title: Developmental trajectories for spatial frames of reference in Williams syndrome.
abstract: Williams syndrome (WS) is a genetic disorder associated with severe visuocognitive impairment. Individuals with WS also report difficulties with everyday wayfinding. To study the development of body-, environment-, and object-based spatial frames of reference in WS, we tested 45 children and adults with WS on a search task in which the participant and a spatial array are moved with respect to each other. Although individuals with WS showed a marked delay, like young controls they demonstrated independent, additive use of body- and environment-based frames of reference. Crucially, object-based (intrinsic) representations based on local landmarks within the array were only marginally used even by adults with WS, whereas in typical development these emerge at 5 years. Deficits in landmark use are consistent with wayfinding difficulties in WS, and may also contribute to problems with basic localization, since in typical development landmark-based representations supplement those based on the body and on self-motion. Difficulties with inhibition or mental rotation may be further components in the impaired ability to use the correct reference frame in WS.
authors.affiliation: Department of Psychology, University College London, UK. m.nardini@ucl.ac.uk
authors.forename: Marko
authors.initials: M
authors.lastname: Nardini
authors.forename: Janette
authors.initials: J
authors.lastname: Atkinson
authors.forename: Oliver
authors.initials: O
authors.lastname: Braddick
authors.forename: Neil
authors.initials: N
authors.lastname: Burgess
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D005260:Female; D005556:Form Perception; D006801:Humans; D008297:Male; D009039:Motion Perception; D010468:Perceptual Disorders / Q000175:diagnosis*; D013028:Space Perception; D014785:Vision, Ocular; D014796:Visual Perception; D018980:Williams Syndrome / Q000175:diagnosis / Q000523:psychology*