title: Orientation perception in Williams Syndrome: discrimination and integration.
abstract: Williams Syndrome (WS) is a rare neurodevelopmental disorder, which stems from a genetic deletion on chromosome 7 and causes a profound weakness in visuospatial cognition. Our current study explores how orientation perception may contribute to the visuospatial deficits in WS. In Experiment 1, we found that WS individuals and normal 3-4 year olds had similar orientation discrimination thresholds and had similar prevalence of mirror-reversal errors for diagonal targets (+/-45 deg). In Experiment 2, we asked whether this immaturity in orientation discrimination would also be reflected in a task requiring integration of oriented elements. We found that sensitivities of WS individuals for detecting orientation-defined contours were higher than sensitivities of normal 3-4 year olds, and were not significantly different from sensitivities of normal adults. Together, these results suggest that orientation discrimination and orientation integration have different maturational trajectories in normal development and different susceptibilities to damage in WS. These may reflect largely separate visuospatial mechanisms.
authors.affiliation: Psychological and Brain Sciences, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 20874, USA. mcp@ski.org
authors.forename: Melanie
authors.initials: M
authors.lastname: Palomares
authors.forename: Barbara
authors.initials: B
authors.lastname: Landau
authors.forename: Howard
authors.initials: H
authors.lastname: Egeth
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D005556:Form Perception; D006801:Humans; D009949:Orientation; D010775:Photic Stimulation; D013647:Task Performance and Analysis; D014796:Visual Perception; D018980:Williams Syndrome / Q000523:psychology*; D055815:Young Adult