A central question in the study of language development is whether the speech of parents is fine-tuned to their children's language level. This question was addressed through a local contingency analysis that examined the relationship between adjacent child utterances and parental responses. This analysis was applied to 3 longitudinal corpora from the Child Language Data Exchange System (B. MacWhinney, 1991): Adam (2-5 years old; 65,336 utterances), Sarah (2-5 years old; 64,346 utterances), and Abe (2-5 years old; 40,656 utterances) for 3 different lexical classes (modal auxiliaries, pronouns, and nouns). Results provide support for a developmentally sensitive version of the fine-tuning hypothesis. A contingent relationship in the interactional patterns of parents and their children that changed as a function of lexical class and child age was discovered.
