Abstract:
In this study, we aimed to examine features of interlimb generalization or "transfer" of newly acquired motor skills with a broader goal of better understanding the mechanisms mediating skill learning. Right-handed participants (n=36) learned a motor task that required them to make very rapid but accurate reaches to 1 of 8 randomly presented targets, thus bettering the typical speed-accuracy tradeoff. Subjects were divided into an "RL" group that first trained with the right arm and was then tested on the left, and an "LR" group that trained with the left arm and was subsequently tested on the right. We found significant interlimb transfer in both groups. Remarkably, we also observed that participants learned faster with their left arm compared to the right. We hypothesized that this could be due to a previously suggested left arm-right hemisphere advantage for movements under variable task conditions. To corroborate this, we recruited two additional groups of participants (n=22) that practiced the same task under a single target condition. This removal of task level variability eliminated learning rate differences between the arms, yet, interlimb transfer remained robust and symmetric, as in the first experiment. Additionally, the approach adopted to reduce errors during learning, though heterogeneous across subjects particularly in our second experiment, was transferred to the untrained arm. These findings may be best explained as the outcome of the operation of cognitive strategies during the early stages of motor skill learning.