Left-hemisphere dysfunction in autism: What are we measuring?

This study sought to investigate the left hemisphere deficit hypothesis regarding autism. A group of 15 autistic youngsters between the ages of 8 and 13 years was compared with a group of 15 mentally retarded youngsters matched for age and IQ on a set of measures presumed to be sensitive to neuropsychological dysfunction. The results suggested that this sample of autistic youngsters is best characterized by bilateral neuropsychological involvement, affecting left-hemisphere functioning predominantly but not exclusively. The findings of this and other such studies seem to be somewhat determined by the varied samples and assessments employed in the research. The practice of selecting tests which presumably tap left or right cerebral functions is highly inferential, and warrants concern, particularly when assessing complex cognitive functioning in autistic individuals.