Controversies in Autism - Intelligence

Intelligence

The percentage of autistic individuals who also meet criteria for mental retardation has been reported as anywhere from 25% to 70%, a wide variation illustrating the difficulty of assessing autistic intelligence. For PDD-NOS the association with mental retardation is much weaker. One of the criteria for Asperger's syndrom is that there is no clinically significant delay in cognitive development; which means that no one with Asperger's syndrom can have mental retardation.

A 2007 study suggested that Raven's Progressive Matrices (RPM), a test of abstract reasoning, may be a better indicator of intelligence for autistic children than the more commonly used Wechsler Intelligence Scale for Children (WISC). Researchers suspected that the WISC relied too heavily on language to be an accurate measure of intelligence for autistic individuals. Their study revealed that the neurotypical children scored similarly on both tests, but the autistic children fared far better on the RPM than on the WISC. The RPM measures abstract, general and fluid reasoning, an ability autistic individuals have been presumed to lack. A 2008 study found a similar effect, but to a much lesser degree and only for individuals with IQs less than 85 on the Wechsler scales.