The WHAT and WHEN of language input to children: Linguistic and temporal predictors of vocabulary in 3-year olds

The quantity, quality and complexity of language input are important for children’s language development. This study examined how the detailed timing of this input relates to children’s vocabulary at 3 years of age in 64 mother-child dyads (male = 28; female = 36; White = 69%, Black = 31%). Acoustical analysis of turn-taking in mother-child dialogue found that more consistently timed maternal responses (lower response latency variability) were associated (r = .42, p < .001) with higher vocabulary (PPVT-3) scores. In mothers with consistently timed responses, the complexity (MLU) of their child-directed speech significantly predicted (r = .53, p = .002) their children’s vocabulary. This suggests that predictably timed contingent maternal responses provide an important learning cue that supports language development beyond the content of language input itself.