Humans demonstrate a remarkable ability to generate accurate and appro
priate motor behavior under many different and often uncertain environ
mental conditions. In this paper, we propose a modular approach to suc
h motor learning and control. We review the behavioral evidence and be
nefits of modularity, and propose a new architecture based on multiple
pairs of inverse (controller) and forward (predictor) models. Within
each pair, the inverse and forward models are tightly coupled both dur
ing their acquisition, through motor learning, and use, during which t
he forward models determine the contribution of each inverse model's o
utput to the final motor command. This architecture can simultaneously
learn the multiple inverse models necessary for control as well as ho
w to select the inverse models appropriate for a given environment. Fi
nally, we describe specific predictions of the model, which can be tes
ted experimentally. (C) 1998 Elsevier Science Ltd. All rights reserved
.