The Level and Nature of Autistic Intelligence Revisited

Background: Owing to higher performance on the Raven’s Progressive Matrices (RPM) than on the Wechsler Intelligence Scales (WIS), it has recently been argued that intelligence is underestimated in autism. Objectives: This study sought to replicate and elaborate the findings on RPM versus WIS performance in autism. Methods: RPM and WIS IQs were studied in a clinical sample of N = 48 individuals with autism (36 males and 12 females) aged 7.5 to 28.3 years (M = 15.3; SD = 6.4). Results: Average RPM IQ was higher than WIS IQ, albeit to a much lesser degree than previously reported. While the discrepancy between tests was substantial for participants with WIS IQs < 70, it was negligible for those with IQs ≥ 70. Conclusions: Giving the importance of reliable multidimensional IQ estimates in autism, the WIS should continue to be regarded as the first choice IQ measure in high functioning individuals. Additional testing with the RPM might be indicated in the lower end of the spectrum.