Scaffolding Early Dialogue: A Unified Account of Response Contingency in Child-Caregiver Interaction.

Early verbal dialogue emerges during the second year of life, despite children's still-developing linguistic, pragmatic, and cognitive abilities. This raises a puzzle: how can young children produce contingent responses under the real-time demands of turn-taking? In this study, we articulate a unified scaffolding account and test whether three caregiver-side mechanisms help explain this early emergence: lexical specificity in initiating utterances, interactive routines that constrain next-intent selection, and short caregiver realizations that can serve as models for children's own intent expression. Using recently developed automatic annotation tools for communicative intents and response contingency, we investigated this question in large-scale naturalistic corpora of child-caregiver dialogue, spanning 40 corpora and involving more than 600 children across more than 2500 transcripts. Across corpora, each mechanism was associated with higher child contingency, and all three remained predictive in a joint model controlling for age, child utterance length, and frequency-based factors. These findings are consistent with the view that early dialogue participation is supported not only by children's emerging capacities, but also by caregivers' structuring of interaction in ways that reduce processing demands at multiple steps of response formation. More broadly, the results provide quantitative support for a scaffolding-based account of early dialogue emergence and help connect developmental evidence to broader theories of real-time communication.