Effector independence

Although effector independence is predicted in a number of theoretical perspectives, it has received only moderate empirical support. The authors conducted 3 experiments to determine the extent to which simple motor sequences are effector independent. A measurement scheme that partitioned response errors into independent error measures attributable to the relative structure of the response and the force-time scaling of that structure was used in the analysis of the present experiments. The results indicated that the relative structure of the response could be effectively transferred from one limb to the contralateral limb (Experiment 1), to a different muscle group on the same limb (Experiment 2), and from a static to a dynamic version of the task (Experiment 3). The ability to scale force was effector dependent, however, and the force scaling was relatively ineffective when an unpracticed limb was used. Although participants (Ns = 20, 24, and 20, respectively, in Experiments 1, 2, and 3) were effective in transferring the movement structure from a static to a dynamic version of the task, they were not very effective in transferring from a dynamic to a static version of the task. The transfer difference appeared to be related to the information that was available to support performance of the dynamic version of the task, which was not available in producing the static version.