Individual differences in the production of word classes in eight specific language-impaired preschoolers

The production of word classes in eight 53-62-month-old specific language-impaired (SLI) children was described and compared with that of 30 normal 24-33-month-old children in the same play situation. SLI subjects and nonimpaired children were selected within specified mean length of utterance ranges (low MLU versus high MLU). Production of word classes by subjects was evaluated in order to determine (1) whether SLI children showed a similar or a different word-class profile among themselves and when compared with non-impaired children and (2) whether MLU related to word classes would be useful as a single clinical index in assessment of language acquisition. Results showed that scores of SLI children in production of word classes reflect important individual differences among subjects. In the high-MLU sample, all SLI children produced each word class relatively within the same range as the nonimpaired group. In the low-MLU sample two SLI children were very different in their word-class profile and individual differences were further confirmed by a discriminant function analysis. Correlations between MLU and word classes were significant in nonimpaired children for all variables except Questions and Onomatopoeia and were only significant in SLI children for Verbs, Prepositions, and Personal Pronouns. Such findings contribute support to the view that there is "deviant" pattern of language in SLI children and once again questions whether MLU is one of the best discriminating indicators to use in the clinical assessment of language organization.