Purpose: This study examined cross-sectional age-related trajectories of expressive language variables (syntactic complexity, lexical diversity, unintelligibility, dysfluency, and talkativeness) derived from a narrative language sampling procedure.
Method: Narrative samples were analyzed from 103 typically developing individuals, ages 4-21 years.
Results: Results showed that this procedure was effective for the entire age range, with participants producing an utterance on virtually every page of the wordless picture books used to prompt the narrative. Importantly, the cross-sectional trajectories for syntactic complexity and lexical diversity showed age-related increases through the age of 18 years, although measures of other dimensions of language showed different relationships with age.
Conclusions: These data inform developmental work and document the extent to which the narrative procedure can be used to characterize expressive language over a wide age range. This procedure has been proposed as an outcome measure for clinical trials and interventions involving individuals with intellectual and developmental disabilities. The present data document the developmental levels for which the procedure and metrics derived are appropriate.