The λ model of the equihbrium-point hypothesis (Feldman & Levin, 1995) is an approach to motor control which, like physics, is based on a logical system coordinating empirical data. The model has gone through an interesting period. On one hand, several nontrivial predictions of the model have been successfully verified in recent studies. In addition, the explanatory and predictive capacity of the model has been enhanced by its extension to multimuscle and multijoint systems. On the other hand, claims have recently appeared suggesting that the model should be abandoned. The present paper focuses on these claims and concludes that they are unfounded. Much of the experimental data that have been used to reject the model are actually consistent with it.
Anatoi G. Feldman, Mindy F. Levin, and Arnold B. Mitnitski are with the Centre de Recherche, Institut de réadaptation, Université de Montréal, Montréal, PQ, Canada H3S 2J4. David J. Ostry and Paul L. Gribble are with McGill University, Department of Psychology, 1205 Dr. Penfield Ave., Montreal, PQ, Canada H3A 1B1.