Information-Theoretic Analysis of the Speed-Accuracy Tradeoff with Feedback

Human movements are inherently variable and involve some feedback mechanism. A study of the positional variance in a tapping task reveals that the variance profiles are unimodal in time. In the variance-decreasing phase, the aiming task can be modeled by a Shannon-like communication scheme where information is transmitted from a "source" - determined by the distance to the target at maximum variance - to a "destination" - the movement endpoint - over a "channel" with feedback perturbed by Gaussian noise. Thanks to the feedback link, we show that the variance decreases exponentially at a rate given by the channel capacity. This is confirmed on real data. The proposed information-theoretic model has promise to improve our understanding of human aimed movements.