WISC-R Full Scale Mean IQs for Both Black and White Children, Aged 6 through 15 and Having Difficulty in School
Differences in WISC-R Full Scale mean IQs by age for 931 lower-class English-speaking Southern children were reported. Black children and white children tended to have similar mean IQs at Age 6 (t = —0.55). By Age 9 the differences in mean IQ became distinct and increased with age. The mean IQ of the black children declined after Age 8 while the mean IQ of the white children remained about the same or increased after Age 8.