Does imitation facilitate the acquisition of grammar? Evidence from a study of autistic, Down's syndrome and normal children.

This paper re-opens the question of whether imitation plays a significant role in the acquisition of grammar. Data for this study came from four samples of naturalistic mother-child speech taken over the course of one year from four autistic, four Down's syndrome and four normal children, covering a range of MLU stages. In general, autistic children used more formulaic language, including imitations, than Down's syndrome children, who in turn used more than the normal children. Comparisons of imitative and spontaneous corpora from the same transcripts were made using MLU and the Index of Productive Syntax. The main findings were that, with few exceptions, spontaneous speech utterances were longer, and contained more advanced grammatical construction than did the imitation utterances. These findings held across all three groups of subjects. We conclude that imitation does not facilitate grammatical development.