The bilateral transfer of force control in a sequential task is affected by its intensity

Previous research by Yao, W.X., Cordova, A., & Yan, A.F, demonstrated that the learning effect of a sequential task consisting of timing and force controls was significantly transferred to the untrained limb for the timing control alone and not force control. These finding suggests that force control may not be a favorable candidate for a bilateral transfer. However, it is premature for this suggestion because Yao et al.'s (2011) finding could be caused by the high complexity of the task (i.e., consisting of both timing and force controls) and/or the low intensity of the force (i.e., only 10% of the MVC) used in their study. The purpose of the current study, therefore, was to examine these two confounding factors that might have affected Yao et al.'s (2011) results. The current study consisted of two experiments. Each experiment had two groups (i.e., practice and control) and each group had 15 right-handed participants. The first experiment was aimed at examining the effect of the task complexity on the bilateral transfer of force control. The participants of the practice group in the experiment learned a sequential task with their right hand which was similar to the one used by Yao et al. (2011) but consisted of the low force control only (10% of the MVC). The results of the experiment showed that after the practice the practice group improved their force control significantly compared to the pretest and to the control group. However, this learning effect was not transferred to the untrained hand. The second experiment was to determine the effect of force intensity on the bilateral transfer of force control. The participants of the practice group in this experiment learned the same task as the participants in the first experiment but with higher force intensity (i.e., 50% of the MVC). The results showed that the practice group did not only improve the force control with the trained hand and this learning effect was also significantly transferred to the untrained hand. Putting together, the findings of the current study indicate that the force intensity, rather than the task complexity per se, has significant impact on the bilateral transfer of the force control. However, it should be noted that, due to the limitation of the current study, it is unknown if the same transfer effect found in the second experiment would still exist when a learned sequential task consisted of both timing control and high intensity force controls (e.g., .50% of the MVC).