Performance of children with ASD on the WISC‐V ancillary index scales

Ancillary index scales provide assessment professionals the opportunity to conduct a more comprehensive interpretation of a student's performance on the Wechsler Intelligence Scales for Children, Fifth Edition (WISC‐V); however, little is known about the performance of children with autism spectrum disorder (ASD) on these scales. The ASD special group population from the standardization sample of the WISC‐V and their demographically matched controls were included in the study (total n = 124; mean age = 11.5 years). The results of a discriminant analysis revealed that the Auditory Working Memory Index, the Cognitive Proficiency Index, and the Full‐Scale IQ were the best at discriminating among the different groups suggesting that the various groups perform differently on these indexes. School psychologists should calculate all ancillary index scales to obtain the most comprehensive understanding of the cognitive strengths and weaknesses of a child with ASD. Key points Comprehensive assessment of the cognitive abilities of children with autism spectrum disorder is essential to understand their intellectual strengths and weaknesses. This includes administering supplemental subtests of the WISC‐V to calculate all the available ancillary index scores. When comparing children with ASD to their neurotypical peers, the Auditory Working Memory Index and Cognitive Processing Index accounted for the most group difference. These findings are consistent with historically reported weaknesses in processing speed and working memory for children with ASD.