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Jennifer Foss-Feig, Carissa Cascio, Kimberly Schauder, Duje Tadin; A substantial and unexpected enhancement of motion perception in children with autism spectrum disorders.. Journal of Vision 2012;12(9):1352. doi: 10.1167/12.9.1352.
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INTRODUCTION: Motion perception deficits in autism spectrum disorders (ASD) are well documented. For example, ASD observers show higher motion coherence thresholds and impaired processing of biological motion stimuli. ASD is also associated with impairments in contextual processing of sensory information. These two lines of research motivated us to investigate the effects of stimulus size on motion perception in ASD. Typical observers show a surprising decrease in motion visibility of large, high-contrast stimuli — a contextual modulation termed spatial suppression. METHODS: We measured motion discriminations for stimuli of different sizes (1°, 2.5° and 6°) in children with ASD (N=11) and typical development (N=14), matched for age and IQ. Stimuli (4Hz; 1cyc/°; 93% contrast) were presented foveally. Adaptive staircases were used to estimate duration thresholds. RESULTS: As expected, we found that thresholds increased with stimulus size (F(2,24)=77, p<.0001), a result indicating spatial suppression. The strength of spatial suppression, however, did not differ between typical and ASD children (F(2,24)=1, p=.38). The unexpected result was better-than-normal motion discrimination in ASD (F(1,24)=13.2, p=.001). Specifically, across three stimulus sizes, we found a consistent two-fold decrease in thresholds for ASD observers. CONCLUSION: Given current theoretical models of ASD, our results reveal two counterintuitive findings. We find no abnormalities in spatial contextual modulations, but find a substantial and surprising enhancement in motion perception. What is the explanation? Our stimuli and task differ in two key ways from most studies that found motion deficits in ASD. First, we used simple (first-order) and highly visible motion stimuli, while deficits are typically found for complex moving displays (Bertone et al., 2003). Second, we used duration threshold measurements, which are effectively a measure of how quickly the visual system accumulates task-relevant stimulus information (Gold & Shadlen, 2000). One hypothesis is that ASD is associated with efficient accumulation of low-level motion information.
Meeting abstract presented at VSS 2012
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