To account for the highly variable size of the mean difference between representative samples of the white and black populations on various psychometric tests of cognitive performance, Spearman (1927) suggested the hypothesis that the relative size of the mean white-black difference (in standardized scores) on various mental tests is a direct function of the tests' different loadings on the general factor, psychometric g, the highest order common factor in all complex tests of cognitive ability. This hypothesis has been borne out by numerous studies based on conventional psychometric tests. The present studies, based on large groups of elementary schoolchildren, extend the test of Spearman's hypothesis to performance on reaction time variables in simple information-processing tasks intended to minimize intellectual and cultural content. The variables' g loadings were estimated by their correlations with Raven's Matrices. Spearman's hypothesis was borne out significantly and at least as strongly as in previous studies based on conventional psychometric tests.