Admixture studies discussed in Shuey (1966)

Shuey (1966) discussed 16 admixture studies. A copy of Shuey’s summary table can be found in the following PDF files: Shuey1, Shuey2, Shuey3, Shuey4.

I summarized the studies below:

Studies that showed a large advantage for those deemed more admixed: 7

Feguson (1919) found that lighter colored blacks scored 11 points above darker colored blacks in a sample from Camp Lee (N=657). Feguson (1919) found that lighter colored blacks scored 14 points above intermediate colored blacks who scored 6 points above darker colored blacks in a sample from Camp Lee (N=667). Feguson (1919) found that darker colored blacks scored 60% as well as lighter colored blacks in a sample from Camp Lee (N=344). Feguson (1919) found that darker colored blacks scored 80% as well as lighter colored blacks in a sample from Camp Lee (N=344).

Peterson and Lanier (1929) found that light colored blacks scored 10 points above dark colored blacks in a sample from Chicago (N=83). Correlation: .30. Peterson and Lanier (1929) found that light colored blacks scored 3 points above dark colored blacks in a sample for Nashville (N=83). Correlation: .18

Young (1929) found that lighter colored 9 and 10 year olds in Louisiana had scores 12 and 5 points, respectively, above their darker skinned peers (N=277).

Tanser (1939) found that mixed blooded black scored 7.3 points above full blooded blacks in Kent Country Ontario (N=54). Admixture was judged by reports of genealogy.

Tanser (1941) found that mixed blooded blacks, as judged by gemological reports, scored an average of 6 points above full blooded blacks in Kent County Ontario, though the ½ blooded Blacks scored below the 1/4 blooded blacks on two of the three assessments (N=204). (My average).

Codwell (1947) found, in a sample from Houston, a 5 point gap between blacks judged to be mostly African and blacks for which there was strong evidence of admixture. The scores of blacks judged to be intermediate in admixture fell in between those deemed to be more admixed and those deemed to be less admixed (N=480).

Grinder et al (1964) found that mixed blacks scored intermediate to lighter and darker colored blacks of the same social class in Jamaica (N=940).. .

Studies that showed a moderate to slight advantage for those deemed more admixed: 6

Herskovits (1926) found, in a sample from D.C, a .17 correlation between test scores and the judged white element and a -.14 correlation between test scores and the judged black element (N=115). Average of all correlations: .125.

Davenport (1928), in a study of Jamaican and Grand Cayman whites and coloreds, found that brown coloreds outscored black coloreds on 3 out of 5 tests. On one test they scored about the same, and on another they scored lower (N=200).

Klineberg (1928) found that less African looking blacks scored 2 points above more African looking blacks in New York (N=200). He commented that there is no correspondence between test results and judged admixture.

Klineberg (1928) found an average correlation of -.9 between three indexes of African ancestry — Nose width (-.06), Lip thickness (-.10), and skin color (-.12) — and test scores in a sample of West Virginians (N= 139).

Peterson and Lanier (1929) found an average correlation of -.5 between four indexes of African ancestry – Nose width (-.11), Lip thickness (.07), Ear height (-.15), and interpupillary span (.01) — in a sample of New Yorkers (N=75).

Bruce (1940) found that light colored blacks scored 4 points above dark colored blacks in a sample from rural Virginia (N=72).

Studies that showed no advantage for those deemed more admixed: 2

Strong (1913) found that darker colored black children had significantly lower rates of mental retardation than lighter colored black children in a sample from South Carolina. Medium colored blacks fell in between the lighter and darker colored blacks in rates of MR (N=122).

Based n-weighted averages, in Kock and Simmons (1926), light colored blacks scored 2 points higher than dark colored blacks, but dark colored blacks scored 1 point higher than intermediate colored blacks. (On 3 out of 4 assessments light colored blacks outscored dark colored blacks; on 2 out of 4 assessments intermediate colored blacks outscored dark colored blacks (N=1078).

Studies that were equivocal but tend to support an environmental hypothesis: 1

Jenkins (1940) found the 64 prodigious Blacks drawn from a group of 8,000 had approximately the same amount of white ancestry as a national sample detailed by Hershovits. Based on the data, however, both samples had an admixture rate above 30% which is above the national average (Loehlin et al, 1975) and both samples had average SESes above the national average (Mackenzie, 1984). (I discussed this study more elsewhere).

References

Shuey, 1996. The testing of Negro Intelligence.