Abstract
Neuropsychological theories have traditionally attempted to provide a unifying account of the complex and diverse behavioural manifestations of autism in terms of their underlying psychological mechanisms and associated brain bases. This article reviews three competing neuropsychological theories of autism: the executive dysfunction hypothesis, the weak central coherence hypothesis, and the limbic system hypothesis. Each theory is evaluated critically with regard to the primary neuropsychological deficit hypothesized and the research findings that have been offered in support of it. In a concluding section, some of the metatheoretical assumptions informing attempts to identify a 'core' neuropsychological impairment in autism are outlined and questioned, and new approaches to a neuropsychological understanding of autism are suggested.