Journal Article

The psychophysics of visual motion and global form processing in autism

Kami Koldewyn, David Whitney and Susan M. Rivera

in Brain

Published on behalf of The Guarantors of Brain

Volume 133, issue 2, pages 599-610
Published in print February 2010 | ISSN: 0006-8950
Published online November 2009 | e-ISSN: 1460-2156 | DOI: http://dx.doi.org/10.1093/brain/awp272
The psychophysics of visual motion and global form processing in autism

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Several groups have recently reported that people with autism may suffer from a deficit in visual motion processing and proposed that these deficits may be related to a general dorsal stream dysfunction. In order to test the dorsal stream deficit hypothesis, we investigated coherent and biological motion perception as well as coherent form perception in a group of adolescents with autism and a group of age-matched typically developing controls. If the dorsal stream hypothesis were true, we would expect to document deficits in both coherent and biological motion processing in this group but find no deficit in coherent form perception. Using the method of constant stimuli and standard psychophysical analysis techniques, we measured thresholds for coherent motion, biological motion and coherent form. We found that adolescents with autism showed reduced sensitivity to both coherent and biological motion but performed as well as age-matched controls during coherent form perception. Correlations between intelligence quotient and task performance, however, appear to drive much of the group difference in coherent motion perception. Differences between groups on coherent motion perception did not remain significant when intelligence quotient was controlled for, but group differences in biological motion perception were more robust, remaining significant even when intelligence quotient differences were accounted for. Additionally, aspects of task performance on the biological motion perception task were related to autism symptomatology. These results do not support a general dorsal stream dysfunction in adolescents with autism but provide evidence of a more complex impairment in higher-level dynamic attentional processes.

Keywords: autism; visual motion; biological motion; coherent motion; dorsal stream

Journal Article.  8547 words.  Illustrated.

Subjects: Neurology ; Neuroscience

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