“To support his claim, Nisbett sidesteps 7 studies that showed a large relation between indexes of white admixture and IQ — Feguson (1919), Peterson and Lanier (1929), Young (1929), Tanser (1939), Tanser (1941), Codwell (1947); Grinder et al (1964) –and 4 studies that showed a moderate to small relation –Davenport (1928), Klineberg (1928), Peterson and Lanier (1929), Bruce (1940). He draws attention, instead, to the low correlations found between indexes of admixture and IQ in 3 studies – Herskovits (1926), Peterson and Lanier (1929), and Klineberg (1928) — and argues that the low correlations stand as evidence against the genetic hypothesis….
In short, the findings of the three studies that Nisbett highlights provide no evidence against the genetic hypothesis; rather, they are consistent with it. Now, turning to the whole set, of the 16 studies predating 1965, 13 showed a positive relation between indexes of white admixture and IQ (7 large, 6 moderate to slight), 2 samples show no such relation, and 1 was equivocal. Of the 2 studies that showed no relation, in one — Kock and Simmons (1926) – light colored blacks nonetheless outscored darker colored backs. In all, the findings are not inconsistent with a partial genetic hypothesis.”