After consideration of the drawbacks of such psychometrically derived theories of cognitive abilities as those of Guttman, Cattell, and Guilford, appeal is made to E. B. Hunt's "distributive memory" model and A. Newell's concept of the "production system" as possible bases for developing an alternative theory. Such a theory of…

Cognitive differences between 987 LD children and 178 EH children in public schools on a psychoeducational assessment battery were studied, and differences in factor structure were investigated. Caution is suggested in interpreting the results of multivariate statistical analyses, which indicated heterogeneity in the matrices of LD and EH…