that I have to show them, the issue here is that you do not know them. Look them up in the literature or search on the Internet.
The issue here is that you made an assertion without any support for it. I contend that your comment is incorrect. It makes sense that you don't want to justify it, since you probably cannot. When someone makes an assertion, it is his responsibility to support it, not the responsibility of anyone else. Based on the general level of information you have presented here, it is obvious that you are not informed about the Raven's cultural loading. If you are, why are you hiding your knowledge?

Where am I getting this from? From university study books in Psychology amongst other. It's part of studying psychology. No Conspiracy here.
Mandrake:
And I wonder why you do not list them. Just so we know your sources, please tell us which psychometrics textbooks you have read from cover to cover and tell us which textbooks you implied but failed to list in your comment. Your various comments indicate to me a very limited understanding of this subject.

Now, now, be careful what you say: it is the other way round. So far I have had no problems to follow your assertions but you seem to lack some balanced view of the subject to be able to follow mine.
So, you cannot support your "study books" comment. I am not surprised. You assert, but you do not support. If you are reading undergraduate textbooks, I doubt that you have ever encountered the material from recognized psychometric researchers. You have quoted material that was so old that it was refuted by the researchers who initially reported it and to my amazement, you referenced a guy who died a quarter of a century before the first intelligence test. Is this the kind of material you find in "study books?"

Mandrake:
What do your textbooks define as "inherent intelligence?" It seems to me that there is only one really significant aspect of cognitive performance that is addressed by psychometrics and that is psychometric _g_. Anything beyond that is the subject of a different discussion.
Do you really not know what 'inherent' means?
I didn't ask you the definition of "inherent" did I? Please answer the question I presented. You were critical of the word "intelligence," but you then proceeded to use made up words and phrases that are not found in contemporary psychometric papers. Perhaps you would like to list for us, just two or three peer reviewed papers in this decade that use the words "inherent intelligence?" Where do you get this stuff? Either you have a reference with a definition for it or you made it up. I suspect the latter.

[Mandrake]

I give you one severe example. There was a 'scientist' called Agassiz who claimed that:
"The brain of the Negro is that of the imperfect brain of a seven months old infant in the womb of a white". Page 127, Ontogeny and Phylogeny, by Stephen Gould.

Mandrake:
What is the reason for your above comment? It appears to be race baiting to me. Why is it important to quote from a person who died 25 years before the first intelligence test? And why would any person quote from the discredited Stephen Gould, who never even demonstrated that he understood factor analysis? Gould used every means possible in "Mismeasure" to distort the truth and to mislead ignorant readers who didn't know any better than to accept his comments at face value.

The example shows how dangerous it can be to use these racial differentiating studies.

No, the example shows that you quoted material from a Swiss guy who died in 1873. How and why did you select that person? Do you think that he was aware of any aspect of modern psychometrics? I consider your use of this material as race baiting and an obvious attempt to avoid a discussion of modern science.

Stephen Gould is discredited? By who? … and what does it change in respect to this point?

If you have read the literature you already know the answer, since Gould has been discredited by many of the most respected psychometricians around the world.

To the best of my knowledge, Gould's only attempt to publish in the area was his book Mismeasure of Man. It was a book that was appreciated only by people who didn't know better. I have a homework assignment for you. Please read this link in its entirety:
http://tinyurl.com/43f59
The comments are from the most respected and knowledgable psychometrician alive -- Jensen.

If it is unclear, please read it a second time. Gould played a prominent role in a group called Science for the People and in that group's attack on the theories of Harvard zoologist Edward 0. Wilson, a leader in the development of sociobiology (BioSciences, March, 1976, Vol. 26, No. 3). (Gould was a trouble maker, not a psychological researcher.)

Reflections on Stephen Jay Gould's The Mismeasure of Man (1981):

JOHN B. CARROLL, University of North Carolina at Chapel Hill A Retrospective Review in Intelligence 21, 121-134 (1995)
Gould's research on the history of craniometry is interesting and possibly valuable for historians of science. His account of the history of mental testing, however, may be regarded as badly biased, and crafted in such a way as to prejudice the general public and even some scientists against almost any research concerning human cognitive abilities. In this account, he indicts mental testing not only as racially motivated, at least in its beginnings, but more importantly, as ethically and scientifically flawed because it "reifies" the IQ as a single number that places a value on a test result.

It is indeed odd that Gould continues to place the burden of his critique on factor analysis, the nature and purpose of which, I believe, he still fails to understand. Even if factor analysis had never been invented, we would nonetheless have IQ tests and many other kinds of aptitude tests measuring various cognitive abilities. And there would still be "experts" dealing with the construction, analysis, and interpretation of these tests, and behavioral geneticists (Plomin & McClearn, 1993) concerned with the heritability of the traits measured by these tests.

'The 'g' Factor'is a book about human intelligence. In particular, it tries to answer social-environmentalists and methodological solipsists such as Professors Leon Kamin, Steve Gould, Steve Rose and Steve Jones -- the self-appointed arch-critics of 'general intelligence' ('g') today (though only Kamin is himself a psychologist). [Christopher Brand]

Stephen Jay Gould (1983) argued that factor analysis is not an appropriate way of defining the variables underlying test scores, because one solution is statistically as a good as another. Gould was wrong. There are statistical methods (which were well known to specialists at the time) that make it possible to compare the goodness of fit of one factor-analytic solution to another. When these methods are applied, investigators virtually always find a highly reliable first factor.
...
Gould claimed that psychometricians could not distinguish between alternative factor structures. Today they can.
[The Role of Intelligence in Modern Society by Earl Hunt]

Gould is correct in stating that there are alternative methods with the same overall power to account for the correlations among the tests. But he is wrong when he implies that by using an alternative method, an analyst can get rid of g. As Richard Herrnstein liked to say, "You can make g hide, but you can't make it go away."

Gould's position, then, has been thoroughly discredited among scholars, however dominant it remains in the media. Had he kept quiet about The Bell Curve or attacked it on other grounds, his view might have continued to hold sway there. But when he repeated the same arguments in his New Yorker review - which I am told has been triumphantly circulated by nonpsychologists as the canonical refutation of The Bell Curve -he accomplished something that Herrinstein and I could not have done: he made scholars who know what the evidence shows angry enough to go public.
Upstream: Issues: The Bell Curve: The Bell Curve and its Critics
Charles Murray
Commentary, May 1995 v99 n5 p23(8)

[Mandrake]

This is totally ridiculous and I therefore will write a final summary to clarify open questions and then stop with this discussion. :surprised
Good choice. It offers you an opportunity to save face and avoids the necessity of trying to support claims and quotes that have no known sources.

I no longer wish to waste my time with this intellectual banality of finding references
You wrote material in quotes. If you have the sources to copy, why do you refuse to identify the papers and authors? Why did you once present names of people without any list of papers or textbooks? If you know what you are quoting, you should be able to simply give the references, as I have repeatedly done.

In this whole discussion you constantly referred to these self-referential papers in your psychometric database and journal of Intelligence. This explains to me why you lack any wider outlook on the subject and miss common psychological insight.
My insight is based on having read massive amounts of material for a dozen years. I know what research has been done, who did it, and what it does or does not demonstrate. You apparently have restricted your reading to Gould and some general undergraduate or high school level books on psychology.

Several of the references and terms that I quoted or used are from one of my study books that were used as part of a degree in psychology several years ago.
If your degree in psychology is not a graduate degree, I can understand your obvious confusion. Your comments are not consistent with what is known and reported in present day peer reviewed sources.

Introduction to Psychology, The Open University, volume 1
A total of 16 professors and researchers produced that book (and I will not list them here now). You find them on the back cover of the first page of this book.
Sorry, I don't read "introductory" books. It is unlikely that you can find anything of depth in such a book. I don't blame you for not listing the "professors" as I doubt the names would match those who publish research papers in this field.

Regarding the term "divergent and convergent intelligence". How is it possible that I make a simple search in Google on the Internet and find the term and you are not?
Your use of the term demonstrates the level of material you are using for reference. If you think this is a real psychometric term, please demonstrate it. Intelligence is best represented by _g_.

I also looked around if I could find something that more or less summarizes my views and knowledge. I found this site
/drives/f/httpd/web/psych/iqnotes.htm
It is from Professor Mackintosh of the Department of Experimental Psychology at the University in Cambridge.
It is only in list form but most people will probably get the contents of the important points.
I hope you are not implying that Mackintosh has the same level of understanding of psychometrics that you have demonstrated here. Are you familiar enough with computers to recognize a functional URL? The one you gave is not in the proper format.

Macintosh is best known for his 1995 publication of a book that discussed the details of the Burt affair. It appears that Burt was falsely accused, but possibly sloppy.

It also mentions Jensen who seems to be so highly regarded by you.
I respect Jensen for the same reason that others respect him. He is simply the most knowledgable and honest scientist in the field of intelligence research. He has contributed more to the field than anyone alive and probably ranks with Charles Spearman in terms of his overall impact on the understanding of differential psychometrics. Anyone who has even a slight interest in psychometrics should have read generously from his papers and books.

If you do not understand the points or words, or wish to know important references referring to other references which then hopefully refer to your database, then I would suggest to get in touch with them.
I am not suffering from a lack of understanding in this area. Your level of expertise is obvious. The terminology you have used is not found in serious psychometric literature, but I don't doubt that it can be found in "study books" for undergraduates or high school students.

Real psychology and the conscientious application of it is a very worthwhile and rewarding endeavor and psychometric methods have their place in it. However, the way you portrayed it, it is one-sided, tunnel-visioned, unethical, damaging, naive and intellectually banal.

Your observation comes from the perspective of a publicly displayed level of competence which requires no further comment. I suggest that, if this topic is interesting to you, that you should read modern texts and papers, putting fourth enough effort to understand the material. I think you will find it rewarding and may even encourage you to return to discuss your newfound knowledge here.

[Evo]

Mandrake, you are a wealth of misinformation, as always.

I haven't even bothered reading the rest of your spam and I don't plan to. You keep regurgitating the same nonsense.

[Mandrake]

Mandrake, you are a wealth of misinformation, as always.

I haven't even bothered reading the rest of your spam and I don't plan to. You keep regurgitating the same nonsense.

Hi Evo!

It's great to hear from you again. I always look forward to your warm and cheerful comments. Your insight here has been truly extraordinary. Keep up the good work, as we all appreciate encouragement from those elders for whom we hold high personal regard.

As you know, I started this successful thread on August 22nd. Since then, the discussion has been one of the most successful ever, attracting 232 posts and a whopping 3565 viewers (and growing). Obviously this topic is one that interests many participants. We have seen a good number of very well informed people offer their comments and insight (none approaching yours though). Even the people who have presented comments that were not supportable or even those that have been churlish, have helped maintain lines of discussion and have thusly brought additional information to benefit all.

When we compare the high interest in this thread to the interest in other topics, it becomes clear that this topic rates very high on the list for more people than do the other ones. I appreciate your very considerable efforts in keeping this topic alive and friendly; I take no credit for the occasional bits I have added. Thank you.

[Tigers2B1]

...The problem remains what good these studies do. They certainly do not produce any scientifically important data, but can create harm...

IQ results are used as part of the determination of who is subject to the death penalty and who isn't. IQ results are used as part of the determination of who qualifies for a position in "gifted" classes and who isn’t. And IQ results are used as part of the determination of which students require additional help and where that help is needed or will be most beneficial. Now the Supreme Court of the United States has just heard a case which may turn on the issue of whether evidence showing brain development and the parts of the brain used in decision making, as an individual matures, can be used to show that still developing brains lack the same level of impulse control as matured brains. These results will be considered on the issue of whether those under 18 years of age might be subject to the death penalty. During oral argument, the Supreme Court decision regarding the use of IQ in capital murder cases was mentioned.

[Roberth]

IQ results are used as part of the determination of who is subject to the death penalty and who isn't.

Do you see that as good or bad? I am not sure anymore on this board. This is a prime example for my statement. First, the death penalty should not be there in the first place. Second, whichever way they use the argument, they will soon also use it in the opposite way.

IQ results are used as part of the determination of who qualifies for a position in "gifted" classes and who isn’t.

Do you see that as good or bad? I see it as bad. It should be the academic achievement that counts whether your are in a school for more skilled persons or not. There are great examples around in the world.

Here are some that I know about. Grammar schools in Britain (unfortunately less and less these days); Gymnasium, HTL, HAK or equivalent in Germany, Austria and Switzerland; VWE in the Netherlands; they all work and do not produce 'freaks'. You know, there are also gifted children who are unhappy to be in "gifted" classes.

Regarding the beloved IQ on this board, I remember one study where they tested the IQ of the average Gymnasium pupil in Austria. It was something like 122 around 1982 and varied slightly between schools (I seem to remember 118 to 130).

Also, if you first go to a normal lower grade High School at the age of 10/11, you can still switch to one of these higher schools up to the age of 14/15 provided you have good marks (… and wish to go for higher education rather than going to a vocational school for three more years and end up as a very skilled plumber, for example. Not all high IQ children want to go into higer education). In all these schools you have to sit the equivalent of a British A-level which is your ticket to University. Even later you can still get into these higher schools education but you must take a private school path to get to the A-levels and equivalent.

The above are examples that show that you can create 'gifted' school environment in a very natural and healthy way. It is not a question of: >120 in, <119 out or whatever.

In these countries, you do not need an IQ test to get into higher education and are provided with several opportunities as long as your marks are fine. … and that is the way it should be!

And IQ results are used as part of the determination of which students require additional help and where that help is needed or will be most beneficial.

You do not need IQ tests for that. Simply help them and provide opportunities!

At the age of 14, I sat a 3 hour "carrer advice test" as part of the school that I went to. I remember the lady being quite uneasy with me since I had a rather wide variation within the test results. She pointed out that she could not understand a couple of unusually high non-correlations. For example, in one sector, I was the best out of 80 in that year, but in a very correlated field I was within the last 20. I explained to her that she should not worry about it, I had never been very interested in those parts where I did not do so well … and I could easily improve if I needed to.


Now the Supreme Court of the United States has just heard a case which may turn on the issue of whether evidence showing brain development and the parts of the brain used in decision making, as an individual matures, can be used to show that still developing brains lack the same level of impulse control as matured brains. These results will be considered on the issue of whether those under 18 years of age might be subject to the death penalty. During oral argument, the Supreme Court decision regarding the use of IQ in capital murder cases was mentioned.


There we go! Next time they will prove that a 10 year old, highly gifted murderer should be executed. These 4 or 5 year old Asian children with 'measured' IQs over 200 should be careful! If they steal a candy bar, they may be convicted to several years in jail.

I do not think that some of the psychometrics guys here who do not see the ethical problems really get it. Maybe if I use an alteration of Murphy's law, based on history, something will click (although I doubt it).

Scientists and other people with responsibility should always keep in mind:

"Anything that can be used to hurt humans WILL BE used to hurt humans!"

"Anything that can be used for the benefit of humans MAY BE used for the benefit of humans!"

RobertH

[Tigers2B1]

Roberth

IQ results are used as part of the determination of who is subject to the death penalty and who isn't.

Do you see that as good or bad? I am not sure anymore on this board. This is a prime example for my statement. First, the death penalty should not be there in the first place. Second, whichever way they use the argument, they will soon also use it in the opposite way.

The death penalty exists, whether good, bad, or indifferent. It exists and IQ results may play a role in certain capital punishment cases. In the Supreme Court decision, I think it was noted that the defendant had an IQ of 57.

On your other point --- I really don’t think you’re saying what you seem to be saying "…whichever way they use the argument, they will soon also use it in the opposite way" since it doesn't make sense IMHO.

IQ results are used as part of the determination of who qualifies for a position in "gifted" classes and who isn’t.

Do you see that as good or bad? I see it as bad. It should be the academic achievement that counts whether your are in a school for more skilled persons or not. There are great examples around in the world.

Academic achievement also counts – IQ results are not the sole determiner of which students are admitted to gifted classes and which are not. The spaces for gifted students are limited. IQ results are used as yet another indicator of potential, and IQ results are highly correlated with scholastic results --- that is, IQ results are a good predictor of school achievement.

Here are some that I know about. Grammar schools in Britain (unfortunately less and less these days); Gymnasium, HTL, HAK or equivalent in Germany, Austria and Switzerland; VWE in the Netherlands; they all work and do not produce 'freaks'. You know, there are also gifted children who are unhappy to be in "gifted" classes.

Again, I have no idea what you mean by producing "freaks" – so I can't comment.

On the other point – about not wanting to be in gifted classes. So? I my not understand your point. If they don't want to be there than they leave - their parents take them out. If the student doesn't want to be in an accelerated, challenging learning environment, his or her grades will reflect that soon enough and he or she will get their wish. There are other students willing to take their seat, I'm sure. BUt if a student performs, and if their parent wants that child in that accelerated environment - well, some kids don't want to be in school period. But a child doesn't make that sort of decision about their education, the State does and the parent does.

The above are examples that show that you can create 'gifted' school environment in a very natural and healthy way. It is not a question of: >120 in, <119 out or whatever.

What’s "natural and healthy" about >A in, <B out in it's own right? Anyway, as mentioned, the States that have gifted programs also use acedmeic achievement in addition to predicted acedemic potential. Colleges also use stand-ins for IQ tests when they use GRE test results when determining which candidates get into graduate school and which don’t – same with Law Schools’ use of the LSAT. Both tests also have a correlation with IQ results. In fact, one of the most widely used tests, the SAT, HAD a high correlation with IQ results and was almost universally used by colleges as one of their admission standards. That SAT – IQ correlation no longer exists after the SAT format was changed in response to political pressures during the 1990s.

And IQ results are used as part of the determination of which students require additional help and where that help is needed or will be most beneficial.

You do not need IQ tests for that. Simply help them and provide opportunities!

To say "Simply help them" skips a lot of the work that's actually done in figuring out HOW to help them. Under the Individuals with Disabilities in Education Act (IDEA) schools are required, by Federal law, to provide opportunities for students with disabilities to 'mainstream' – that is, allow these students the opportunity to go to schools with other, non-disabled children. When these disabilities may be cognitive, IQ tests, with their varied subparts are a tool, albeit one of the tools, used when drawing up the required Individualized Education Plans (IEP) for certain disabled students. For example, an 11 year old child who can be mainstreamed may have only problems with nummerical reasoning but no other problems. Providing special help to that child, in that area, with that specific problem from the beginning - will most likely result in a benefit to the child in that area and allow him to mainsteam with other students. Waiting for failure to occur not only means that you might never understand the underlying problem but may lead to lost time and possible affects on self-esteem for the child.

At the age of 14, I sat a 3 hour "carrer advice test" as part of the school that I went to. I remember the lady being quite uneasy with me since I had a rather wide variation within the test results. She pointed out that she could not understand a couple of unusually high non-correlations. For example, in one sector, I was the best out of 80 in that year, but in a very correlated field I was within the last 20. I explained to her that she should not worry about it, I had never been very interested in those parts where I did not do so well … and I could easily improve if I needed to.

That sounds like an achievement test – not an IQ test.

Now the Supreme Court of the United States has just heard a case which may turn on the issue of whether evidence showing brain development and the parts of the brain used in decision making, as an individual matures, can be used to show that still developing brains lack the same level of impulse control as matured brains. These results will be considered on the issue of whether those under 18 years of age might be subject to the death penalty. During oral argument, the Supreme Court decision regarding the use of IQ in capital murder cases was mentioned.


There we go! Next time they will prove that a 10 year old, highly gifted murderer should be executed. These 4 or 5 year old Asian children with 'measured' IQs over 200 should be careful! If they steal a candy bar, they may be convicted to several years in jail.

Robert – I believe you completely missed the point and what the Supreme Court is presently looking at. The evidence presented was that young, forming minds, may not have the same social inhibitions and controls that mature brains shown. It’s not a case about using IQ results to execute children. The case involving adults with IQs below 70 was mentioned during oral argument since the ability to form a certain mental state is a requirement of a finding of capital murder.

"Anything that can be used to hurt humans WILL BE used to hurt humans!"

"Anything that can be used for the benefit of humans MAY BE used for the benefit of humans!"

With due respect, following that logic we should just all burn the house, send the car over the cliff, and go naked.

[Roberth]

The death penalty exists, whether good, bad, or indifferent. It exists and IQ results may play a role in certain capital punishment cases. In the Supreme Court decision, I think it was noted that the defendant had an IQ of 57.

On your other point --- I really don’t think you’re saying what you seem to be saying "…whichever way they use the argument, they will soon also use it in the opposite way" since it doesn't make sense IMHO.

Maybe I was too fast here. The problem is the following:
If I understand you correctly now then the Supreme Court said: "We cannot kill that person because the defendant is not intelligent enough to have made a conscious decision or does not understand the boundaries of what is right or wrong."
Although in this case the IQ test is, of course, used for a good cause, the moment you use IQs to justify non-killing, you automatically open the gate that somebody could use it as a justification for killing. The real issue here is the death penalty, of course. If it did not exist then the issue would not rise.

Having said that, I agree with you that this is an example to the benefit of people (if I understood you correctly and as portrayed in my answer). However, see further comments below.

Academic achievement also counts – IQ results are not the sole determiner of which students are admitted to gifted classes and which are not. The spaces for gifted students are limited. IQ results are used as yet another indicator of potential, and IQ results are highly correlated with scholastic results --- that is, IQ results are a good predictor of school achievement.

I agree with you and would suggest that psychologists put forward a petition to the government to increase the seats for gifted children or change the school system.


Again, I have no idea what you mean by producing "freaks" – so I can't comment.

On the other point – about not wanting to be in gifted classes. So? I my not understand your point. If they don't want to be there than they leave - their parents take them out. If the student doesn't want to be in an accelerated, challenging learning environment, his or her grades will reflect that soon enough and he or she will get their wish. There are other students willing to take their seat, I'm sure. BUt if a student performs, and if their parent wants that child in that accelerated environment - well, some kids don't want to be in school period. But a child doesn't make that sort of decision about their education, the State does and the parent does.

Sounds all fine to me except one issue. I see some danger in that accelerating part. When children grow up they have to learn all aspects of what it means to be a well-rounded human being. If a highly gifted child achieves calculus level at the age of 12 it does not mean that the child has the overall mental ability of a normal, intelligent child that reaches it at the age of 17. The highly gifted 12 old child may have the academic ability in certain sectors to match that of the 17 year old one but has missed the emotional time to mature and develop the other aspects of personality. In those countries that I listed, there is no difference in the curriculum between a normal school and a grammar school up to the age of 14. The only difference is that the subjects are presented in a more challenging way, i.e. more difficult.

A 14 year old child with the academic achievement to go to university is a bit freaky. I feel rather sorry for them. They simply miss the whole development: being lazy in school, playing truant, enjoying real friendships, having a girlfriend or boyfriend, sneaking into discos, etc. I am convinced that it is detrimental to their psychological development.

There is such an obsession with Academic achievement. It is only a small aspect of life. If you ask me to give you an age limit then I would say 17 before they are allowed to college.

But anyway, I may have got too carried away on this point.

What’s "natural and healthy" about >A in, <B out in it's own right?

I think that you misunderstood this time. It is not healthy to simply use an IQ score (smaller 120 is no, larger 120 is yes) to allow entrance to certain schools.

Anyway, as mentioned, the States that have gifted programs also use academic achievement in addition to predicted acedemic potential. Colleges also use stand-ins for IQ tests when they use GRE test results when determining which candidates get into graduate school and which don’t – same with Law Schools’ use of the LSAT. Both tests also have a correlation with IQ results. In fact, one of the most widely used tests, the SAT, HAD a high correlation with IQ results and was almost universally used by colleges as one of their admission standards. That SAT – IQ correlation no longer exists after the SAT format was changed in response to political pressures during the 1990s.


Using IQ tests in addition to academic results can be an excellent idea! (Now you are surprised, hey?) However, only when used as a one way rule:

"If child does not fulfill academic requirement then give second chance via IQ test."



To say "Simply help them" skips a lot of the work that's actually done in figuring out HOW to help them. Under the Individuals with Disabilities in Education Act (IDEA) schools are required, by Federal law, to provide opportunities for students with disabilities to 'mainstream' – that is, allow these students the opportunity to go to schools with other, non-disabled children. When these disabilities may be cognitive, IQ tests, with their varied subparts are a tool, albeit one of the tools, used when drawing up the required Individualized Education Plans (IEP) for certain disabled students. For example, an 11 year old child who can be mainstreamed may have only problems with nummerical reasoning but no other problems. Providing special help to that child, in that area, with that specific problem from the beginning - will most likely result in a benefit to the child in that area and allow him to mainsteam with other students. Waiting for failure to occur not only means that you might never understand the underlying problem but may lead to lost time and possible affects on self-esteem for the child.

Sounds excellent to me.

I actually met a person like that once and almost did not employ him (as a future network engineer) because he was totally miserable in mental arithmetic. One of my supervisors, however, asked me to give him a chance since he had followed a particular type of school (similar to Steiner). I said then to the manager: "Ok, but he is your responsibility and trouble." We gave the guy a chance and he became one of the 'stars'.

That sounds like an achievement test – not an IQ test.

It was both.

Robert – I believe you completely missed the point and what the Supreme Court is presently looking at. The evidence presented was that young, forming minds, may not have the same social inhibitions and controls that mature brains shown. It’s not a case about using IQ results to execute children. The case involving adults with IQs below 70 was mentioned during oral argument since the ability to form a certain mental state is a requirement of a finding of capital murder.

These results will be considered on the issue of whether those under 18 years of age might be subject to the death penalty.

I do not understand. They currently kill people under the age of 18? … and the IQ tests are used to prove to them that the subjects were not yet responsible enough to be killed? ????...????

With due respect, following that logic we should just all burn the house, send the car over the cliff, and go naked.[/QUOTE]

No, following that logic you must be alert from the very beginning that damage will happen, even if you mean well. You must therefore concentrate on those areas where the likelihood that damage occurs is very small. Knowing that it will occur, you must also check that the damage itself will probably be small. Furthermore, the principle also entails that you avoid those areas where the damage is obvious from the very beginning. Race-related studies are in this last category.

Most of the examples that you listed look good to me. Congratulations and sorry if I misunderstood some of it.

However, the danger also lurks in them that they will be used in a destructive way, the other way round of what you apparantly like to achieve. The most depressing aspect of it is that several of the applications that you mentioned should not be necessary in the first place.

Roberth

[Tigers2B1]

Yes, crimes committed by 16 and 17 year olds can, under certain circumstances, be punished by death. BUT Note – I'm talking about two different cases. That may be why what I've posted is confusing. One case is Roper v. Simmons, which is the case dealing with brain activity and inhibitions ---- the other is Atkins v. Virginia, which is the case that talks about IQ and inhibitions. LINKED is an article from MSN.com that explains – and mentions BOTH (as did the Supreme Court)

…Today's oral argument in Roper v. Simmons asks whether the execution of people who were 16 or 17 years old when they committed their crimes constitutes "cruel and unusual punishment" under the Eighth Amendment. … Unlike much of the court's jurisprudence, this analysis does not require poring over texts or channeling Thomas Jefferson. Instead, the court is asked to blink directly into the bright light of science and current events to determine whether "evolving standards of decency" mandate a change in the notion of what is cruel and unusual….

… In 2002 the court voted 6-3 to ban the execution of the mentally retarded in Atkins v. Virginia, using the "evolving standards" test to find that most states no longer believed it acceptable to execute them and that the mentally retarded had diminished culpability for their crimes….

http://slate.msn.com/id/2108172/&&CM=SlateBox&CE=5&HL=Reckless

[Evo]

As you know, I started this successful thread on August 22nd. Since then, the discussion has been one of the most successful ever, attracting 232 posts and a whopping 3565 viewers (and growing). Obviously this topic is one that interests many participants.

We have seen a good number of very well informed people offer their comments and insight (none approaching yours though). Even the people who have presented comments that were not supportable or even those that have been churlish, have helped maintain lines of discussion and have thusly brought additional information to benefit all.

When we compare the high interest in this thread to the interest in other topics, it becomes clear that this topic rates very high on the list for more people than do the other ones. I appreciate your very considerable efforts in keeping this topic alive and friendly; I take no credit for the occasional bits I have added. Thank you.Just because everyone feels it necessary to make sure that people that come here know that what you are posting is wrong doesn't make this a "successful" thread. Is that really what you think? :rofl:

Go look at the crackpot threads, you will find that they have some of the highest views.