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In my view the interesting part of IQ is not merely in its ability to predict human performance in areas where we expect intelligence to matter, but also in its

In my view the interesting part of IQ is not merely in its ability to predict human performance in areas where we expect intelligence to matter, but also in its underlying claim that there is even such a thing as a general intelligence (g), as opposed to bundles of domain-specific abilities.

pulisse 8y ago
Proponents of g don't claim that it's an alternative to domain-specific abilities. They claim that it exists in addition to domain-specific abilities, and is what explains the correlation between performance across domains. That is, people who do well on mathematical tests also tend do well on tests of verbal ability. The factor analytic model that yields g attempts to explain this by viewing mathematical ability as the combination of two factors: a domain-specific mathematical intelligence and a domain-agnostic general intelligence. A subject's performance on verbal tests would similarly be modeled as the product of their g and of a cognitive ability specific to verbal tasks. That a subject's performance on one type of test is partially predictive of their performance on the other type is then (according to this model) explained by the two cases sharing a single partial cause, g.
whoisnnamdi 8y ago
As another poster mentioned, don’t think that g is necessarily in opposition to bundles of domain-specific abilities. I see g as an attempt at dimensionalality reduction - can the essence of what is admittedly a complex phenomenon be boiled down to a single metric which, while clearly not complete, is at least directionally correct / helpful. g in some sense could simply be a low dimensional projection of these more complex bundles. Just theorizing here, not an expert
- iguy 8y ago
  It is exactly that: think of it as the first principal component, of some group of tests. Obviously this always exists. The argument is really about how big the 2nd component is -- if it were comparable, then talking about the 1st alone would be very misleading. And for a typical bundle of school-like topics (like math/english/biology exams) it's quite a long way down: IIRC a factor of 3 or 4? If the bundle of subjects is different, then the size and meaning of the components will vary. In the tests the army does to slot recruits into all sorts of roles, I think manual dexterity is one of the things they care about which is almost uncorrelated with g. Eyesight is I think one of the only things negatively correlated with g (and it's thought to be nurture: bookish kids spend too little time outdoors).

pulisse 8y ago

Proponents of g don't claim that it's an alternative to domain-specific abilities. They claim that it exists in addition to domain-specific abilities, and is what explains the correlation between performance across domains. That is, people who do well on mathematical tests also tend do well on tests of verbal ability. The factor analytic model that yields g attempts to explain this by viewing mathematical ability as the combination of two factors: a domain-specific mathematical intelligence and a domain-agnostic general intelligence. A subject's performance on verbal tests would similarly be modeled as the product of their g and of a cognitive ability specific to verbal tasks. That a subject's performance on one type of test is partially predictive of their performance on the other type is then (according to this model) explained by the two cases sharing a single partial cause, g.

whoisnnamdi 8y ago

As another poster mentioned, don’t think that g is necessarily in opposition to bundles of domain-specific abilities. I see g as an attempt at dimensionalality reduction - can the essence of what is admittedly a complex phenomenon be boiled down to a single metric which, while clearly not complete, is at least directionally correct / helpful. g in some sense could simply be a low dimensional projection of these more complex bundles. Just theorizing here, not an expert

iguy 8y ago
It is exactly that: think of it as the first principal component, of some group of tests. Obviously this always exists. The argument is really about how big the 2nd component is -- if it were comparable, then talking about the 1st alone would be very misleading. And for a typical bundle of school-like topics (like math/english/biology exams) it's quite a long way down: IIRC a factor of 3 or 4? If the bundle of subjects is different, then the size and meaning of the components will vary. In the tests the army does to slot recruits into all sorts of roles, I think manual dexterity is one of the things they care about which is almost uncorrelated with g. Eyesight is I think one of the only things negatively correlated with g (and it's thought to be nurture: bookish kids spend too little time outdoors).