Proceedings of the Annual Meeting of the Cognitive Science Society

Infancy is the foundational period for learning from adults, and the dynamics of the social environment have long beenproposed as central to childrens development. Here we reveal a novel, naturalistic approach for studying live interactionsbetween infants and adults. Using functional near-infrared spectroscopy (fNIRS), we simultaneously and continuouslymeasured the brains of infants (9-15 months) and an adult while they communicated and played with each other in realtime. We found that time-locked neural synchrony within dyads was significantly greater when they interacted witheach other than with control individuals. In addition, we found that both infant and adult brains continuously trackedthe moment-to-moment fluctuations of mutual gaze and infant emotion with high temporal precision. This investigationmarks a new means of understanding how the brains and behaviors of infants both shape and reflect those of their caregiversduring real-life communication.