Patterns of early lexical and gestural development in children with Williams syndrome.

Abstract

This dissertation addressed the early gestural and lexical development of very young children with Williams syndrome (WS), as measured by the MacArthur-Bates Communicative Development Inventories (CDI, Fenson et al., 2007). Receptive vocabulary (RV), expressive vocabulary (EV), early gesture (EG), late gesture (LG), and total gesture (TG) abilities were considered. Findings from cross-sectional samples of 49 18-month-olds, 56 24-month-olds, and 55 30-month-olds indicated considerable variability within each age group, with almost all children evidencing significant delay as measured by the CDI norms. Strong concurrent correlations were found among RV, EV, EG, LG, and TG for each age group. Longitudinal analyses indicated strong and significant correlations between RV, EV, EG, LG, and TG at age 18 months and these same abilities at 30 months in 29 children. Strong and significant relations between age of acquisition of each of three deictic gestures (give, show, point) and EV at 48 months were found for 39 children. A series of regression analyses focused on the predictive value of deictic gestures at 24 months, EV at 24 months, and maternal level of education for vocabulary and intellectual abilities at age 4 years, as measured by standardized assessments, in 27 children. Maternal education, EV, and deictic gestures were significant predictors of receptive and expressive vocabulary. EV and deictic gestures were significant predictors of overall intellectual abilities and verbal abilities. EV was a significant predictor for nonverbal reasoning abilities, and deictic gestures were a significant predictor of spatial abilities. Theoretical and practical implications of these findings are discussed.