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The case for an internal dynamics model versus equilibrium point control in human movement


Hinder, MR and Milner, TE, The case for an internal dynamics model versus equilibrium point control in human movement, Journal of Physiology, 549, (3) pp. 953-963. ISSN 0022-3751 (2003) [Refereed Article]

Copyright Statement

Copyright 2003 The Physiological Society

DOI: doi:10.1113/jphysiol.2002.033845


The equilibrium point hypothesis (EPH) was conceived as a means whereby the central nervous system could control limb movements by a relatively simple shift in equilibrium position without the need to explicitly compensate for task dynamics. Many recent studies have questioned this view with results that suggest the formation of an internal dynamics model of the specific task. However, supporters of the EPH have argued that these results are not incompatible with the EPH and that there is no reason to abandon it. In this study, we have tested one of the fundamental predictions of the EPH, namely, equifinality. Subjects learned to perform goal-directed wrist flexion movements while a motor provided assistance in proportion to the instantaneous velocity. It was found that the subjects stopped short of the target on the trials where the magnitude of the assistance was randomly decreased, compared to the preceding control trials (P = 0.003), i.e. equifinality was not achieved. This is contrary to the EPH, which predicts that final position should not be affected by external loads that depend purely on velocity. However, such effects are entirely consistent with predictions based on the formation of an internal dynamics model.

Item Details

Item Type:Refereed Article
Keywords:movement control
Research Division:Health Sciences
Research Group:Sports science and exercise
Research Field:Motor control
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the health sciences
UTAS Author:Hinder, MR (Associate Professor Mark Hinder)
ID Code:130072
Year Published:2003
Web of Science® Times Cited:68
Deposited By:Psychology
Deposited On:2019-01-09
Last Modified:2019-04-26

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