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Spearman’s Hypothesis: Support from the Wechsler Intelligence Scale for Children, Third Edition

Harrison Kane and Christopher Brand

Published: 2008/09/01


‘Spearman’s hypothesis’ states that Black-White differences in intelligence are largely a function of the demand of a test on the general factor, Spearman’s g. The present study investigates Spearman’s hypothesis using the standardization sample of the Wechsler Intelligence Scale for Children, Third Edition (WISCIII, 1991). As additional comparison groups, data from two samples of children with sensory impairments were also analyzed. Findings support Spearman’s hypothesis as an account of average Black-White differences in subtest performance. Differences on WISC-III in the disabled samples were not significantly related to Spearman’s g despite these groups’ experience of deprivation. Thus, the deprivation hypothesis is not affirmed, while Spearman’s g gains further credibility as an explanation for observed racial differences on IQ-type tests.

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