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Woon Ju Park, Kimberly Schauder, Loisa Bennetto, Duje Tadin; Evidence for elevated internal noise in Autism Spectrum Disorder. Journal of Vision 2016;16(12):1125. doi: https://doi.org/10.1167/16.12.1125.
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© ARVO (1962-2015); The Authors (2016-present)
Atypical sensory processing in Autism Spectrum Disorder (ASD) is widely acknowledged, but the underlying mechanisms are not well understood. Sensory noise plays a critical role in perceptual processing efficiency, but its influence in sensory symptoms in ASD is not yet clear. Recent evidence showed increased inter-trial variability in neural responses to sensory stimuli in ASD (e.g., Dinstein et al., 2012), suggesting that sensory responses might be atypically noisy in ASD. Here, we investigated the link between internal noise and visual perception in ASD. Using an equivalent noise paradigm, we tested the hypothesis that increased internal noise in ASD will lead to impaired visual sensitivity. METHODS: Participants were 21 children with ASD (ages 9-16) and 20 matched typically developing (TD) controls. They performed an orientation discrimination task on foveally presented gratings (1.5° radius; orientation was either -45° or 45° from the vertical). Contrast thresholds were measured at 8 levels of external noise (0-21%). Stimulus presentation was controlled using the FAST toolbox (Vul et al., 2008) and results were fitted with Bayesian estimation. This yielded reliable estimates of the entire threshold-versus-noise function in only 480 trials per individual. The perceptual template model (Lu & Dosher, 2008) was used to evaluate the effect of internal noise. RESULTS: Relative to TD controls, children with ASD showed higher contrast thresholds at lower external noise levels. Similar thresholds were observed at high external noise levels. The model analysis revealed that the data are best explained by increased internal additive noise in ASD compared to TD. CONCLUSIONS: We show evidence that high internal noise in ASD may be an important factor limiting visual orientation processing of individuals with ASD. This finding further suggests that increased variability in sensory processing may be, at least in part, underlying the presence of atypical sensory symptoms in ASD.
Meeting abstract presented at VSS 2016
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