A comparison of measures for assessing the level and nature of intelligence in verbal children and adults with autism spectrum disorder

Previous work has suggested that the Raven's Progressive Matrices (RPM) are better suited for capturing the nature of intelligence for individuals with autism spectrum disorder (ASD) than the Wechsler scales. The RPM measures 'fluid intelligence', an area for which it has been argued that persons with ASD have a relative strength. Given that measures of intelligence are used for establishing clinical diagnoses, for making educational decisions, and for group-matching in research studies, continued examination of this contention is warranted. In the current study, verbal children with ASD performed moderately better on the RPM than on the Wechsler scales; children without ASD received higher percentile scores on the Wechsler than on the RPM. Adults with and without ASD received higher percentile scores on the Wechsler than the RPM. Results suggest that the RPM and Wechsler scales measure different aspects of cognitive abilities in verbal individuals with ASD. For the verbal children and adults with ASD in the current study, the RPM and Wechsler scales have unique contributions that must be considered in context when establishing a baseline of cognitive function. The results of this investigation highlight the importance of thoughtfully selecting appropriate measures of intelligence consistent with clinical, educational, and research purposes, especially for verbal children and adults with ASD.