Effect of Dyadic Haptic Collaboration on Ankle Motor Learning and Task Performance

Optimizing skill acquisition during novel motor tasks and (re)learning lost motor functions have been the interest of many researchers over the past few decades. One approach shown to accelerate motor learning is haptically coupling two individuals through robotic interfaces. Studies have shown that an individual’s solo performance of upper-limb tracking tasks may improve after haptically coupled training with a partner. In this study, our goal was to investigate whether these findings can be translated to lower-limb motor tasks, more specifically, during an ankle position tracking task. Using one-degree-of-freedom ankle  movements, pairs of participants (i.e., dyads) tracked target trajectories while intermittently coupled through a virtual spring rendered between two ankle rehabilitation robots. We compared changes in task performance across trials while training with and without haptic coupling. We found that dyadic haptic coupling did not lead to faster individual learning of the tracking task. Dyadic task performance (i.e., tracking performance while haptically coupled) improved during haptic coupling, likely due to averaging of errors of the dyadic pair during tracking. These results suggest that haptic coupling between unimpaired individuals may not be an effective method of training ankle movements during a simple one-degree-of-freedom task.