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Outstanding Synthesis of Current Work on IQ,
This review is from: The g Factor: The Science of Mental Ability (Human Evolution, Behavior, and Intelligence) (Hardcover)
In a brilliant 40-year career that has earned him a place among the most frequently cited figures in contemporary psychology, Arthur Jensen has systematically researched and extended Charles Spearman's (1927) seminal concept of g, the general factor of intelligence. The g Factor is an awesome and monumental exposition of the case for the reality of g. It does not draw back from its most controversial conclusions -- that the average differences in IQ found between Blacks and Whites has a substantial hereditary component, and that this difference has important societal consequences. However, The g Factor is not about race, as such. The first five chapters deal with the intellectual history of the discovery of g and various models of how to conceptualize intelligence. Other chapters deal with the biological correlates of g (excluding race), its heritability, and its practical predictive power. The fact that psychometric g has many physical correlates proves that it is not just a methodological artifact. Among biological variables, g loads on heritability coefficients determined from twin studies and inbreeding depression scores calculated in children born from cousin-marriages. g is also related to brain size measured by Magnetic Resonance Imaging (MRI), brain evoked potentials, and intracellular brain pH levels. It (g) is a product of human evolution and is also found in non-human animals. Despite these caveats, The Bell Curve affair allows one to safely predict that The g Factor's coverage of race will strike many as of central importance. All the issues Jensen raised in 1969 are still with us today. Indeed, much of the opposition to IQ testing and heritability would probably disappear if it were not for the stubborn and unwelcome fact that, despite extensive well funded programs of intervention, the Black-White difference refuses to go quietly into the night. Chapter 11 of The g Factor fully documents that, on average, the American Black population scores below the White population by about 1.2 standard deviations, equivalent to 18 IQ points. (This magnitude of difference gives a median overlap of less than 15 percent, meaning that less than 15 percent of the Black population exceeds the White average of 50 percent). The difference between Blacks and Whites in average IQ scores has scarcely changed over the past 80 years (despite some claims that the gap is narrowing) and can be observed as early as three years of age. Controlling for overall socioeconomic level only reduces the mean difference by 4 IQ points. Chapter 12 presents Jensen's technical arguments for why he believes that race differences are about 50 percent heritable. He emphasizes the fact that it is precisely those components of intelligence tests that are most heritable and that most relate to brain size which most profoundly differentiate Blacks from Whites.
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Initial post: Feb 20, 2012 4:00:05 PM PST
[Deleted by the author on Feb 20, 2012 4:05:18 PM PST]
Posted on Feb 20, 2012 4:05:09 PM PST
Steve Savage says:
This is an excellent review. I have been a strong admirer of your work, Dr. Rushton, long before I purchased and read "Race, Evolution, and Behavior," and have referred to it frequently in discussions (more akin to knockdown drag-outs) on forums in which IQ differences among the races has been the subject. I am privileged to have defended your scholarship against the onslaughts of some very vicious ad hominem attacks, most of which insisted that I denounce your work, which I absolutely could not do given its very comprehensive and exhaustive nature.
Steve Savage "King of the Beasts"
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