PURPOSE: In this study, the authors examined the impact of sampling context on multiple aspects of expressive language in male participants with fragile X syndrome in comparison to male participants with Down syndrome or typical development. METHOD: Participants with fragile X syndrome ( n = 27), ages 10-17 years, were matched groupwise on nonverbal mental age to adolescents with Down syndrome ( n = 15) and typically developing 3- to 6-year-olds ( n = 15). Language sampling contexts were an interview-style conversation and narration of a wordless book, with scripted examiner behavior. Language was assessed in terms of amount of talk, mean length of communication unit (MLCU), lexical diversity, fluency, and intelligibility. RESULTS: Participants with fragile X syndrome had lower MLCU and lexical diversity than did participants with typical development. Participants with Down syndrome produced yet lower MLCU. A differential effect of context among those with fragile X syndrome, Down syndrome, and typical development emerged for the number of attempts per minute, MLCU, and fluency. For participants with fragile X syndrome, autism symptom severity related to the number of utterances produced in conversation. Aspects of examiner behavior related to participant performance. CONCLUSION: Sampling context characteristics should be considered when assessing expressive language in individuals with neurodevelopmental disabilities.
PURPOSE: In this study, the authors examined the impact of sampling context on multiple aspects of expressive language in male participants with fragile X syndrome in comparison to male participants with Down syndrome or typical development. METHOD:Participants with fragile X syndrome ( n = 27), ages 10-17 years, were matched groupwise on nonverbal mental age to adolescents with Down syndrome ( n = 15) and typically developing 3- to 6-year-olds ( n = 15). Language sampling contexts were an interview-style conversation and narration of a wordless book, with scripted examiner behavior. Language was assessed in terms of amount of talk, mean length of communication unit (MLCU), lexical diversity, fluency, and intelligibility. RESULTS:Participants with fragile X syndrome had lower MLCU and lexical diversity than did participants with typical development. Participants with Down syndrome produced yet lower MLCU. A differential effect of context among those with fragile X syndrome, Down syndrome, and typical development emerged for the number of attempts per minute, MLCU, and fluency. For participants with fragile X syndrome, autism symptom severity related to the number of utterances produced in conversation. Aspects of examiner behavior related to participant performance. CONCLUSION: Sampling context characteristics should be considered when assessing expressive language in individuals with neurodevelopmental disabilities.