Lexical verb diversity in children with Down syndrome.

The language transcripts of seven children with Down syndrome and seven typically developing children matched for comparable MLU levels were compared for several measures of lexical diversity. These measures were percentage of utterances containing lexical verbs, number of verb tokens produced, a mean number of verbs per utterance (MVU), number of verb types used, and number of mental state verbs used. The results of this study indicated that the children with Down syndrome produced lexical verbs as frequently as their normally developing counterparts. In contrast, the children with Down syndrome were found to produce a larger variety of lexical verbs. An examination of a subset of verbs indicated that both groups of children produced an equal number of mental state verbs. These results support previous findings that when compared to syntactic development, children with Down syndrome show a relative area of strength in expressive vocabulary.