Abstract reasoning in autism: a dissociation between concept formation and concept identification.

The concept identification and concept formation aspects of abstract reasoning were examined in 90 nonmentally retarded individuals with autism and 107 normal controls. It was hypothesized that pronounced deficits would be found on concept formation tests, whereas performance on concept identification tests would be relatively intact. There was a significant difference between individuals with autism and individuals from a matched control group on all abstract reasoning tasks, but, with the exception of the Wisconsin Card Sorting Test (R. K. Heaton et al., 1993), differences on concept identification tests were not clinically significant. Factor analyses showed that concept formation and concept identification tasks loaded on separate factors in the autism group but not in the control group. Stepwise discriminant function analyses revealed that 2 tests of concept formation correctly classified 78.4% of cases, whereas concept identification tasks did not pass the tolerance test.