Variability in the Visual Perception of Human Motion as a Function of the Observer’s Autistic Traits

Introduction As described throughout this book, typical observers exhibit remarkable sensitivity to the social information conveyed by the bodily movement of other people. While researchers have historically motivated their studies of the perception of human movement by asserting that successful social behavior depends on it (for review see Blake & Shiffrar, 2007), empirical evidence for this long-standing assumption has only recently been collected. Of course, typical individuals vary in their social skills. This natural variability provides an inroad into understanding the connection between social abilities and social perception. If successful social behavior relies upon the accurate perception of other people's movements, then individuals with deficits in social function might reveal atypical sensitivity to human action. The Autism Spectrum Autism is a pervasive developmental disorder defined by impairments in social function, communication and repetitive or stereotyped behaviors (see also Pelphrey chapter in this volume). Lack of social interest, or 'autistic aloneness', was noted as a defining feature of this disorder in the first diagnostic description (Eisenberg & Kanner, 1956). Because there is substantial heterogeneity in the diagnosis, it is referred to as autism spectrum disorder, or ASD. Currently, most researchers do not consider autism to be a dichotomous phenomenon. Rather, they posit that the autistic spectrum extends into the non-clinical population. This concept of the broad autism phenotype