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Questions on _g_ and intelligence

  1. Aug 22, 2004 #1

    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.


    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.

    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????
  2. jcsd
  3. Aug 22, 2004 #2


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    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.
    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?
    same question as above.
    This is quite new to me! Last time I looked, the research was quite equivocal - some studies had positive results, some negative, some mixed.
    Would you please clarify this? IIRC, Jensen was quite explicit that his work had applicability only to the US.
    This is also new to me - has this work been done only in the US too?
    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?
  4. Aug 22, 2004 #3


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    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:

    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.

  5. Aug 22, 2004 #4
    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.
  6. Aug 22, 2004 #5
    Okay, here goes:

    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!

    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.

    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.

    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.

    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.

    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.
  7. Aug 22, 2004 #6
    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.
  8. Aug 22, 2004 #7
    You have never done such a thing. Although I'm sure you wish you had.
  9. Aug 22, 2004 #8
    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.
  10. Aug 22, 2004 #9


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    Yes, I posted counter opinions.

    BV, you've not answered many direct questions.
    Last edited: Aug 22, 2004
  11. Aug 22, 2004 #10
    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.
  12. Aug 23, 2004 #11


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    :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.
  13. Aug 23, 2004 #12
    What is g

    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."

    It is called The g Factor (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.
  14. Aug 23, 2004 #13


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    Mandrake's a bit confused on some things. :wink:
  15. Aug 23, 2004 #14
    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.
  16. Aug 23, 2004 #15
    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.
  17. Aug 23, 2004 #16


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    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? 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?
    Roughly speaking, what proportion of the papers are from scientists from economies of the developing world?
    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.
    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.

    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??
  18. Aug 23, 2004 #17


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    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.

  19. Aug 23, 2004 #18
    Psychometrics has been around for awhile

    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
  20. Aug 23, 2004 #19
    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).

    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.

    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.

    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.

    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.

    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.

    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.
    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.
  21. Aug 23, 2004 #20


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    Thanks 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?
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