Anecdotal and scientific evidence suggest humans tend to undershoot targets in rapid movements. We investigated whether this undershoot bias derives from energy minimization mechanisms. Participants performed 200 trials of two tasks: (1) a simple slider push to a target, and (2) a modified version of (1), designed so overshooting was less energy consuming than undershooting. Results support that the undershoot bias found in (1), as well as the overshoot bias found in (2), results from an energy minimization mechanism. Energy minimization might be inherent to biological systems. Movement biases were undesirable for maximal performance. Nonetheless, participants presented biases despite financial incentives to perform maximally. Participants did, however, appear sensitive to systematic errors produced by the attraction to less energy costly responses. We suggest that the motor system is constrained such that maximal performance trades off with energetic optimality although humans are able to learn and compensate for the energy minimization biases.
Oliveira and Goodman are with the School of Kinesiology, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada. Elliott is with the Dept of Kinesiology, McMaster University, Hamilton, ON, L8S 4K1, Canada.