Movement synchrony and familiarity in dyadic and four-person conversations.

This paper investigates movement synchrony between German-speaking participants in spontaneous verbal interaction. In contrast to previous work where interpersonal synchrony was mostly examined in two-person interactions, we studied both dyads (n = 49) and quartets (n = 25) of participants, yielding new insights into how bodily coordination emerges in multi-party settings. Drawing on Motion Energy Analysis as a widely recognized video-based method for motion capture, we computed synchrony using windowed cross-correlations, finding that movement synchrony was present in both dyadic and quartet conversations. Furthermore, we found correlational evidence that familiarity between participants contributes to movement synchrony in two-person interactions, as well as to the extent to which individuals synchronize with others in quartets. Additionally, participants' self-reported affectivity is related to their proclivity to synchronize with their dyadic partner. These findings demonstrate how individual and relationship-level factors shape movement synchrony in both dyadic and quartet informal interactions.