Vocabulary abilities of children with Williams syndrome: Strengths, weaknesses, and relation to visuospatial construction ability

Purpose: This project was designed to identify relative strengths and weaknesses in vocabulary ability for children with Williams syndrome (WS) and to demonstrate the importance of stringent matching criteria for cross-group comparisons. Method: Children with WS and typically developing (TD) children completed standardized assessments of intellectual and language ability. Children with WS also completed a visuospatial construction ability assessment. Results: Study 1: Concrete and relational vocabulary standard scores were significantly lower for 5- to 7-year-olds with WS than for TD children. Children with WS earned significantly higher standard scores for concrete than for relational vocabulary. When groups were stringently matched for relational vocabulary size, children with WS did not evidence a specific weakness in spatial vocabulary. Study 2: Standard scores for relational vocabulary were similar to those for visuospatial construction ability for 5- to 7-year-olds with WS. Study 3: Nine-to 11-year-olds with WS demonstrated very limited relational vocabulary ability; relational vocabulary ability at 5-7 years was highly correlated with later relational language ability. Conclusions: Concrete vocabulary is a relative strength for children with WS; relational vocabulary ability is very limited and is at about the level of visuospatial construction ability. Accurate determination of group comparison results depends on stringent group matching.