Experimental Brain Research

, Volume 161, Issue 1, pp 91–103 | Cite as

Testing hypotheses and the advancement of science: recent attempts to falsify the equilibrium point hypothesis

  • Anatol G. Feldman
  • Mark L. Latash
Research Article


Criticisms of the equilibrium point (EP) hypothesis have recently appeared that are based on misunderstandings of some of its central notions. Starting from such interpretations of the hypothesis, incorrect predictions are made and tested. When the incorrect predictions prove false, the hypothesis is claimed to be falsified. In particular, the hypothesis has been rejected based on the wrong assumptions that it conflicts with empirically defined joint stiffness values or that it is incompatible with violations of equifinality under certain velocity-dependent perturbations. Typically, such attempts use notions describing the control of movements of artificial systems in place of physiologically relevant ones. While appreciating constructive criticisms of the EP hypothesis, we feel that incorrect interpretations have to be clarified by reiterating what the EP hypothesis does and does not predict. We conclude that the recent claims of falsifying the EP hypothesis and the calls for its replacement by EMG-force control hypothesis are unsubstantiated. The EP hypothesis goes far beyond the EMG-force control view. In particular, the former offers a resolution for the famous posture-movement paradox while the latter fails to resolve it.


Motor control theories Threshold control Posture-movement problem Equifinality Stiffness 



AGF was supported by CIHR (Canada), NSERC (Canada), NOTEQ (Quebec), and MLL benefited from NIH grants AG-018751 and NS-35032.


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Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  1. 1.Neurological Science Research Center, Department of PhysiologyUniversity of Montreal and Rehabilitation Institute of MontrealMontrealCanada
  2. 2.Department of KinesiologyThe Pennsylvania State UniversityUSA

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