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ERP evidence of reduced perceptual filtering predicts superior visual search in individuals with high levels of autistic traits.

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Abstract A number of independent studies have demonstrated superior visual search in individuals with autism spectrum conditions (ASC). The current explanation for superior search in ASC rests predominantly on enhanced lower-level perceptual processing, with a corresponding anatomical locus in the visual cortex. Here I will present work in which visual search efficiency and EEG indices of perceptual and attentional processes involved in goal-driven perception were obtained from individuals with varying levels of self-reported autistic traits. Inline with others, we found that individuals with higher levels of autistic traits were more efficient visual searchers. We also found that one EEG variable – attention-based modulation of P3b amplitude – predicted 30% of the variance in visual search efficiency. This was also the only variable that was associated with level of autistic traits. Given that P3b is a relatively late-occurring ERP deflection, i.e. between 350 and 600 ms post stimulus onset, and is thought to be generated in the parietal cortex, these data suggest that the origin of enhanced visual search in those with ASC may stem from abnormality in attention-based mechanisms rather than low-level perceptual mechanisms.

Biography I obtained my undergraduate degree in Experimental Psychology from Oxford University 1998. I then worked as a research assistant for two years, initially with Jordan Grafman in the National Institute for Neurological Disorders and Stroke at the National Institutes of Health (Bethesda, USA ), and then with John Swettenham & Ruth Campbell at UCL , in collaboration with Kate Plaisted at Cambridge. After completing my PhD, which was supervised by John Swettenham & Ruth Campbell at UCL , I took up an ESRC post-doctoral fellowship with Olivier Pascalis at Sheffield University where I set up the Sheffield Autism Research Lab (ShARL). In the following year I was appointed as a lecturer at Sheffield where I continue to work. In 2007 I took a 12-month sabbatical at the Swartz Center for Computational Neuroscience (SCCN), UCSD . Here I worked with Scott Makeig to learn and develop advanced techniques for EEG data analysis. My primary research area is the study of perception and attention in autism and I use behavioural, psychophysical and EEG methods to address questions in this area.

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