Action-perception coordination dynamics of whole-body rhythmic movement in stance: A comparison study of street dancers and non-dancers

This study investigated whether whole-body, rhythmic action-perception coordination in stance is organized in terms of dynamic principles. We observed whether phase transition and hysteresis occur during the execution of dancing movements. Nine skilled street dancers and 9 novice controls performed 2 types of rhythmic knee-bending movements to a metronome beat in the standing position. Participants performed down-on-the-beat (in which knee flexion coincides with the beat) and up-on-the-beat (in which knee extension coincides with the beat), which are both typical components of street dance. All participants were instructed not to intervene in the pattern change. The auditory stimulus beat rate increased or decreased between 60 and 220. beats per minute (bpm) in steps of 20. bpm. We calculated the phase angle of beat time that is superposed on knee movement trajectory on a phase plane. Under the up-on-the-beat condition, phase transition and hysteresis were observed. The bifurcation frequency at which phase transition occurred significantly differed between groups, indicating that dancers were able to perform up-on-the-beat at higher movement frequencies than non-dancers. This suggests that dynamical properties may differ between Dancers and Non-dancers. The present results provide additional evidence that whole-body action-perception pattern formation is governed by general and common dynamical principles.