Effects of force production and trial duration on bimanual performance and attentional demands in a rhythmic...

The current study investigated the influence of resistance to motion and trial duration on the stability of bimanual coordination patterns and attentional demands. Seven participants performed in-phase and antiphase coordination patterns at a frequency of 1.5 Hz for 300 s. Resistance opposed to pronation-supination movements was manipulated. Attentional demands associated with the bimanual coordination patterns performance were measured using a probe reaction-time task. Results showed that variations in the level of resistance to motion, which induced corresponding variations in the amount of muscle activation during both the in-phase and the antiphase pattern, were associated with longer reaction time. Relative phase variability and attentional demands were higher for the antiphase pattern than for the in-phase pattern. Moreover, the attentional demands did not covary with the increase in the antiphase pattern over the trial duration. The inphase pattern remained unaffected by resistance opposed to pronation-supination movement. The present findings and the time effect are discussed according to potential alterations localized in different sites at the cortical level.