2. A study of white and Negro children in a poor section of rural Virginia, done by M. Bruce in 1940. In order to eliminate the factor of social and economic differences, the author first administered a test of socio-economic status, and then paired off her subjects so that each member of a pair, one Negro child and one white child, had the same socio-economic score. Negro overlapping on three separate tests ranged between 15 per cent and 20 per cent.
3. A study by Dr. Shuey of white and Negro college students in New York, in 1942. Again, the Negro and white students were first given socio-economic tests in order to pair them off. The Negro overlap amounted to 18 per cent. Of this investigation, Dr. McGurk says: “Considering that this was a highly selected group of college students, such low overlapping is surprising. It does not lend credence to the belief that socio-economic factors are responsible for the Negro-white differences in psychological test performance.”
4. A study of white and Negro kindergarten children in Minneapolis, 1944, done by F. Brown. The test scores found a 31 per cent overlapping. (At very early ages, overlap always is greater because tests deal more with performance and with sensory-motor responses, and less with verbal skills).
5. A study by T. F. Rhoads and associates of white and Negro children at the age of three. This was a very detailed study, in which each of the subjects was clinically examined from birth until the time he was administered a psychological test. Socio-economic factors were reported to be generally equal for the entire group of subjects. The overlapping amounted to 30 per cent.
6. A study by McGurk himself of Negro and white high school seniors in Pennsylvania and New Jersey. Again, Negroes and whites were matched for social and economic status by pairing a white subject with each Negro subject so that both members of a pair were identical or equivalent for fourteen different socio-economic factors. These students then took a test composed half of “cultural questions,” and half of “non-cultural questions.” McGurk’s finding: “In spite of the equivalence of socio-economic factors, 29 per cent of the Negro subjects overlapped the average total score of the white subjects. This is almost identical with the overlapping reported in the Alpha and Beta tests of World War I. There is hardly any question about the socio-economic superiority of this 1951 group of Negroes when compared with the Negroes of World War I. Yet, relative to white subjects, the intervening improvements in social and economic opportunities of the Negroes had not improved their psychological test performance at all.”
In 1953, Dr. McGurk published an additional study in the Journal of Abnormal and Social Psychology, “On White and Negro Test Performance and Socio-Economic Factors.” Here he reclassified the subjects of his 1951 study, in order to compare the 25 per cent of each race who might be regarded as a “high group” and as a “low group” in terms of socio-economic factors. Rearrangement of the data made no difference. It became apparent that socio-economic factors had not made the two groups equally proficient in psychological tests. “The average score of the high Negro group was very much lower than the average score of the whites of equivalent socio-economic status. In terms of Negro overlap, only 18 per cent of these Negro children of excellent socio-economic background obtained test scores that equalled or exceeded the average white score.”
Assuming that the liberal social anthropologists are right in what they say, that social and economic forces are of paramount importance, McGurk comments, “There should have been no differences between Negroes and whites in any of these comparisons. As it actually turned out, the difference between Negroes and whites is much greater when both groups are of high socio-economic status than when the racial groups are of deprived socio-economic status.”
Further analysis of McGurk’s 1951 study in terms of the “cultural questions” and the “noncultural” questions totally disproved the notion that cultural questions on these intelligence tests unduly hold back the Negro in his performance. Taking the cultural questions alone, it was found that 24 per cent of the high Negro group overlapped the average scores of the high white group. On the noncultural questions, where it might have been expected that the Negroes would do better, they did worse: Barely one out of five of the high Negro group overlapped the high white group. Comparing the two low groups, McGurk found that the low Negro group actually had an insignificantly higher average score than the low white group on the cultural questions, with an overlap of about 55 per cent. On the noncultural questions, the average of the low white group was significantly greater than that of the low Negro group. There was an overlap of about 29 per cent.
McGurk has summed up his conclusions in this fashion:
Regardless of our emotional attachment to the school desegregation problem, certain facts must be faced. First, as far as psychological test performance is a measure of capacity for education, Negroes as a group do not possess as much of it as whites as a group. This has been demonstrated over and over.