Infants’ use of interpersonal asynchrony as a signal for third-party affiliation

Infants use social cues to form expectations about the social relationships of others. For example, they expect agents to approach helpful partners and avoid hindering partners. They expect individuals with shared food preferences to be affiliates and individuals with opposing food preferences to be nonaffiliates. Interpersonal synchrony and asynchrony are important signals that adults use to guide third-party understanding. Specifically, we expect synchronous partners to be higher in rapport than asynchronous partners. Here, using a within-subjects design, we investigated if 12- to 14-month-old infants ( n = 62) also use interpersonal synchrony and/or asynchrony to make sense of third-party social relationships. A violation of expectations paradigm adapted from Liberman and colleagues was used. Infant looking time was recorded while watching videos of two women. The women moved either synchronously or asynchronously during familiarization trials, and subsequently interacted either in a friendly way (waving) or an unfriendly way (turning away) on test trials. Results revealed that infants expected asynchronous partners to be nonaffiliates but showed no significant expectation for synchronous partners. These results suggest that infants use interpersonal movement to understand their social world from as early as 12 months of age.