Electrophysiological Correlates of Visual Search in the Autism Spectrum

The thesis examines the neural basis of selective attention in those with high and low levels of self-reported autistic traits. Existing literature suggests that those with an autism spectrum condition (ASC) show atypical selective attention (e.g. Burack 1994), and this has been extended to those with high levels of autistic traits (Bayliss & Kritikos, 2011). The research presented in the thesis has, for the first time, examined the neural basis of spatial attention in those with high and low levels of autistic traits by measuring the ERP deflections associated with covert attention, target selection and distracter suppression (The N2pc, NT and PD). The results provide evidence of neural differences in spatial attention in those with high levels of autistic traits. Specifically, a larger N2pc suggests greater allocation of attentional resources, and a reduced PD indicates reduced distracter suppression in those with high levels of autistic traits. No group differences were found in the NT component, indicating that the neural mechanisms underpinning target selection do not differ between those with high and low levels of autistic traits. The findings support Remington’s suggestion of an enhanced perceptual capacity in ASC (Remington et al., 2009); which would result in the processing of normally irrelevant information. Recent work has extended the possibility of an enhanced perceptual capacity to those with high levels of autistic traits (Bayliss & Kritikos, 2011; Milne et al., 2013), and this is supported by the ERP findings reported in the thesis. The findings may be an important factor in explaining the overwhelming perceptual experience often reported by those on the autism spectrum.