7. Initial Interpersonal Attraction between Mixed-Sex Dyad and Movement Synchrony

Rhythmic synchronization phenomena in interpersonal communication are classified into two, based on its temporal aspect and behavioural form similarity aspect. We focus on the temporal aspect, movement synchrony, the gestalt-like perception of movement rhythmicity or coordination. With the aid of THEME, we aim to describe it based on statistical definition of objective behavioural data. Behavioural synchronization phenomena can also be conceptualised according to the number of actors involved in synchrony (selfsynchrony and interactional synchrony). In a waiting room situation, we unobtrusively videotaped initial interaction of unacquainted mixed-sex dyads, and investigated whether movement synchrony between a dyad related with the formation of interpersonal attraction. Participants’ behaviour in the first and last minutes of initial 10-minute interaction was coded frame by frame. Movement synchrony measures calculated from it related with a participant’s interest in the partner more strongly in the first minute than in the last minute. However, the relationships were mostly explained by the increase of movement frequency. A movement synchrony measure that remained to be a significant signal was the repetitiveness of behaviour time-sequences. A dyad with a male participant interested in the partner decreased the repetitiveness of movement synchrony in the first minute. On the other hand, a dyad with a female participant who reported frequent sexual approaches by male strangers showed increase in the repetitiveness of movement synchrony. It suggested that such behavioural characteristics of frequently approached women tend to be interpreted as a courtship-like signal by male strangers. Only among dyads with frequently picked up women, the increase of female self-synchrony patterns positively correlated with male interest in her, circumstantially supporting the explanation.