Findings from relevant research applying Piaget's theory to mental retardation, psychosis, and autism are reviewed. Many autistic individuals show an arrest in operative functions at the sensorimotor functions. The early arrest interferes with subsequent development of higher-level conceptual, symbolic, and social skills. (Author)

Jean Piaget's theories about children's cognitive development are applied to the evaluation of childhood psychosis. Problems with the testing of such children are described, and results of a research project that used the Piaget-inspired Uzgiris and Hunt Ordinal Scales of Psychological Development to assess autistic children's cognitive processes…