Control becomes habitual early on when learning a novel motor skill.

When people perform the same task repeatedly, their behavior becomes habitual, or inflexible to changes in the goals or structure of a task. Although habits have been hypothesized to be a key aspect of motor skill acquisition, there has been little empirical work investigating the relationship between skills and habits. To better understand this relationship, we examined whether and when people's behavior would become habitual as they learned a challenging new motor skill: maneuvering an on-screen cursor with a nonintuitive bimanual mapping from hand to cursor position. After participants practiced using this mapping for up to 10 days, we altered the mapping between the hands and the cursor to assess whether participants could flexibly adjust their behavior or would habitually persist in performing the task the way they had originally learned. We found that participants' behavior became habitual within 2 days of practice, at which point they were still relatively unskilled. Further practice led to improved skill but did not alter the strength of habitual behavior. These data demonstrate that motor skills become habitual after relatively little training but can nevertheless further improve with practice. We suggest that building habits early in learning may be a crucial step in acquiring new motor skills. Habits and motor skills have often been thought to be deeply related, but very few studies have empirically examined the relationship between the two. We present evidence that habits emerge early in learning, long before a motor skill has been fully learned. Our results suggest that habits may play an integral role in the learning and performance of motor skills from even the early stages of acquiring a new skill.