The development of children’s ability to track and predict turn structure in conversation

• We analyzed spontaneous turn-transition prediction by children ages 1–6.
• Children and adults primarily make anticipatory gazes following questions.
• Two-year-olds already predict upcoming responses at rates greater than chance.
• We find no evidence that lexicosyntax is sufficient for children’s prediction.

Children begin developing turn-taking skills in infancy but take several years to fluidly integrate their growing knowledge of language into their turn-taking behavior. In two eye-tracking experiments, we measured children’s anticipatory gaze to upcoming responders while controlling linguistic cues to turn structure. In Experiment 1, we showed English and non-English conversations to English-speaking adults and children. In Experiment 2, we phonetically controlled lexicosyntactic and prosodic cues in English-only speech. Children spontaneously made anticipatory gaze switches by age two and continued improving through age six. In both experiments, children and adults made more anticipatory switches after hearing questions. Consistent with prior findings on adult turn prediction, prosodic information alone did not increase children’s anticipatory gaze shifts. But, unlike prior work with adults, lexical information alone was not sufficient either—children’s performance was best overall with lexicosyntax and prosody together. Our findings support an account in which turn tracking and turn prediction emerge in infancy and then gradually become integrated with children’s online linguistic processing.