Learning to Reach Via Corrective Movements

Andrew H. Fagg, Andrew G. Barto, James C. Houk

When infants begin to perform goal-directed reaching between approximately 4 and 5 months-of-age, the kinematics of their reaches show multiple accelerations and decelerations of the hand, which appear to reflect a correcting series of submovements. Although each submovement is an inaccurate correction, the sequence of submovements is often successful in reaching the target. By what process does the infant's reach controller come to eventually produce adult-like reaching behavior, characterized by bell-shaped velocity profiles and only occasional corrections? We suggest that motor command parameters are tuned in a supervised learning fashion using training information derived from proprioceptive feedback received during corrective movements. Although this is not high-quality training information, it is sufficient to tune motor command parameters in order to bring a dynamic arm quickly and accurately to the target, as we show in a series of simulations. We also suggest that additional parameters can be tuned to satisfy constraints other than end-point constraints through a reinforcement learning process.

Full Reference:

Fagg, A. H., Barto, A. G., Houk, J. C. (1998) Learning to Reach Via Corrective Movements, Proceedings of the Tenth Yale Workshop on Adaptive and Learning Systems, New Haven, CT, June 10-12, pp. 179-185


Last modified: Tue Apr 27 16:19:07 1999