Talk:General intelligence factor

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[edit] Factor Indeterminacy

This page is not discussing g'

There is a fundamental difference between g (as Spearman, who had coined the term, had defined it), and a first principal component (PC1) of a positive correlation matrix. Spearman's g was defined as a latent (implied) 1-dimensional variable which accounts for all correlations among any intelligence tests. His tetrad difference equation states a necessary condition for such a g to exist.

The important proviso for Spearman's claim that such a g qualifies as an "objective definition" of "intelligence", is that all correlation matrices of "intelligence tests" must satisfies this necessary condition, not just one or two, because they are all samples of a universe of tests subject to the same g. It is now generally acknowledged (and easily verified empirically) (Guttman, 1992; Schonemann, 1997; Kempthorne, 1997; Garnett, 1919) that this condition is routinely violated by all correlation matrices of reasonable size. Hence, such a g does not exist any more than odd numbers divisible by 4 exist.

I recommend that somebody address this problem. I can not understand why this page is called “General Intelligence factor” if it does not discuss g'? There is not even one reference to Charles Spearman (the inventor) or factor analysis! I suspect this page was put together by somebody with no technical experience what-so-ever. —Preceding unsigned comment added by 70.68.179.142 (talk • contribs)

If you are suggesting that Spearman's definition of g, the "tetrad difference equation," is not supported by correlation matrices, that's fine. However, if you mean that the g factor does not exist, you should probably state your case a little better. The existence of g is an empirical question. Is the question of "odd numbers divisible by 4" also an empirical question?


[edit] Neutrality

I think the preceding information (with appropriate citations) needs to be fleshed out and added to the article as a part of Challenges to g, perhaps with a subheading Factor indeterminacy. I have removed the neutrality template pending addition of this information to the article, or further discussion here. Ward3001 21:33, 2 September 2007 (UTC)

[edit] Channel capacity

The material on channel capacity seems distinctly out of place, or at least a disproportionate part of the article. It is not even technically g theory.

The article in general has little to recommend it. I propose the following structure to both point out shortcomings and recommend how they may be filled:

  • Introduction (what is g)
  • History (discovery of g by Spearman, development of the field, present-day understanding)
  • Mental testing and g (cognitive tests all reflect g and derive most of their validity from g)
  • Biological correlates of g
  • Challenges to g

By necessity, much of this material will overlap with Intelligence (trait). My point of view is that g-specific material should be located here (definition of g loading; crystallized and fluid g; importance of g in explaining cognitive ability test results), while intelligence-related findings (not restricted to g, though perhaps best explained by g) should be located at Intelligence (trait).

Thoughts? --DAD 00:52, 18 Dec 2004 (UTC)

I've rewritten the article based on your suggested headings, plus one for the social correlates of g. I'll try to remember to add references and things next time I'm flipping through my Jensen books. I'm not entirely sure what the best way to go about handling the overlap between here, Intelligence (trait), and IQ is. I'll have to give it a little more thought. Oh, and welcome to Wikipedia. It's nice to see another person with an interest in psychometrics. -- Schaefer 03:42, 18 Dec 2004 (UTC)

I really like what you've done. Thanks for the welcome. Looks like there's plenty for us to do. -- DAD 02:05, 19 Dec 2004 (UTC)

[edit] Broad-sense and narrow-sense heritability?

The article talks about the "broad-sense" and "narrow-sense" heritability of g. But these terms are not defined, and heritability contains no explanation of what the difference is. Can anyone with a knowledge of psychometrics clear this one up? grendel|khan 21:35, 2005 Mar 4 (UTC)

[edit] Whoa..."general factor"?

Please comment on why this page has been renamed "general factor." I cannot find any scholarly references that introduce g as "the general factor". I'm holding a review from Scientific American called "The General Intelligence Factor" (Gottfredson 1998), and that seems to me a far better (clearer and more accurate) title. --DAD 30 June 2005 16:42 (UTC)

Somebody on this talk page called it a "general factor" (see below :-) Uncle Ed July 6, 2005 02:58 (UTC)

[edit] Is it really real?

The factor was:

  1. identified
  2. defined

Choice #1 implies that it's real, and somebody discovered it. Choice #2 leaves it as a theory. Uncle Ed July 5, 2005 23:56 (UTC)

g -- that is, a single, dominant general factor underlying cognitive ability test scores -- was discovered by Spearman. As the Scientific American review points out, a general factor is not inevitable (or even necessarily likely). How "real" g is depends on whether you're an adherent of Gould and others who argue against g as a "reified thing", or most researchers, who regard g as an abstract quantity like energy and gravity. It's really an epistemological question. As the biological basis of g becomes clearer, it seems likely that g will be fragmented up into as many biological components as are necessary to describe it. --DAD T 6 July 2005 02:32 (UTC)
So I would answer identified, as we might say Newton identified the laws of motion. --Rikurzhen July 8, 2005 07:03 (UTC)

[edit] The factor and the theory

Would someone please make the article distinguish between the real, observed "general factor" (g) and the "g Theory" I keep hearing so much about. I made a stub article for Jensen's hard-to-get book, The g Factor, but I still don't get it, and that's embarrassing for me. I'm way over to the right (not politically, I mean on the bell curve), so why is this so hard for me? Uncle Ed July 6, 2005 03:02 (UTC)

Done. It's basically the same relationship the evolution has to "evolutionary theory". The latter is used to encompass the former routinely (much to the dismay of scientists, when various of the other kind of "way over to the right" people jump on it and say, "Aha! Theory!") --DAD T 6 July 2005 03:15 (UTC)
I'm glad we can maintain a light-hearted attitude toward this, and that we can cooperate even though I may have come across as a bit heavy-handed at first. I have no desire to impose my own POV on any of the articles. All I want is for the readers to know what (a) scientists did and do think about these matters; and (b) how opinion leaders in the lay public feel about it all.
We need to make the "science" accessible to the layman. We also need to distinguish between (1) what scientists know, (2) what some scientists suppose, and (3) all the other major opinions are.
For example, a mere 200 years ago, some writers opined that black slaves in the US were no more intelligent than apes, and I suppose they used they argument they can't even read to bolster this claim. (Check me if I'm wrong, this is off the top of my head.) But there was also a law against teaching slaves to read so abolitionists asserted that this was a circular argument.
I'm interested in the lingering effects of slavery and racism. Assuming (for the sake of argument) that all people are pretty much born with equal potential, how long would it take for an oppressed group to catch up with the others once the others start saying "we shouldn't oppress these guys any more"? One generation, two, or what?
And have you heard about the "blue eyes brown eyes" experiment? Or the anecdote about the teacher who confused locker numbers with IQ scores? I'm not trying to prove any points; just wondering aloud what ought to go in the articles. Let's work together on this, and also try to get ZM to cooperate, too. Uncle Ed July 6, 2005 11:06 (UTC)
I feel similarly about cooperation and making the science accessible. Regarding "known" versus "supposed," it's a rare hypothesis in science that's purely supposed. Almost all hypotheses have some base of support, and it is the size and quality of that base, not the hypothesis itself, that determines credibility. For example, it may be a hypothesis that genes significantly determine intelligence, but the results supporting that hypothesis are overwhelming; that's why the scientific consensus rests there. The hypothesis that specific racially segregating genes shape intelligence has varying bases of support, from small but suggestive (Cochran's analysis of Ashkenazim gene clusters) to circumstantial (Asian, Hispanic and Black groups). I hope our content reflects the degree of support attending particular hypotheses.
As you may have gathered, my approach, given the intense controversy, is to try to suppress my own thoughts and hypotheses, and attempt to avoid saying anything I can't back up with a citation. This applies to results, to hypotheses, and to characterizations of the consensus. WP favors that approach in general, and it helps keep the discussion focused on content, so I have tried to hold others to the same standards, with little success in certain cases. Still, I'll keep trying.
Regarding the "legacy of slavery" question, I don't know. Love to see some real results on this, as it's important.
Remind me about the blue-eyes/brown-eyes experiment?
Regarding ZM, I've tried almost every approach I can think of (kindness, browbeating, humor, taking him seriously, WP "law enforcement", walking the talk, losing it); nothing I've done, or anyone else has done, has had any noticeable (to me) effect on the quality of his contributions, with one exception: he's responded to direct disciplinary action, and removed "racist" and "Nazi" from his vocabulary. It's beyond exhausting. --DAD T 6 July 2005 17:55 (UTC)

Added to the article:

The phrase "g theory" refers to hypotheses and results regarding g 's biological nature, stability/malleability, relevance to real-world tasks, and other inquiries.

I'm wondering, will the present article have enough info regarding these hypotheses, et al., to warrant a second article called g theory? If not, we can just add another section or two to g. Uncle Ed July 7, 2005 14:54 (UTC)

"g theory" is not widely used enough to justify an article of its own. g is fine, and while its coverage of the hypotheses is still fairly sparse, expansion should go here. All the renaming activity has been, to my mind, exactly what was needed. --DAD T 7 July 2005 15:04 (UTC)

[edit] Finding versus proposal

Spearman found, or discovered, or noted, or identified, the influence of a general factor. He then proposed his model. The continued insistence by some editors that Spearman simply hypothesized or proposed the existence of a factor alters history: while he may have hypothesized it, he also found that it was true, and that was his major contribution. The article must reflect this. --DAD T 18:38, 14 July 2005 (UTC)

This entire article needs a major NPOV revision. Spearman and others believed that it was true, but that does not mean it necessarily is. This article fails to note the controversy inherent in these claims. Jokestress 18:51, 14 July 2005 (UTC)
The article now notes the controversy. The claim that belief, rather than empirical reality, can somehow insert a general factor into correlation matrices has no support of which I am aware; Cite your sources. Spearman's data showed a general factor regardless of what he believed, and he was the first to note (and develop a quantitative test, vanishing tetrad differences, for) a general factor. The g-based factor hierarchy is, as the article notes based on the APA's consensus statement, the most widely accepted model for cognitive abilities. Claims of NPOV must be accompanied by citations. --DAD T 01:24, 15 July 2005 (UTC)
From the same source you cite: "Some theorists regard it as misleading (Ceci, 1990). Moreover, as noted in Section 1, a wide range of human abilities, including many that seem to have intellectual components, are outside the domain of standard psychometric tests." [1]. And remember that we are talking only about consensus within a field of study, and one that has been known to be wrong once or twice before... When I have time, I will write up the various authors like Chris Brand, who exemplify the unvarnished sentiment behind this worldview. Jokestress 05:55, 15 July 2005 (UTC)
Yes, I (and the article) acknowledge the controversy; "some theorists" are outside the mainstream, as the quoted sentence says. Chris Brand (who I've just Googled) is an abuser of the science, not a scientist, and even the most hated actual scientists (Jensen, who I respect, and Rushton, who I'm still fairly ambivalent on) don't partake of Brand & ilk's venom. Even guilt by association should require someone to snuggle up to Brand, not the other way around. --DAD T 06:15, 15 July 2005 (UTC)
When I have some time, I will lay out the reasons why Brand's de-published "G Factor" book sums up the problems with the concept nicely (he is the most egregious abuser of the science; other "g factor" proponents are just more cagey), and I will add various criticisms of factor analysis by Goodall, etc. and more on Thurstone. Jokestress 07:06, 15 July 2005 (UTC)
Great. Incidentally, I've yet to see a critique of factor analysis that doesn't collapse before ever really getting off the ground. In its stripped-down form, it's PCA; what could be simpler? --DAD T 07:16, 15 July 2005 (UTC)

[edit] Biological correlates of g - size

"g correlates less strongly, but significantly, with overall body size." That's an unfortunate choice of phrasing given the example earlier in the article about measurement of body size. Is the assertion that g correlates with height? With cubital length? With body mass (are the obese more intelligent?)? --Nclean 25th of August 2006

I agree. Obese people often have larger heads, and probably larger brains- does this mean people who are more obese are more intelligent? I've never found that at all

[edit] Disambiguation Needed!

Can someone please disambiguate "G factor" as it can also refer to the G-factor in physics. I don't know how to do disambiguation, sorry. See also Talk:G_factor. Thanks! Rotiro 10:48, 14 December 2006 (UTC)

[edit] Widely accepted but controversial?

In the lead, it is stated that the g-factor is "widely accepted but controversial". Honestly, I haven't read the rest of the article yet, but that seems to contradict itself.--Niels Ø (noe) 11:06, 23 February 2007 (UTC)

[edit] Some of these studies

"Brain size has long been known to be correlated with g (Jensen, 1998). Recently, an MRI study on twins (Thompson et al., 2001) showed that frontal gray matter volume was highly significantly correlated with g and highly heritable. A related study has reported that the correlation between brain size (reported to have a heritability of 0.85) and g is 0.4, and that correlation is mediated entirely by genetic factors (Posthuma et al., 2002). g has been observed in mice as well as humans (Matzel et al., 2003)."

The references to these studies should be listed, and I'd like to comment on them- did anyone ever notice how the Thompson study, which found grey matter to be so "heavily determined by genetic factors" examined TWINS RAISED TOGETHER?

I'm sorry, but that's a disgusting, profound amount of intellectual dishonesty and ignorance. To measure the heritability of a trait, you have to have the twins SEPERATED- NOT RAISED TOGETHER. Yet this study took twins that lived their entire lives together, exposed to the same environmental influences, causing thier intellect and personality to develop along the same patterns... yet, they just grabbed some random twins, saw "how similar they were", completely ignoring the dynamics of heritability studies, and, in some huge media blitz, where the study was spread and reported in countries across and the globe and even put on the cover of Nature- fucking disgusting. How could a study with such inane criteria EVER make it through peer-review?

Um, dizygotic twins share 50% of their genetic code, while monozygotic twins share 100%. Thus, if certain sections of the brain are shared more strongly by monozygotic than dizygotic twins, that indicates those sections of the brain have some underlying heritable component to them. I'll grant that I haven't seen the Thomson study, but the fact that it has made it through peer review suggests that its authors know what they're doing; conversely, writing angry posts in all caps and punctuating them with profanity does little to help your case. Harkenbane (talk) 04:59, 12 March 2008 (UTC)

[edit] Flawed Reasoning

Yet no single measurement of a human body is obviously preferred to measure its "size" (although obviously the volume is).

This statement uses "obviously" twice, contradicting itself. This is unfortunate because the entire analogy/paragraph only makes sense if the parenthetical is false. I would just delete the paragraph outright, but perhaps someone has a better solution (or a better analogy). I'll change it to "(excluding the volume, admittedly)" so it isn't quite so blatantly idiotic. Thehotelambush 06:31, 26 May 2007 (UTC)

[edit] anonymous comment

This page fails to acknowledge that the Flynn effect is seen by many as causing significant damage to the value of "g", because it effects individual skills on IQ tests disproportionately. For example, there are huge IQ gains in Raven's and Similarities tests, but relatively small gains in learned skills such as Arithmetic. Someone please update the page to reflect that the Flynn effect serves to challenge the meaningfulness of "g." —Preceding unsigned comment added by 156.56.154.85 (talk) 22:54, 24 September 2007 (UTC)

I really don't think the Flynn Effect provides any challenge to the existence of g. Yes, the Flynn Effect has affected some tests more than others, but scores on any one subtest are still positively correlated with scores on all other subtests. Now, James Flynn may argue that the Flynn Effect somehow disproves g, and that might be worth adding to the controversy section, but only because he made that claim; I don't think that the claim itself has any weight. Harkenbane (talk) 04:46, 12 March 2008 (UTC)

[edit] Page Title

It might be useful to decide if you want to talk about the "General factor of psychometric intelligence," which has been exhaustively discussed in the technical literature, or a "General Intelligence factor" which I don't really know anything about. Most of this article is about the general factor of psychometric intelligence. The general factor is derived by performing hierarchical factor analyses on a correlation matrix of performance on mental ability tests. The process for determining it has been exhaustively described by Jensen (The g Factor). John B. Carroll (Structure of Cognitive Abilities) describes a complete algorithm for determining the common factor in such a matrix. Spearman called it g. By this, he meant that it was a general factor. He did not mean it was a factor of general intelligence. He used g, and contrasted it to s, which he described as a specific factor. This was his two factor theory. The modern understanding of g, typified by Jensen’s and Carroll’s description, is in terms of factor analysis. It is sometimes called the "g factor," or "Spearman's g" (in deference to Spearman). In other words, it is the "general factor" of cognitive ability - not a "General Intelligence Factor." —Preceding unsigned comment added by 24.60.239.250 (talk) 01:34, 20 October 2007 (UTC)