The influence of asymmetric force requirements on a multi-frequency bimanual coordination task

Abstract

An experiment was designed to determine the impact of the force requirements on the pro-duction of bimanual 1:2 coordination patterns requiring the same (symmetric) or different(asymmetric) forces when Lissajous displays and goal templates are provided. TheLissajous displays have been shown to minimize the influence of attentional and percep-tual constraints allowing constraints related to neural crosstalk to be more clearlyobserved. Participants (N = 20) were randomly assigned to a force condition in which theleft or right limb was required to produce more force than the contralateral limb. In eachcondition participants were required to rhythmically coordinate the pattern of isometricforces in a 1:2 coordination pattern. Participant performed 13 practice trials and 1 test trialper force level. The results indicated that participants were able to effectively coordinatethe 1:2 multi-frequency goal patterns under both symmetric and asymmetric forcerequirements. However, consistent distortions in the force and force velocity time serieswere observed for one limb that appeared to be associated with the production of forcein the contralateral limb. Distortions in the force produced by the left limb occurredregardless of the force requirements of the task (symmetric, asymmetric) or whether theleft or right limb had to produce more force than the contralateral limb. However, distinctdistortions in the right limb occurred only when the left limb was required to produce 5times more force than the right limb. These results are consistent with the notion that neu-ral crosstalk can influence both limbs, but may manifest differently for each limb depend-ing on the force requirements of the task.