Comparison of cognitive deficits among autistic and retarded children on the Arthur Adaptation of the Leiter International Performance Scales.

Seven autistic, 7 mentally retarded, and 11 normal children were matched for mental age according to the Arthur Adaptation of the Leiter International Performance Scale (AALIPS). On the basis of two constructs, concrete discrimination and formal discrimination, all of the tasks in the AALIPS were grouped into two indices and six scales. Group comparisons were made on the indices and the scales. The results showed that (a) the performance of the autistic children was better than that of the other two groups on concrete discrimination tasks, (b) the performance of the autistic children was poorer than that of the other two groups on formal discrimination tasks, and (c) the quality of the autistic children's performance decreased as task requirements for formal discrimination increased. This pattern was not observed among the mentally retarded or normal children. A further analysis for sex showed significant main effects for sex on the formal discrimination tasks. The application of these results to test interpretation and future research is discussed.