Objectives: We sought to better understand the limits of the automatic, contour-dependent phase of perceptual completion by taxing IC processing in typical and ASD children. We hypothesized that differences in basic visual processing and/or the tendency of persons with ASDs to default to processing parts over wholes, might weaken the strength of the illusion or increase the processing requirements of binding, differences that would be made manifest in the amplitude or the latency of the well-characterized IC effect.
Methods: ERPs to IC stimuli were compared between typical and ASD children, in two age cohorts: 6-10 and 11-16, as well as in a normal healthy adult cohort. IC- inducing stimuli were presented at three retinal eccentricities (4, 7 and 10 degrees). IC-effect amplitudes and latencies were measured for each.
Results: Results from typical adults replicate Murray et al’s (2002) IC effect, and demonstrate indifference of either effect amplitude or peak latency to the manipulation of eccentricity. This pattern appears to be replicated in typically developing children and ASD children ages 11-16, however, preliminary analyses indicate a less robust IC-effect for the ASD younger cohort as a result of the parametric manipulation.
Conclusions: These data indicate that automatic completion of object contours is accomplished by older children with ASD in a comparable fashion to their typical counterparts. Our preliminary analyses of the data suggest that there might be a deficit in contour completion in the younger ASD group. However, additional analyses are required before strong conclusions can be drawn.
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See more of: Brain Structure & Function