title: ERP abnormalities of illusory contour perception in Williams syndrome.
abstract: Williams syndrome is a genetic disorder in which visuo-spatial performance is poor. Theorists have claimed that the deficit lies in high-level processing, leaving low-level visual processes intact. We investigated this claim by examining an aspect of low-level processing, perceptual completion, i.e. the ability of this clinical group to perceive illusory Kanizsa squares. We then used event-related potentials to examine neural correlates of perceptual completion. While participants were able to perceive illusory contours, the neural correlates of this apparently normal perception were different from controls. Such differences in low-level visual processes may significantly impact on the development of higher-level visual processes. We conclude that, contrary to earlier claims, there is atypical neural processing during low-level visual perception in Williams syndrome.
authors.affiliation: Centre for Brain and Cognitive Development, School of Psychology, Birkbeck College, University of London, Malet Street, London WC1E 7HX.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Grice
authors.forename: Michelle De
authors.initials: MD
authors.lastname: Haan
authors.forename: Hanife
authors.initials: H
authors.lastname: Halit
authors.forename: Mark H
authors.initials: MH
authors.lastname: Johnson
authors.forename: Gergely
authors.initials: G
authors.lastname: Csibra
authors.forename: Julia
authors.initials: J
authors.lastname: Grant
authors.forename: Annette
authors.initials: A
authors.lastname: Karmiloff-Smith
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D016022:Case-Control Studies; D004192:Discrimination, Psychological; D004569:Electroencephalography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005260:Female; D005556:Form Perception; D006801:Humans; D007088:Illusions / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D009778:Occipital Lobe / Q000503:physiopathology; D010775:Photic Stimulation; D011897:Random Allocation; D011930:Reaction Time; D013702:Temporal Lobe / Q000503:physiopathology; D018980:Williams Syndrome / Q000503:physiopathology*