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RESEARCH NOTE
Purpose: The authors describe the procedures used to explain an unexpected finding that adolescents with Down syndrome (DS) had a lower mean length of utterance (MLU) than typically developing (TD) children in interviews without picture support, but not in narratives supported by wordless picture books. They hypothesize that the picture support of the narrative context increased the MLU for the group with DS alone.
Method: Adolescents with DS (n = 14) and TD children (n = 14) matched for receptive syntax narrated picture storybooks and participated in interviews. Transcription reliability, intelligibility/fluency, grammatical errors, discourse and sampling contexts, and discourse characteristics were examined for their effects on MLU.
Results: The DS group showed a greater responsiveness to adult questions than the TD group; an alternate MLU without yes/no responses showed the same interaction of group and context as the original finding. An additional comparison of MLUs, obtained from narratives present in the interview and narratives elicited using picture books, showed that picture support in narrative increased MLUs only for the group with DS.
Conclusion: Picture support, rather than narrative context alone, increased MLUs for the group with DS. Clinical use of narratives and picture support in assessment and intervention with individuals with DS is discussed.
KEY WORDS: MLU, Down syndrome, language samples, child language disorders, language assessment
Down syndrome (DS) has been shown to have a specific behavioral phenotype in language that includes delays in expressive syntax, errors of grammatical morpheme omission and use, and deficits in intelligibility (Chapman & Hesketh, 2000; Miller, Leddy, & Leavitt, 1999). In individuals with DS, mean length of utterance (MLU) has typically been used as a measure of expressive language in conversational (Fowler, 1995) or narrative (Chapman, Seung, Schwartz, & Kay-Raining Bird, 1998) speech samples, which have been shown to differ in the opportunities for complex syntax that they provide (Abbeduto, Benson, Short, & Dolish, 1995; Chapman et al. 1998; Leadholm & Miller, 1992; Thordardottir, Chapman, & Wagner, 2002). MLU differences have been shown to correspond to differences in complex syntax use (Thordardottir et al., 2002). Variation among narrative contexts has received less study in the DS population, although MLU has been shown to be influenced by discourse contexts.
This research note first reports our comparison...