Discourse and the acquisition of grammatical morphemes.

Adult recasts of child utterances have been shown to be related in a general way to the child's acquisition of syntactic structures. The current study had two aims. The first aim was to determine which feature(s) of recasts (i.e. reformulation, expansion, topic continuation, or reply) was responsible for facilitating language acquisition by comparing them to other maternal discourse models that were systematically defined by these properties. The second aim was to investigate this relation more specifically by relating adult discourse models of specific grammatical morphemes to the child's acquisition of those same morphemes. Again, recasts were of particular interest. Twelve mother-child dyads were videorecorded during one hour of naturalistic interaction when the children were 1; 10 and 2; 4. Results indicated that maternal recasts of specific morphemes were related to the acquisition of those same grammatical morphemes during certain developmental periods, whereas other grammatical morphemes were facilitated by expansions and topic continuations. These results are discussed in terms of the processes responsible for these effects.