Error amplification improves performance by reducing motor noise

Information about error via visual feedback presents important information to promote motor learning. Amplifying error information has shown to be beneficial but the mechanism(s) behind such benefits have not been elucidated. We used a virtual throwing task and model-based system identification to test the hypothesis that performance improvement could not only be attained by an increase in feedback gain, but also by a decrease in intrinsic motor noise. The experiment manipulated the visual error by amplification at three gain levels. Some groups received error amplification with added noise. The experimental results showed that error amplification improved task performance, consistent with previous studies. The system identification results, based on a previously validated learning model, showed that this improvement was brought about primarily by a reduction in the overall amount of intrinsic motor noise, supporting our hypothesis. However, contrary to our expectations, adding noise to the error amplification did not enhance this effect.