Growth of Language Skills in Preschool Children With Specific Language Impairment: Implications for Assessment and Intervention

Abstract

A retrospective longitudinal study of 9 preschool-aged children, all meeting the criteria for specific language impairment (SLI), was conducted. Language growth was documented while the children were between the ages of 3 and 5 years and enrolled in a language intervention program. Three language measures were obtained across this period, including mean length of utterance (MLU) in morphemes, lexical diversity (i.e., number of different words used per 50 utterances), and a finite verb morphology composite (i.e., percent correct production of regular past - ed , present third person singular - s , and both the copula and auxiliary forms of is , are , and am ) . These longitudinal data were compared with cross-sectional data from 99 normally developing children who resided in the same community. Age-based comparisons revealed that, for most children with SLI, lexical diversity approached normal levels by the second year of data collection, whereas the production of finite verb morphology continued to be significantly delayed. A second set of comparisons, in which the children with SLI were compared with younger controls matched for MLU, further accentuated the persistence of difficulties with finite verb morphology. Applications of these language growth measures to assessment and intervention are discussed.