15 School-aged high functioning children on the autistic spectrum were compared with a neurotypical cohort on the WISC-III and the KABC-II, to determine the impact of the relatively more strict timing criteria of the former test on the evaluation of nonverbal intelligence. Significant group effects, showing lower performance by the ASD group were found for three of the five sub-tests for the WISC but not for the KABC, peaks and troughs were more evident for the WISC, and the evaluation of intellectual level was also markedly lower for ASD children on the WISC-III as opposed to the KABC-II. The results are discussed in terms of how speed of processing can impact on how children with ASD are ‘matched’ against neurotypical samples.
