Turkheimer study

In this subsection I will deal with the effects on IQ of socioeconomic class (the Turkheimer study), and in the next subsection with the Flynn Effect. These are two important new developments that concern individual IQ and need to be discussed in detail. This whole section is the first part of myth-debunking. The second part appears in the final chapter and deals with an array of other myths that are more general. 

The new socioeconomic evidence first appeared in 2003,34 in what has been called the Turkheimer study, named after the lead author of the article that reported the study s findings. What the study shows is that in poor families nearly all the variance in IQ is accounted for by a combination of fetal and other environments, and the contribution of genes to variance of IQ is close to zero. The result is almost the reverse in affluent families—nearly all the variance is accounted for by apparent heredity. 

The Turkheimer study discussed in chapter 10 pointed out that correlations between heredity or environment and IQ are dependent on socioeconomic class, with environment contributing nearly all the variance for the lower socioeconomic class.81 The study shows us that the contributions of heredity and environment to variance of IQ scores depend on the socioeconomic class of the population tested. The Flynn effect shows us that distributions of IQ scores are artifacts of test construction and depend on the generation tested. Both effects are of great importance for social policy. 

Pavese N, Gerhard A, Tai YF, Ho AK, Turkheimer F, Barker RA, Brooks DJ, Piccini P (2006) MicrogHal activation correlates with severity in Huntington s disease A clinical and PET study. Neurology 66 1638—1643. 

Turkheimer E 1991 Individual and group differences in adoption studies of IQ. Psychol Bull 110 392-405... 

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