This paper presents the background, premises, and results of a model of movement planning. The model's central claims are fourfold: (a) A task is defined by a set of prioritized requirements, or what we call a constraint hierarchy; (b) movement planning works first by specifying a goal posture and then by specifying a movement to that goal posture; (c) movements have characteristic forms; and (d) movements can be shaped through simultaneous performance of different movements, even by the same effector. We review the model and then speculate on its implications for clinical concerns, especially spasticity.
D.A. Rosenbaum is with the Department of Psychology at Pennsylvania State University. University Park, PA 16802-3408. R.G.J. Meulenbroek is with the Nijmegen Institute for Cognition and Information, P.O. Box 9104, 6500 HE Nijmegen, The Netherlands. J. Vaughan is with the Department of Psychology at Hamilton College, Clinton, NY 13323. The article is based on a talk presented at the International Workshop on Studies and Models of Human Prehension: Contributions to Understanding Grasping Pathology, Werkenrode. Groesbeek, The Neüierlands, January 13, 2000.