Motor skill learning by increasing the movement planning horizon

TL;DR

This study shows that humans improve motor skills by extending their movement planning horizon, allowing them to anticipate and control longer segments of a path for faster and smoother tracking.

Contribution

It demonstrates that increasing the movement planning horizon is a key mechanism in motor skill learning, supported by experimental evidence using a path tracking task.

Findings

Subjects improved speed and smoothness with practice.

Higher skill correlates with longer future path consideration.

Planning horizon increases as a result of skill acquisition.

Abstract

We investigated motor skill learning using a path tracking task, where human subjects had to track various curved paths as fast as possible, in the absence of any external perturbations. Subjects became better with practice, producing faster and smoother movements even when tracking novel untrained paths. Using a "searchlight" paradigm, where only a short segment of the path ahead of the cursor was shown, we found that subjects with a higher tracking skill took a longer chunk of the future path into account when computing the control policy for the upcoming movement segment. We observed the same effects in a second experiment where tracking speed was fixed and subjects were practicing to increase their accuracy. These findings demonstrate that human subjects increase their planning horizon when acquiring a motor skill.