Rocking together: dynamics of intentional and unintentional interpersonal coordination.

The current study investigated the interpersonal coordination that occurred between two people when sitting side-by-side in rocking chairs. In two experiments participant pairs rocked in chairs that had the same or different natural periods. By instructing pairs to coordinate their movements inphase or antiphase, Experiment 1 investigated whether the stable patterns of intentional interpersonal coordination were consistent with the dynamics of within person interlimb coordination. By instructing the participants to rock at their own preferred tempo, Experiment 2 investigated whether the rocking chair movements of visually coupled individuals would become unintentionally coordinated. The degree to which the participants fixated on the movements of their co-actor was also manipulated to examine whether visual focus modulates the strength of interpersonal coordination. As expected, the patterns of coordination observed in both experiments demonstrated that the intentional and unintentional interpersonal coordination of rocking chair movements is constrained by the self-organizing dynamics of a coupled oscillator system. The results of the visual focus manipulations indicate that the stability of a visual interpersonal coupling is mediated by attention and the degree to which an individual is able to detect information about a co-actor's movements.