| This dissertation examined language use by children and adolescents with the genetic disorder, Williams Syndrome (WS), specifically examining how they use referential (determiners and pronouns) and other cohesive devices (tense and conjunctions) to develop narratives based on a storybook. The study also examined grammatical and lexical errors in narratives and conversations as well as the relationship between linguistic proficiency and chronological age, age of speech onset, and verbal IQ. WS children (n=18; CA=10;9; MA=7;6) were compared to typically developing mentally age (MA) matched children (n=18; CA=7;2, MA=7;7). A subset of the WS children (n=10; CA=9;8) was compared to chronologically age (CA) matched children (n=10; CA=9;4). The study found that WS children used referential and cohesive devices in narratives similarly to MA-matched children, but made more errors in tense and referential cohesion than CA-matched children. WS children's grammatical error rates in conversations and in narratives were not different from the MA-matched children, but were higher than the CA-matched group. For lexical errors, WS children showed no difference from the MA-matched group in conversations, but made more errors than the CA-matched group. Notably, WS children made more lexical errors than both the MA and CA-matched groups in their narratives. Correlations for the WS children showed that verbal IQ and chronological age were better predictors of linguistic performance than age of speech onset. Overall, these findings demonstrate that WS children's accurate use of grammar is delayed, but is following a normative developmental pattern. Their ability to tense, determiners, and pronouns for cohesion was also delayed and was related to the ability to coordinate the use of the structures throughout the narratives. The unexpected finding for lexical errors in narratives demonstrates that WS children have particular difficulties with naming, suggesting either problems with lexical access or lexical representations. |
