Proceedings of the Annual Meeting of the Cognitive Science Society

Language acquisition is shaped by infants' engagement in socially embedded, synchronized communicative interactions. At a neural level, this is instantiated as neural synchrony. Extant literature has focused on in-the-moment predictors of neural synchrony, yet little is known about how early language environments shape neural coordination across development. The present study investigated the joint and independent effects of language quantity (i.e., number of adult words) and interaction quality (i.e., caregiver-infant reciprocal exchanges) on neural synchrony. We used day-long audio recordings collected between 12-24 months to characterize speech in infants' everyday environment and examined effects on caregiver-infant neural synchrony during play at 24 months. We found that greater conversational turn-taking at 12 months significantly predicted neural synchrony at 24 months, suggesting that early reciprocal interaction may be central in shaping neural attunement over time. These findings suggest that early reciprocal language experiences may scaffold the development of caregiver–infant neural attunement.