Cattell's investment theory of fluid g and crystallized g
selfAdjoint said:
I agree that nature and nurture are both important. If you look at the Gray-Thompson paper you will see that they adopt the fluid g, GF and crystalized g, GC formalism.
Actually, it is a Cattellism.
In this view the common cognitive factor g is composed of two parts,
No. Cattell's
investment theory (his theory of Gf/Gc) is incompatible with the existence of
g.
- ...Cattell and Horn prefer not to extract the third-order factor, or g, contrary to the practice of most factor analysts. The Cattell-Horn model of abilities, therefore, is called a truncated hierarchy. That is, it lacks the apex of the hierarchy of factors, which is g. Cattell has stated in italics 25 that "there can be no such thing as a categorical general factor" (p. 87 )...
At the time that only two factors, Gf and Gc, stood at the highest level of Cattell's "truncated" hierarchy, there was a valid reason not to extract a thirdorder g. The reason is not that g doesn't exist in the test battery, but that a thirdorder hierarchical g is mathematically indeterminate when there are no more than two second-order factors. That is, there is only one correlation (i.e., the correlation between the two second-order factors, e.g., Gf and Gc) and all that can be determined is the geometric mean of the these factors' g loadings, which is equal to the square root of the correlation between the two second-order factors. Although we can know the average of the two factors' g loadings, we can't know the exact g loading of each factor separately, and ipso facto we cannot properly calculate the g loadings of each of the tests in the battery or calculate the g factor scores of the subjects who took the tests.
Arthur Jensen.
The g Factor. p124.
one of which increases through childhood but becomes fixed at maturity and doesn't change afterward, except to decline in old age.
Fluid g peaks and starts declining somewhere in the late-teens to mid-twenties, except in persons who adopt comprehensive anti-senescence regimens.
The other component, is basically th result of environment and increases throughout life.
The phrase
result of environment makes no sense in this context, and using the word
environment to describe what Gf (
fluid g) is applied to in order to arrive at the accumulated knowledge of Gc (
crystallized g), after first using it in the same paragraph to refer to the environmental component of heredity, amounts to an instance of equivocation.
In heredity, variance in genetic code and variance in environment each, and only each, account for a portion of total variance in phenotype. In development of fluid g, theoretically, both of the environments, biological environment and intellectual environment, play roles. In development of crystallized g, theoretically, of the two aforementioned types of environment, only intellectual environment plays a role. Although both Gf and Gc are substantially heritable and to almost equal degrees, according to theory, the non-environment component of Gf is genetic and the non-environment component of Gc is Gf (such that you need Gf in order to get Gc, but Gc is what you would remember even if you lost your Gf - as in the case of growing old and still retaining your cagey smarts, if not your general mental ability at its former youthful level, as you noted selfAdjoint).