Summary
An hierarchical factor solution was obtained on correlations among WISC and ITPA subtests for 110 reading disabled children. The ability hierarchy which included a general (g) factor, two subgeneral factors, and five primary factors was arranged in a manner congruent with Vernon's structural paradigm. The g-factor was defined by a moderate but distinct pattern of positive loadings from WISC and ITPA subtests. At the subgeneral level a verbal-educational factor was defined by verbal WISC and ITPA subtests, and a spatial-perceptual-mechanical factor was defined by WISC performance and ITPA visual subtests. Three primary factors—freedom from distractibility, verbal precision, and quasi-specific—were defined by WISC subtests. Two primary factors—automatic processes and representational processes—were defined by ITPA subtests.