Cranial Size and Intelligence Link

[Nereid]

Correlation coefficients of 0.44, 0.25, 0.15, & 0.479 are terrible and, to me, indicate no correlation at all. Maybe if the correlations were 0.7 or higher, then you would have something to talk about.

Plus, I have yet to hear about a reliable way to quantify IQ.

Health warning! health warning! statistics and damned lies are about to be discussed! Parental discretion is advised!

Here are two time series*:
57643
58206
58737
59266
59827
60353
60878
61435
61958
62479

7298.3
7624.1
8113.8
8586.7
9066.6
9629.4
10021.5
10338.2
10744.6
11472.6

Bill Gates, via XL, tells me that they are highly correlated (r²=0.9954), which is far, far better than 'cranial size' and _g_.

So, I have a very tight correlation - where to from here?

Just as with 'cranial size' and _g_, it seems to me one can only take the next step if one has a theory to test; otherwise, what is the intrinsic meaning of an r² that is very close to 1?

In the case of 'cranial size' and _g_, we have a physical measurement of a body part of one mammal (this is Biology, not General Physics or Chemistry), and an abstract concept with roots in psychology (to turn up the contrast, NOT neuroscience).

How does the correlation which is the subject of this thread relate to any theories in biology? AFAIKS, it doesn't; it's simply stamp collecting.

{Note to Monique and iansmith: can you please move thread to a more appropriate section of PF? 'Other Sciences', for example.}

*http://sunearth.gsfc.nasa.gov/eclipse/TYPE/pluto.html .

 

[Tigers2B1]

...joining Mensa is to me like saying : "I only consider intelligent people worthwhile talking with"

So I take it that you’re joining Mensa.

 

[Mandrake]

Tigers2B1 : joining Mensa is to me like saying : "I only consider intelligent people worthwhile talking with"

Few people socialize with others who have significantly different IQs. In an interview, Jensen put the range of compatability at around 20 points. Some of you may have known Grady Towers (murdered not too long ago). Grady authored a number of interesting pieces, but the best known of them is his THE OUTSIDERS.
http://www.prometheussociety.org/articles/Outsiders.html

I strongly recommend this article to anyone who is highly intelligent. Grady discusses a number of social problems that are associated with very high intelligence. Unfortunately, Grady knew these things from personal experience as well as academic training.

Various papers and textbooks on the subject of intelligence show correlations between spouses and point out that people at one end of the range of IQ distribution are very rarely in contact with those at the other end. I found this to be especially true, since I worked as a physicist. I actually thought that the people around me were just ordinary people. After about 2 decades, I took a job that was not about physics and was shocked at the level of intelligence of the new workers around me.

 

[humanino]

sorry

My concern is that, my own IQ is defined with a \pm 30 or more depending on so many factors ! This is from the several tests I have done, because I find it fun.

After reading [thread=35476]this thread[/thread], I realize the fact that I considered IQ tests as a game must explain the variations observed. I did some of those while discussing with buddies in the computer room at school, so maybe I did not pay attention enough. I apologize for spamming this forum with bad arguments

 

[humanino]

So I take it that you’re joining Mensa.

why that ? I choose not to after I saw what it is !

 

[humanino]

Few people socialize with others who have significantly different IQs. In an interview, Jensen put the range of compatability at around 20 points.

This must be wrong. I spend the weekend with two blond girls, man

EDIT : ok, I said I wanted to quit spamming this forum. You are probably right guys. I do not want to admit the initial fact that intelligence is objectively quantifiable. This is for philosophical reasons, as well as the fact that i am afraid of the use such a quantification could have.

I admit I must be wrong here. :shy:

 

[Mandrake]

In the case of 'cranial size' and _g_, we have a physical measurement of a body part of one mammal (this is Biology, not General Physics or Chemistry),

I previously provided you with referenced comments pertaining to brain volume measurements in rats. Here it is again:

Britt Anderson determined that the _G_ factor scores for rats correlates with brain weight at r= +.48.
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.

and an abstract concept with roots in psychology (to turn up the contrast, NOT neuroscience).

The concept is not abstract. The relationship between brain volume and intelligence has been studied in great detail, using a wide range of techniques. The cause of the relationship is not known, but we don't know why masses attract each other either. That does not mean that gravity is not worth studying.

There are good reasons to believe that the variance in brain volume is related to the degree of myelination and to the number of neurons [Packenberg and Gundersen (1997)] present (taking into account the appropriate brain regions for each). I think I have also pointed out that the lower mean female IQ [Sex Differences in Intelligence and Brain Size:A Developmental Theory. Richard Lynn INTELLIGENCE 27(1): 1-12] is predictable by brain volume measurements.

How does the correlation which is the subject of this thread relate to any theories in biology? AFAIKS, it doesn't; it's simply stamp collecting.

What parts of the brain do you feel are not related to biology?

 

[BlackVision]

To Nereid:

Do you have any researches from the mainstream journals such as Intelligence, Nature, etc that would contradict the cranial size & intelligence link confirmation already well documented in the mainstream journals.

Aside from comparison within humans. Do you believe there is a cranial size to intelligence correlation when comparing species to species?

In the course of human evolution, cranial sizes have grown remarkably in size. Do you believe intelligence of humans grew along with it?

 

[humanino]

BlackVision : I apologize to you for the personal attack I commited in the last thread. I just succeded to prove that french people are arrogant and noisy. I wanted those apologies to be displayed.

 

[BlackVision]

BlackVision : I apologize to you for the personal attack I commited in the last thread. I just succeded to prove that french people are arrogant and noisy. I wanted those apologies to be displayed.

No problem at all. I didn't even really notice. Others on this board are far worst.

 

[Nereid]

I previously provided you with referenced comments pertaining to brain volume measurements in rats. Here it is again:

Britt Anderson determined that the _G_ factor scores for rats correlates with brain weight at r= +.48.
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.

Yes, you did. And I asked you if you could assist readers to understand the extent to which biologists feel that psychometricians are significantly contributing to their understanding of mammalian physiology (should I post your response here too?)

The concept is not abstract. The relationship between brain volume and intelligence has been studied in great detail, using a wide range of techniques. The cause of the relationship is not known, but we don't know why masses attract each other either. That does not mean that gravity is not worth studying.

Nice try

Is this the same 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.

There are good reasons to believe that the variance in brain volume is related to the degree of myelination and to the number of neurons [Packenberg and Gundersen (1997)] present (taking into account the appropriate brain regions for each). I think I have also pointed out that the lower mean female IQ [Sex Differences in Intelligence and Brain Size:A Developmental Theory. Richard Lynn INTELLIGENCE 27(1): 1-12] is predictable by brain volume measurements.

Yes, and you also pointed out that Jensen doesn't agree with Lynn (as also mentioned by hitssquad). Do you know of any neuroscientists, or other biologists, who have studied the biological variance in the brains of Homo sap.?

What parts of the brain do you feel are not related to biology?

Indeed, all parts of the brain would seem to be related to biology, which is partly why I'm quite puzzled that there is, AFAIS, no biological theory of intelligence. Or, to turn up the contrast, that neuroscientists seem to be pretty cool on intelligence (and other objects of psychometricians' desire), cf their intense interest in language; and why two sub-disciplines within psychology don't even seem to acknowledge each others' existence (e.g. how many 'personality psychometricians' quote, or do concurrent research in, 'intelligence'?).

 

[Monique]

I just want to say that biology is very complex and relies on many variables. A slight correlation might have been found between cranial size and intelligence, but it warrants more detailed research whether the effect found is real or just a statistical fluke. When something is published, it doesn't mean it is true, it means it is up for scientific scrutiny.

Larger cranial volume is not the only factor determining intelligence, you can think of scenarios where larger cranial volume would be deleterious to intelligence: difficult childbirth (may lead to oxygen deprivation), or hydrocephalus (waterhead) for instance.

 

[Phobos]

...Bill Gates, via XL, tells me that they are highly correlated (r2=0.9954)...

Oh great, Nereid. You just proved that astrology works.

 

[Nereid]

Oh great, Nereid. You just proved that astrology works.

I can do better than that ... I can probably write a fairly succinct algorithm for how to find data sets which will likely have very high correlations among the variables. The Pluto RA/US GDP example took me all of 10 minutes to find and construct, and I deliberately chose it because no one (other than astrologers - I didn't think of that ) would be tempted to see something deep and meaningful in the clear correlation. It shouldn't be hard for any PF member to come up with some quite plausible-looking, highly correlated data sets, particularly with one or more variables that relate to humans, their group interactions, etc.

 

[BlackVision]

Health warning! health warning! statistics and damned lies are about to be discussed! Parental discretion is advised!

Here are two time series*:
57643
58206
58737
59266
59827
60353
60878
61435
61958
62479

7298.3
7624.1
8113.8
8586.7
9066.6
9629.4
10021.5
10338.2
10744.6
11472.6

Bill Gates, via XL, tells me that they are highly correlated (r²=0.9954), which is far, far better than 'cranial size' and _g_.

So, I have a very tight correlation - where to from here?

That is a rather poor analogy. Unless you can show that scientists are making up a brain to their own specifications and defining g however they want it and then comparing. But doing a random correlation comparison, which the cranial size to IQ is, you cannot manipulate it the way you did. It's not like the brain and IQ are the researchers own creation which is the case for yours.

Any thoughts to my earlier questions?

 

[humanino]

What other purpose could these studies serve at : is not this work a racist one ? I need nor measure my intelligence, neither other's one.

Measuring my penis when I was a teenager was more useful to me

__________________
I do not cancel my apologies, as suggested by a moderator.

 

[Evo]

As heated as these types of discussions get, we can lose our temper, but we should not make personal attacks. I've been guilty of doing the same thing, I've learned from my mistakes and I am a kinder, gentler Evo now. Humanino, don't retract your apology, we all need to show respect to each other, even if we disagree.

As for cranial size and IQ, I would say that it is one of many factors that may have some bearing on IQ. I guess what I don't understand is why anyone would care about how big someones head is. If head size was the main predictor of IQ, are we then supposed to judge people based on hat size instead of merit?

I have a couple of articles that I will post in a bit.

 

[Nereid]

Do you have any researches from the mainstream journals such as Intelligence, Nature, etc that would contradict the cranial size & intelligence link confirmation already well documented in the mainstream journals.

Let me re-post an earlier set of questions :

Does anyone know how many of the 'countless' mainstream studies into the relationship between 'cranial size' and _g_ were performed using pre-defined, rigourous double blind protocols?

For the MRI (etc) determination of the 'cranial size', how many studies used automated image processing software to produce unbiased measures of 'size' (presumably volume)?

When (age, gender) sub-groups are analysed, what variation has been found wrt the 'cranial size' / _g_ correlations?

http://www.mugu.com/cgi-bin/Upstream/People/Rushton/rushton-peters.html ?

In the course of human evolution, cranial sizes have grown remarkably in size. Do you believe intelligence of humans grew along with it?

What I believe or don't believe is hardly relevant; much more important is what you mean by 'intelligence' in this question, and how could you determine it for (say) the average Homo erectus? Or, if you hypothesise that intelligence is correlated with cranial volume, does this lead you to the conclusion that 'Neaderthal Man' (H. sapiens neandertalensis), and whales, had/have more 'intelligence' than Homo sap.?

 

[Mandrake]

Originally Posted by Mandrake
I previously provided you with referenced comments pertaining to brain volume measurements in rats. Here it is again:

Britt Anderson determined that the _G_ factor scores for rats correlates with brain weight at r= +.48.
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.

Yes, you did. And I asked you if you could assist readers to understand the extent to which biologists feel that psychometricians are significantly contributing to their understanding of mammalian physiology (should I post your response here too?)

If you like. I don't recall what I wrote.

There are good reasons to believe that the variance in brain volume is related to the degree of myelination and to the number of neurons [Packenberg and Gundersen (1997)] present (taking into account the appropriate brain regions for each). I think I have also pointed out that the lower mean female IQ [Sex Differences in Intelligence and Brain Size:A Developmental Theory. Richard Lynn INTELLIGENCE 27(1): 1-12] is predictable by brain volume measurements.

Yes, and you also pointed out that Jensen doesn't agree with Lynn (as also mentioned by hitssquad).

That was not the nature of your initial question.

I pointed out that Jensen claims that measurements of _g_ produce identical means for both sexes. Lynn points out that multiple data sets show lower mean IQ for females. IQ and _g_ are not identical. The presumption is that the lower IQ mean of females is due to significantly lower scores on a few group factors.

Do you know of any neuroscientists, or other biologists, who have studied the biological variance in the brains of Homo sap.?

At the ISIR conference in 2003, the following people all presented papers that related to brain neurology as it relates to _g_: . Richard Haier, Vivek Prabhakaran, Paul Thompson, Con Stough, Aljoscha Neubauer, and Rex Jung.

What parts of the brain do you feel are not related to biology?
Indeed, all parts of the brain would seem to be related to biology, which is partly why I'm quite puzzled that there is, AFAIS, no biological theory of intelligence.

I don't understand your observation. What do you think would constitute a biological theory of intelligence? How does that differ from existing models?

Or, to turn up the contrast, that neuroscientists seem to be pretty cool on intelligence

What? How did you reach THAT conclusion? I get the impression that you haven't taken the time to read the psychometric literature and that you have not read the gold standard textbook (The _g_ Factor). The entire Haier symposium at the ISIR conference was devoted to this topic. Cool? Huh?

(e.g. how many 'personality psychometricians' quote, or do concurrent research in, 'intelligence'?).

You have mentioned these people on several occasions. I am unaware of their names. Can you tell us who you have in mind? Where do they publish? What are the standard textbooks that they reference? What else can you tell us about them? Thank you.

 

[humanino]

I don't recall what I wrote.

How fast do you forget ? This is amazing !

 

[Mandrake]

I just want to say that biology is very complex and relies on many variables. A slight correlation might have been found between cranial size and intelligence, but it warrants more detailed research whether the effect found is real or just a statistical fluke. When something is published, it doesn't mean it is true, it means it is up for scientific scrutiny.

You appear to be unfamiliar with the very large quantity of journal papers that have addressed this subject. They have used a wide range of investigation techniques. The correlation that has been found is quite large and important in comparison with other findings that are accepted as important. You seem to want to dismiss this area of study by implying that it is a fluke or that it has not been seriously investigated. Is that correct? Have you really studied the literature on this topic?

Larger cranial volume is not the only factor determining intelligence,

There has not been a single assertion here that cranial volume is the only factor determining intelligence. I haven't even seen a comment that claims it determines anything. What has been said is that there is a signficant correlation between brain volume and intelligence. The finding is robust.

you can think of scenarios where larger cranial volume would be deleterious to intelligence: difficult childbirth (may lead to oxygen deprivation), or hydrocephalus (waterhead) for instance.

And if you did think of such a thing, would it invalidate the MRI measurements? Your comment also seems to imply that the larger brain volumes reported in the literature necessarily imply larger skull size at the time of birth. Is that your belief? Is it true that skull size at birth is proportional to brain volume in adulthood? Since the difference in brain volumes that accounts for the variance is relatively small in adults, why would you extrapolate that this would cause so much increase in size of the head in a baby that it would result in more difficult child birth? Can you give us some verifiable numbers to support your suggestion?

 

[hitssquad]

Biological correlates of g, including head size, brain size and more

As for cranial size and IQ, I would say that it is one of many factors

Jensen calls them biological correlates or physical correlates.

that may have some bearing on IQ.

• Chapter 6 Biological Correlates of g[/size]
  
  
  • The fact that psychometric g has many physical correlates proves that g is not just a methodological artifact of the content and formal characteristics of mental tests or of the mathematical properties of factor analysis, but is a biological phenomenon. The correlations of g with physical variables can be functional (causal), or genetically pleiotropic (two or more different phenotypic effects attributable to the same gene), or genetically correlated through cross-assortative mating on both traits, or the nongenetic result of both being affected by some environmental factor (e.g., nutrition). The physical characteristics correlated with g that are empirically best established are stature, head size, brain size, frequency of alpha brain waves, latency and amplitude of evoked brain potentials, rate of brain glucose metabolism, and general health.

(Arthur Jensen. The g Factor. p137.)

what I don't understand is why anyone would care about how big someones head is.

Inspirations for specific researches are usually explicated in the introduction sections of the corresponding research write-ups. Regarding Jensen's inspiration, he says:

• [Biological correlates prove] that g is not just an artifact of the way psychometric tests are constructed, nor is g a mere figment of the arcane mathematical machinations of factor analysis.

(Arthur Jensen. The g Factor. p138.)

what I don't understand is why anyone would care about how big someones head is.

Head size is a relatively-easy-to-measure proxy for total brain size. Total brain size, in turn, is a proxy for the sizes of the specific parts of the brain most associated with g. As we zero in on the parts of the brain most closely associated with g correlations between variance in volume and variance in g grow larger and larger, approaching unity.

• In frontal brain regions, a regionally specific linkage has
  previously been found39 between g and metabolic activity measured
  by positron emission tomography (PET), suggesting that
  general cognitive ability may in part derive from a specific
  frontal system important in controlling diverse forms of behavior.
  Frontal regions also show task-dependent activity in tests
  involving working (short-term) memory, divided and sustained
  attention, and response selection40. Genetic factors may therefore
  contribute to structural differences in the brain that are
  statistically linked with cognitive differences. This is especially
  noteworthy, as cognitive performance seems
  to be linked with brain structure in the very
  regions where structure is under greatest genetic
  control (Figs. 2 and 3). This emphasizes the
  pronounced contribution of genetic factors to
  structural and functional differences across individuals,
  as detected here in frontal brain regions.

(http://www.loni.ucla.edu/~thompson/thompson.html. nature neuroscience • volume 4 no 12 • december 2001 pp1253-1258.)

what I don't understand is why anyone would care about how big someones head is.

Jensen is an emeritus professor of educational psychology. For many years there was a question in Jensen's country, the United States, as to why the Blacks of the country were not achieving educationally, socially and professionally at the same levels as those of the Whites of the country. Being an educational psychologist, Jensen decided that the question lay within his professional realm of scientific inquiry and so he inquired into it. Jensen explains this in Miele 2002 (p113):

• Jensen: Well, there are two points here. First, the big question in education has long been conspicuous- why do Black children, on average, have quite markedly lower scholastic achievement...

For the educational psychologist, the presence or absence of biological correlates to the single most educational-predictive psychological construct (g) ever discovered is evidence that is important to the forming of hypotheses explanatory and predictive of group social outcome differences.

what I don't understand is why anyone would care about how big someones head is.

Inter-population differences in head size may constitute useful evidence for evolutionary theorists, including evolutionary psychologists:

• ... Because evolutionary psychology is a protoscience, a field which has some ... Besides a reduction in sexual dimorphism, hominid brain size increased dramatically ...
  
  portrays evolutionary psychology as a ... to studies of encephalization (the progressive increase in brain size relative to ...
  
  the Evolutionary Psychology paradigm. Deacon is focused on explaining the progressive increase in relative brain size in the hominid ...
  
  Cogprints - The evolutionary psychology of perfectionism: Reply to ... Keywords: Expertise, problem solving, human evolution, evolutionary psychology, IQ, brain size, cognitive skills,

 

[Monique]

You seem to want to dismiss this area of study by implying that it is a fluke or that it has not been seriously investigated.

Mine was a cautionary statement about biology.

 

[humanino]

I changed my mood in order to be more useful to the conversation.

Say I want to understand how intelligence emerge in an abstract manner. I would propose to use neural networks as a model for the brain. As you probably know, a neural network is a parallel architecture of cellular automata, each of them having several inputs and one output. Currently used neural networks are of course much simpler than an actual brain, with the output equal 0 or 1 calculated by comparing a weighted sum of the inputs to a reference level. However, the structure is the same. Each cell can be in several states, and the dynamics is governed by simple laws, the next state being a function of both the previous state and the inputs.

What you are proposing, is that intelligence emerging in this manner is merely due to the size of the lattice. As you said it yourselves :

Aside from comparison within humans. Do you believe there is a cranial size to intelligence correlation when comparing species to species?

In the course of human evolution, cranial sizes have grown remarkably in size. Do you believe intelligence of humans grew along with it?

This is very much trivial. Anybody expects the ability of a neural network to increase if one doubles the size of the lattice. In a mathematical analogy, take a polynomial and try to fit a set of points with it. If you double the order of the polynomial, you double the number of points which can be fitted. This is a poor analogy, since the combinatorics in the lattice are non-linear. However, it amounts to pretty much the same thing.

Consider other possibilities : use more complex signals, like a vector instead of just 0 or 1, that is several possible types of outputs. Let one output be sent to several different automata inputs. Allow for a dynamical structure of the lattice... That would be interesting.

I am no more questioning your intentions, which would result in endless debates. I am questioning the relevance of your results.

 

[BlackVision]

Let me re-post an earlier set of questions

This does not answer my question. This has never been peer reviewed nor do I expect it would ever appear in Intelligence.

I have no idea how one could objectively determine the 'intelligence' of another species!

Really? So you're stating one will have a difficult time determining which is more intelligence. Dolphins or flies. Wolves or salmon.

Perhaps you could help? For example, how does one measure the intelligence of Deinococcus radiodurans

Perhaps a little common sense.

What I believe or don't believe is hardly relevant; much more important is what you mean by 'intelligence' in this question, and how could you determine it for (say) the average Homo erectus?

Because there is actually a dispute that in the path of human evolution, intelligence has increased? That the enormous growth of cranial size in the path of human evolution has had no impact on the intelligence of humans? You're trying to make it as though there is a controversy in an area which does not have one.

Or, if you hypothesise that intelligence is correlated with cranial volume, does this lead you to the conclusion that 'Neaderthal Man' (H. sapiens neandertalensis), and whales, had/have more 'intelligence' than Homo sap.?

Neanderthals could of very well been more intelligent. It wasn't their lack of intelligent that caused them to be extinct. Modern homosapiens also came very close to extinction itself.

Whales. Now that was silly. I believe humans have a higher brain size after body size adjustments.

 

[Evo]

Neanderthals could of very well been more intelligent. It wasn't their lack of intelligent that caused them to be extinct. Modern homosapiens also came very close to extinction itself.

BV, it appears that you are not familiar with the skills the Neanderthals are known to have possessed. Archaeological digs of Neanderthal sites clearly show what they were capable of.

 

[BlackVision]

BV, it appears that you are not familiar with the skills the Neanderthals are known to have possessed. Archaeological digs of Neanderthal sites clearly show what they were capable of.

I am quite aware of the acheivements of the Neanderthals. They have made several advances but not near as far as modern homosapiens. But that does not necessarily portray them as less intelligent. Any more so than the fact that most technological advances coming out of Europe instantly qualifies them as the most intelligence race. I've read several theories to why Neanderthals did not make the advancements that homosapiens did. The main one being that Neanderthals did not travel long distances as often as homo sapiens sapiens did. Maybe partly due to their heavier limbs. This caused less interaction with other Neanderthals and less exchange of ideas than with Homo sapiens sapiens.

 

[Nereid]

Inter-population differences in head size may constitute useful evidence for evolutionary theorists, including evolutionary psychologists:

• ... Because evolutionary psychology is a protoscience, a field which has some ... Besides a reduction in sexual dimorphism, hominid brain size increased dramatically ...
  
  portrays evolutionary psychology as a ... to studies of encephalization (the progressive increase in brain size relative to ...
  
  the Evolutionary Psychology paradigm. Deacon is focused on explaining the progressive increase in relative brain size in the hominid ...
  
  Cogprints - The evolutionary psychology of perfectionism: Reply to ... Keywords: Expertise, problem solving, human evolution, evolutionary psychology, IQ, brain size, cognitive skills,

Thanks for some great reading hitssquad!

While I didn't see anything in the links I did follow in the huge list of google results that was consistent with your intro ("Inter-population differences in head size may constitute useful evidence for evolutionary theorists") - at least, not wrt amh, the work of people like http://www.liv.ac.uk/www/evolpsyc/rimd.htm looks fascinating (not for the mathematically challenged however, his group's modelling of how information flows through social networks doesn't seem to be your usual psychological fare). Some PF readers may know Dunbar from his popular "The Trouble with Science" book.

 

[Nereid]

You appear to be unfamiliar with the very large quantity of journal papers that have addressed this subject. They have used a wide range of investigation techniques. The correlation that has been found is quite large and important in comparison with other findings that are accepted as important.

If you have it handy, could you give us some idea of the range of the reported correlations?

For example, in recent days in PF we've seen head size, head circumference, cranial volume, brain volume on the one side; on the other IQ, intelligence, _g_ (and maybe more). As you and hitssquad have taken pains to tell us, the second group are NOT synonyms; similarly, neither are the first group.

Further, in another thread (in Social Science?) I recall you posted a list of 'brain factoids', which included correlations.

I'm particularly interested in what differences there are between what researchers in the field have found (e.g. two results on head size-IQ correlation, perhaps 0.23 and 0.32), and how much the results from early work - say 1960s or before - have had to be re-interpreted in light of more recent work.

 

[Mandrake]

If you have it handy, could you give us some idea of the range of the reported correlations?

I have no idea where one would find the range or reported values. The only parameter that matters is the actual correlation, based on the best presently available methodology. The usual numbers are around r = 0.40 to 0.43.

For example, in recent days in PF we've seen head size, head circumference, cranial volume, brain volume on the one side; on the other IQ, intelligence, _g_ (and maybe more). As you and hitssquad have taken pains to tell us, the second group are NOT synonyms; similarly, neither are the first group.

Proxies for brain size show the effect very well, but obviously include factors that disconnect the proxy from brain volume.

I'm particularly interested in what differences there are between what researchers in the field have found (e.g. two results on head size-IQ correlation, perhaps 0.23 and 0.32), and how much the results from early work - say 1960s or before - have had to be re-interpreted in light of more recent work.

You can easily compile a lot of information by using a search engine and the Internet. Aside from that, you might want to read some of the best psychometric textbooks.