Abstract
Quick, accurate biological motion perception is fundamental to our understanding of the visual social world. Recent evidence has suggested that people with autism may show a selective deficit in visual motion processing. If biological motion perception is impacted in this group, it could significantly contribute to their deficits in social cognition and reciprocity. We investigated coherent and biological motion processing deficits in those with autism, as compared to a matched control sample, employing both psychophysical and fMRI paradigms. Using the method of constant stimuli, we measured coherent motion, biological motion, and global form detection thresholds. Coherent motion was measured with random-dot displays where coherence was varied through a standard “random-walk” manipulation. Biological motion displays were point-light depictions of a person walking embedded in moving dot displays whose coherence was varied. Global form perception stimuli were static glass patterns whose coherence was varied based on the percentage of dots aligned along a global form. As a group, those with autism showed both higher coherent and biological motion thresholds while matching control group performance on the coherent form task. The autism group also showed reduced MT+, STS and parietal area activation during in-scanner versions of coherent and biological motion tasks while showing similar levels of activation in V1. Additionally, activation in MT+ and STS in control individuals steadily increased with increasing directional motion or biological motion coherence. No consistent relationship between psychophysical and neural responses was evident in data from the autism group. These results provide evidence for a selective impairment in psychophysical and neural processing of visual motion in individuals with autism.
This work was supported by a mentor-based pre-doctoral fellowship from Autism Speaks (SR).