Cognitive processing of children with Williams syndrome.

The Illinois Test of Psycholinguistic Abilities was administered to 22 children with Williams syndrome and to 22 children with non-specific development disabilities, matched for age, sex and global intelligence. Visual processing abilities significantly differentiated the two groups. The children with Williams syndrome had substantially more problems with visual reception, visual closure and visual memory tasks. They appeared to adhere more rigidly than controls to a global deployment of visual attention. Their visual processing difficulties were not related to the level of mental ability. Visual reception, closure and memory scores correctly classified 82 per cent of the children with Williams syndrome and 68 per cent of the controls. Instructional and remedial programs are needed for these children.