Verbal and non-verbal teaching behaviours jointly shape adult learning in naturalistic conversation

Which verbal and non-verbal behaviours used by ‘teachers’ support adults’ learning of new information during everyday conversations? While we know a lot about how caregivers’ behaviours impact children’s learning, no previous research has addressed this question with adult learners in naturalistic contexts, despite its scientific and practical importance. We analysed 22 hours of naturalistic dyadic audiovisual conversation between teachers and learners, assessing which of the teachers’ verbal and non-verbal behaviours, and their combinations, impacted learning of unfamiliar objects’ names and semantic properties. We found that both verbal and non-verbal behaviours impacted learning, modulated by learner’s individual differences. While learning of names and semantic features was supported by different verbal factors, only meaningful gestures showed robust effects across the two outcome measures, underscoring the importance of these gestures in adult, in addition to child, learning. We thus provide the first snapshot of real-world adult learning, with implications for educational practice.