Abstract
People communicate vast amounts of social information through their movements. Typical adults demonstrate an impressive level of visual sensitivity to these movements. The accurate perception of such socially relevant information is a necessary first step in social behavior. Significant deficits in social behavior are characteristic of autism spectrum disorders (DSM-IV). This raises the question of whether impairments in visual sensitivity to human motion are associated with autism spectrum disorders. Children with autism are compromised in their ability to detect the presence of point-light displays of human motion (Blake et al., 2003). Here we ask whether such deficits also exist within the typical adult population. The Autism-Spectrum Quotient (AQ) measures the degree to which adults with normal intelligence present traits associated with the autistic spectrum (Baron-Cohen et al., 2001). By correlating performance on biological motion perception tasks with performance on the AQ, we assessed whether variations in visual sensitivity to human action are associated with the presence of autistic traits in typical adults with normal intelligence and language skills.
Participants were Rutgers University undergraduates. Point-light displays of a walking person and of a moving tractor were constructed from motion capture data. Following a blocked design, the unmasked point-light person or tractor was presented as coherent or scrambled. Participants reported whether or not they detected the presence of the person or tractor. All observers performed above chance. Overall, person detection was superior to tractor detection. Observers with low AQ scores (less autistic traits) better detected the person than the tractor. Observers with high AQ scores (more autistic traits) showed no significant difference in their ability to detect the person and tractor. Follow-up experiments with point-light masks and inverted displays yielded consistent results. These findings suggest that variations in autistic traits influence visual sensitivity to socially relevant movements in normal populations.