Learning disabilities and intelligence test results: a model based on a principal components analysis of the WISC-R.

The unrotated principal components analysis of the WISC-R normative data yields a bipolar factor 2 which corresponds to a verbal-non-verbal continuum of test material. A review of published WISC-R and WISC data from learning disabled (LD) children reveals that the amount of deficit shown by these children on any particular subtest is closely proportional to the degree of verbal content, as expressed by the factor 2 score coefficient of that subtest. This test-specific effect was found to be very much greater in LD boys than in LD girls.