Grammatical morphology in school-age children with and without language impairment: a discriminant function analysis.

Purpose: The purpose of this study was to test Bedore and Leonard's (1998) proposal that a verb morpheme composite may hold promise as a clinical marker for specific language impairment (SLI) in English speakers and serve as an accurate basis for the classification of children with and without SLI beyond the preschool level.

Method: The language transcripts of 50 school-age children with SLI (M(age) = 7;9 [years;months]) and 50 age-matched typically developing peers (M(age) = 7;9) were analyzed. Following the Bedore and Leonard (1998) procedure, 3 variables were measured: a finite verb morpheme composite, a noun morpheme composite, and mean length of utterance in morphemes (MLU(m)).

Results: Overall findings indicated that neither grammatical morpheme composite alone adequately discriminated the groups at this developmental level. However, combining the verb and noun grammatical morpheme composite measures with MLU(m) resulted in good discriminant accuracy in classifying subgroups of the youngest children with and without SLI in the school-age sample.

Conclusion: Verb morphology alone is not a useful clinical marker of SLI in school-age children. Potential explanations for these findings and ideas for future research are discussed.