Exploring Contextual Interference in Implicit and Explicit Motor Learning

The classic advice given to anyone learning a new skill is \"practice makes perfect.\" While this provides a good general rule to follow, it lacks any detail on what form of practice will efficiently maximize learning. So when faced with the task of acquiring multiple skills, what is the optimal way to learn? Would it be more beneficial to master each skill separately or learn them all at once in an interleaved fashion? A concept known as contextual interference suggests that using a random practice schedule leads to better retention than a blocked one. There are some motor learning studies that are consistent with this hypothesis and some that are not. In order to explore these conflicting results, we applied contextual interference to a simple reaching task that could allow us to observe its effects to various components of motor learning. We had participants learn three different visuomotor rotations and manipulated interference by placing them in groups characterized by how training targets are ordered (blocked vs. random). Using reaction time and hand angle as our measures of performance, we found that participants who experienced a random practice schedule had significant improvements in their ability to retain information, which was manifest as higher levels of implicit adaptation and faster reaction times. However, this did not necessarily mean the information was executed accurately since hand angles did not differ between groups. These findings suggest contextual interference will be most advantageous in situations that require fast explicit recall of a motor plan to use rather than those that emphasize accuracy.