Unique profile of visuo-perceptual skills in a genetic syndrome.

Williams syndrome (WS) and Down syndrome (DS) are genetic disorders with characteristic neuropsychological profiles. Subjects with WS show surface similarities to subjects with right hemisphere damage (RHD) in their relative preservation of linguistic skills, their poor visuo-constructive skills, and their hierarchical processing biases. Ten adolescents and young adults with WS and nine matched subjects with DS were administered a battery of visuospatial perceptual tasks to test whether the profile of performance in WS would resemble that in RHD. It was found instead that the WS subjects showed a distinctive clustering of skills, with particular preservation of facial discrimination, but impairment of other perceptual skills. Subjects with DS showed a more homogeneous profile. The WS profile may map onto the functional dichotomy between ventral and dorsal visual pathways in the cerebral cortex.