A test of the beggs’ model for self-paced movements

The model of human motor control developed by Beggs, Howarth and co-workers (eg., Beggs and Howarth 1970, Howarth et al. 1971) shows that in a paced terminal control task the variance of the lateral error distribution, σ₂, is a linear function of the square of the uncontrolled distance, d_v2. This formulation was tested for a self-paced path control task. Six subjects drew along tracks of four widths with the illumination removed at four different distances from the end of the path. Speeds and errors showed close correspondence to previous path control tasks. Lateral error did increase linearly with the square of the uncontrolled distance but at a lower rate for longer dark distances. Poorer control at shorter dark distances was interpreted as the subjects producing sufficient rather than optimal performance.