Practice Boosts Motor Speed and Accuracy, Yet Direction Matters

Researchers had right-handed volunteers steer a stylus-controlled car around a curved track in a two-dimensional racing game. Each participant completed three hundred laps in the first session. They returned later for a second session to test memory and transfer to new tracks. The new tracks were either rotated or required driving in the opposite direction.

Speed rose quickly during training and stayed higher when participants came back, though it did not reach the original peak. The faster performance also appeared on both the rotated and reverse tracks. Accuracy started out high and remained stable across sessions. No extra improvement was seen between sessions, indicating no offline learning. When faced with the unfamiliar tracks, both speed and accuracy dropped briefly.

Path length, a measure of movement efficiency, was kept after training and transferred well to the rotated track. However, reversing the driving direction hurt efficiency, showing a clear direction bias. A follow-up study that flipped the training direction confirmed that counter-clockwise moves stayed slower and less efficient than clockwise moves. Overall, practice created lasting gains, but inherent direction preferences limited how far those gains spread.

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