No narrowing in mean Black–White IQ differences—Predicted by heritable g.

Abstract

Comments on the original article, "Intelligence: New findings and theoretical developments," by R. E. Nisbett, J. Aronson, C. Blair, W. Dickens, J. Flynn, D. F. Halpern, and E. Turkheimer (see record 2011-30298-001). The present authors assert Nisbett et al were incorrect when they claimed that between 1972 and 2002 there was a 5.5-point narrowing of the 15-point IQ gap between Blacks and Whites (p. 146). In doing so, they sidestepped Rushton and Jensen's (2006) objections to Dickens and Flynn's (2006) evidence and failed to include subsequent evidence. The present authors maintain that Nisbett et al failed to describe accurately how heritable g provides evidence of a significant genetic contribution to Black-White differences. The present authors claim Nisbett et al obscured the topic by invoking alleged age and social class interactions and adoption studies of very young children. Many twin and adoption studies have shown that by adolescence, there are equal heritabilities (about 50%) for Whites, Blacks, and East Asians (Hur, Shin, Jeong, & Han, 2006; Rushton & Jensen, 2010b). There is no evidence of any special cultural influence, such as extreme deprivation or being raised as a visible minority, that operates in one group and not in others.