Learning the probability of immediate interactional cues: Children’s acquisition of the discourse marker un in Japanese
How do children learn to use discourse markers in conversational interactions? This study focused on a Japanese discourse marker un, typically used as a positive response for yes-no questions and as a backchannel, and tested our prediction that children first learn to use un to respond to questions and then use it as backchannels after interlocutors signal the continuation of their discourse. To this end, we built generalised linear models on the longitudinal conversation data from seven children aged between 1 and 5 years and their caregivers. Our model revealed that children not only increase the general probability of un to reach adults’ rates, but also learn to use un in response to yes-no questions as we predicted. Children also tend to produce un as a backchannel after the interlocutor’s final modal particle ne, which is typically used to set a common ground. Our results show that children gradually learn different interactional contexts for the use of un from local probabilistic coherence between turns in conversations.