Across human cultures children learn language through their interactions with caregivers and peers. These early interactions, whatever form they take, are the basis for children's linguistic development, and result in something we universally recognize as human language. Children's linguistic development depends on their simultaneous acquisition of language use skills, and here I present my work on one such skill: turn-taking. Turn-taking is a requisite skill for conversation that patterns similarly across cultures: interlocutors switch between one turn and the next in less than 200 ms on average. This quick timing in a back-and-forth turn structure forms a perfect framework for contingent action, allowing us to achieve fine-grained behavioral coordination and mutual estimations of common ground via rapid feedback and conversational repair. A turn-based framework is key to our interactive efficiency, but it also shapes children's language-learning environments. Children begin to take turns (of a sort) long before their first words, but their mastery of turn-timing is a protracted process during which their responses are significantly delayed in comparison to adults. In a series of studies focusing on the production and perception of speech by adults and children ages 1-6, I explored the development of turn-taking skill and its relation to linguistic development. I found that turn-timing is intimately linked to children's linguistic development. Both in their production and perception of conversational speech, children become sensitive to different types of exchanges as they acquire new linguistic knowledge. Advances in their syntactic and prosodic knowledge during development result in a non-linear trajectory of turn-timing over their first few years. I discuss the implications of this tight relationship between linguistic processing and turn-structure, both for language learning and predictive processing during adult online language comprehension. By focusing on a signature property of human conversation, the ultimate goal of this research is to better conceptualize how the fundamental principles of human interaction shape human language use and structure.

Language acquisition is complex. However, one thing that has been suggested to help learning is the way that information is distributed throughout language; co-occurrences among particular items (e.g., syllables and words) have been shown to help learners discover the words that a language contains and figure out how those words are used. Humans' ability to draw on this information--"statistical learning"--has been demonstrated across a broad range of studies. However, evidence from non-WEIRD (Western, Educated, Industrialized, Rich, and Democratic) societies is critically lacking, which limits theorizing on the universality of this skill. We extended work on statistical language learning to a new, non-WEIRD linguistic population: speakers of Yélî Dnye, who live on a remote island off mainland Papua New Guinea (Rossel Island). We performed a replication of an existing statistical learning study, training adults on an artificial language with statistically defined words, then examining what they had learnt using a two-alternative forced-choice test. Crucially, we implemented several key amendments to the original study to ensure the replication was suitable for remote field-site testing with speakers of Yélî Dnye. We made critical changes to the stimuli and materials (to test speakers of Yélî Dnye, rather than English), the instructions (we re-worked these significantly, and added practice tasks to optimize participants' understanding), and the study format (shifting from a lab-based to a portable tablet-based setup). We discuss the requirement for acute sensitivity to linguistic, cultural, and environmental factors when adapting studies to test new populations.