A method for examining productivity of grammatical morphology in children with and without specific language impairment

Children with specific language impairment (SLI) show inconsistent use of grammatical morphology. Children who are developing language typically also show a period during which they produce grammatical morphemes inconsistently. Various theories claim that both young typically developing children and children with SLI achieve correct production through memorization of some inflected forms (M. Gopnik, 1997; M. Tomasello, 2000a, 2000b). Adapting a method introduced by C. Miller and L. Leonard (1998), the authors investigated the use of present tense third singular -s by 24 typically developing preschoolers and 36 preschoolers with SLI. Each group was divided into 2 mean length of utterance (MLU) levels. Group and individual data provided little evidence that memorization could explain the correct productions of the third singular morpheme for either children with SLI or typically developing children, and there was no difference between children with higher and lower MLUs.