Synchronized affect in shared experiences strengthens social connection

People structure their days to experience events with others. We gather to eat meals, watch TV, and attend concerts together. What constitutes a shared experience and how does it manifest in dyadic behavior? The present study investigates how shared experiences - measured through emotional, motoric, and cognitive alignment - promote social bonding. We recorded facial expressions of participants as they watched four episodes of a TV show for a total of four hours with another participant. After each episode, participants rated their impressions of each character and reported how connected they felt to their viewing partner. We found that participants displayed temporally and spatially synchronized emotional facial expressions and the amount of synchrony predicted perceived social connection between viewing partners. Dyads who shared similar impressions of characters also reported feeling more connected. We found that all three of these processes independently contributed to a latent factor of a shared experience that predicted social connection with temporal synchrony explaining the most variance. Our findings suggest that the development of interpersonal affiliations in shared experiences emerges from shared affective experiences comprised of multiple synchronous processes and demonstrate that these complex interpersonal processes can be studied in a holistic and unified framework leveraging naturalistic experimental designs.