EXPRESSIONS OF ASYMMETRIES AND ANCHORING IN BIMANUAL COORDINATION

The present study examined the contributions of inherent and incidental dynamical resources, and manual asymmetries, to the dynamics of bimanual coordination. Eight right-handed female subjects performed rhythmic movements of both hands, in two modes of coordination (in-phase and anti-phase), in self-paced and frequency-scaled conditions. In the in-phase (frequency-scaled) condition subjects were required to synchronize each beat of a metronome with either maximum pronation or maximum supination. In the anti-phase (frequency-scaled) condition subjects were required to synchronise each beat of the metronome with either maximum excursion to the left or maximum excursion to the right. Phase transitions from the anti-phase mode to the in-phase mode were observed as pacing frequency was increased. Transition pathways and times to transition onsets were dependent upon whether points of maximum pronation or maximum supination of the left or of the right hand were coincident with the metronome signal. The pattern of coordination (in-phase) adopted following phase transitions was predominantly that in which each beat of the metronome was synchronized with points of maximum pronation. A preliminary model accounting for these data is presented.