Cross-Sectional Trajectories of Mental State Language Development in Children With Down Syndrome.

Purpose This article (a) examined the cross-sectional trajectories of mental state language use in children with Down syndrome (DS) and (b) identified developmental factors associated with its use. Method Forty children with DS aged 6-11 years generated stories from a wordless picture book and completed an assessment battery of other linguistic, cognitive, and social-emotional skills. Their narratives were coded for mental state language density (the proportion of utterances containing mental state references) and diversity (the number of different mental state terms used). Results The emergence of mental state language use during narrative storytelling was observed across the sample; 0%-24% of children's utterances included references to mental states, and a variety of mental state terms were produced. Cross-sectional developmental trajectory analysis revealed that expressive vocabulary and morphosyntax were significantly related to increased mental state language density and diversity. Nonverbal emotion knowledge was significantly related to greater diversity of mental state terms used. Age and nonverbal cognition were not significant factors. Conclusions This first in-depth, within-syndrome characterization of mental state language use by school-age children with DS provides an important next step for understanding mental state and narrative development in this population. By identifying skills associated with the development of mental state language, this study provides an avenue for future longitudinal research to determine causal relationships, ultimately informing intervention efforts.