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Left global visual hemineglect in high Autism-spectrum Quotient (AQ) individuals
journal contributionposted on 2010-08-01, 00:00 authored by D Crewther, Melanie AshtonMelanie Ashton, A Kuang
Abstract This study explores the visual perceptual differences between individuals from a normal population (mean age 25 yr) showing high versus low Autism-spectrum Quotient (AQ). A perceptual rivalry stimulus - the diamond illusion, containing both global and local percepts was used to explore the effects of occluder contrast (that hide the vertices of the diamond) and peripheral viewing, in populations of high (n=23) and low (n=15) AQ. Additionally, multifocal nonlinear visual evoked potentials (VEP), achromatic (24% and 96% contrast) were used to test for the presence of underlying physiological differences in magno- and parvocellular function. Both groups showed an increase in the percentage of global perception with increasing contrast of the occluding stripes, however, no difference was found between AQ groups. A relative increase in global perception with increasing eccentricity of the stimulus from fixation was also seen in both groups. Remarkably, the high AQ group showed a significant reduction in global perception when the stimulus was presented in left hemifield, but not for presentation in right hemifield. This global perceptual hemineglect suggests the possibility of abnormal parietal function in individuals with high AQ. While VEPs were similar at low contrast between hiAQ and loAQ groups, at high contrast there appeared to be interference with normal processing particularly of the magnocellular second order kernel slice. Seven VEP parameters used in a discriminant analysis correctly classified high or low group membership in 95% of the participants.