Atypical visual evoked potentials in individuals with autistic spectrum disorder
There are reports of atypical visual perception in individuals with autistic spectrum disorder (ASD) yet the aetiology of this remains unknown. It is currently unclear at what stage atypical perception arises in autism, whether it is specific to certain classes of perceptual stimuli or whether it occurs in response to many types of visual stimuli. In this talk I will present data from a recent study which investigated perception in 20 individuals with ASD and 20 matched controls by measuring visual evoked potentials (VEPs) elicited by Gabor patches presented at a range of spatial frequencies. We found atypical cortical activity in ASD elicited by these stimuli. Specifically the components appeared more quickly in the participants with ASD and the amplitude of the C1 component was reduced. I will discuss the possibility that atypical perception in autism occurs at an early stage of processing, is evident following presentation of very simple visual stimuli, and reflects a low-level abnormality within the visual system.