PERFORMANCE ASYMMETRIES IN MULTIFREQUENCY COORDINATION

Multifrequency bimanual coordination was examined within a paradigm of rhythmic movement. The goal of the present study was to characterize the intrinsic dynamics of bimanual systems categorized under predefined hand and frequency assignments. Performance asymmetries were anticipated between conditions of hand and frequency assignment. It was hypothesized that these phenomena, often regarded as a feature of attentional limitations, could be characterized at the level of the collective variable, relative phase. Four right-handed subjects completed tasks of rhythmic forearm movements under self-paced and frequency scaling conditions in which one hand would oscillate at twice the frequency of the other. Contrasting conditions in which the left hand versus the right hand adopted the faster frequency, the 'left-hand-fast' system demonstrated greater instability in measures of relative phase variability, time-to-transition, and phase attraction. However, the individual limbs did not differ with respect to variability of frequency, suggesting that asymmetries in multifrequency coordination were better reflected between the collective behaviour of the bimanual preparations, rather than within differences attributable to the individual components. The intrinsic dynamics commonly observed in preparations of 1:1 coordination were maintained in multifrequency coordination, although quantitative differences were observed between multifrequency assignments. Performance asymmetries observed herein are examined within the framework of the phase-attractive circle map as proposed by DeGuzman and Kelso (1991).