Little is known about the perceptual deficits associated with autism. This is surprising because the accurate perception of socially relevant information is a necessary first step in social behavior. People communicate vast amounts of rich social information, such as emotion and intention, through their actions. Given the importance of human action perception to social behavior, vision researchers have conducted numerous experiments to understand how the human visual system normally analyzes the bodily movements or actions of other people. This is done by simulating human movements using multiple points of light across a computer screen. This psychophysical measurement will be applied to individuals with high functioning autism (HFA) to determine how, and how well, adults with autism can differentiate patterns of individual points of light that mimic human movement. Significance: This proposal addresses the question of whether individuals with high functioning autism (HFA) are compromised in their ability to perceive human action. If individuals with HFA have difficulty perceiving the actions of other people, then this might account for aspects of their social deficits. Such a finding would indicate that significant changes are needed in our understanding, assessment, and treatment of HFA. The results of this study are complemented by the group at the University of Glasgow which will investigate neural activation during tasks which involve visual processing while observing biological stimuli.