Cognitive subtypes in developmentally disabled children: a pilot study.

Differential diagnoses within the pervasive developmental disorders have insufficient reliability, validity, and descriptive homogeneity within groups to be used as distinct categories for research purposes. This study reports the results of cognitive subtyping of 54 developmentally disabled children. Fifty-one were successfully categorized in a small number of groups, characterized by different strengths and weaknesses on verbal, performance, memory, and quantitative tests. About half of the children had the relatively good visuospatial performance expected on the basis of previous literature on autistic children; these children were not behaviorally more autistic than the others. Measures of internal validity are reported, as well as validation by cognitive and behavioral variables. These results tentatively suggest that such psychiatric manifestations as autistic aloofness and maintenance of sameness may be relatively independent of cognitive skill patterns.