Abstract
Autism Spectrum Disorder (ASD) is a developmental disorder characterized by deficits in social-communication and interaction in addition to restricted and repetitive behaviour and interests (APA, 2013). Despite these deficits, a few studies have shown superior performance in various visual tasks, such as visual search (O'Riordan et at. 2001) and embedded figures (Shah and Frith 1983). It has been suggested that these atypicalities can be attributed to enhanced functioning of low-level perceptual processes (Mottron et al, 2006). In the present study we examined basic visual processing of spatial frequency (SF) as a potential source for enhanced perceptual functioning (EPF). We employed three experiments to asses three distinct aspects of SF perception: sensitivity, precision, and accuracy. In Experiment 1, using a 2-interval forced choice (2-IFC) detection paradigm, contrast sensitivity was measured at eight SFs (1-24 cpd). In Experiment 2, we assessed precision as a function of spatial frequency via a 2-IFC discrimination paradigm. In Experiment 3, accuracy of SF perception (i.e., veridical perception) was assessed via a method-of-adjustment paradigm. Finally, in Experiment 4 we implemented a search experiment that has reliably demonstrated superior performance in people with ASD in previous studies (Hessels et al. 2014; Kemner et al. 2008; O'Riordan et al. 2001) to explore possible associations between performance in our first three experiments, and performance in visual search. No evidence for enhanced perceptual functioning was found in any of our three experiments examining sensitivity, precision, or accuracy of SF perception in ASD (N=10) compared to age-, gender-, IQ-matched controls (N=16). In addition, results from the search experiment failed to replicate previous findings of superior performance in ASD. These findings are consistent with our previous research on visual orientation perception (Shafai et al. 2015) and suggest that enhanced low-level visual processing is not a source of EPF in autism spectrum disorder.
Meeting abstract presented at VSS 2018