Collective Variables and Task Constraints in Movement Coordination, Control and Skill

Karl M. Newell, Yeou Teh Liu*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

17 Citations (Scopus)


In this paper we review studies that have identified collective variables (order parameters) in movement coordination, control and skill with emphasis on whole-body multiple joint degree of freedom (DF) tasks. Collective variables of a dynamical system have been proposed formally and informally from a diverse set of perceptual-motor tasks, from which we emphasize: bimanual coordination, locomotion (pedalo, walking, running, bicycle riding), roller ball task, static (quiet standing) and dynamic (moving on a ski-simulator) balance, grasping, and juggling. Several types of candidate collective variables have been identified, including: relative phase, frequency ratio, number of hands active in grasping, synchrony, learning rate and relative timing. There is a strong influence of the task goal in determining the collective variable that can be body or environment relative. The emergence of the task relevant collective variable is typically in the early stage of skill learning where subjects through practice adapt movement organization to realize a never previously produced movement coordination pattern. Throughout, the paper elaborates on open theoretical, experimental and analysis issues for collective variables in the context of task constraints and Bernstein’s (1967) view of skill acquisition as learning to master redundant DF.

Original languageEnglish
Pages (from-to)770-796
Number of pages27
JournalJournal of Motor Behavior
Issue number6
Publication statusPublished - 2021


  • Coordination
  • PCA
  • degeneracy
  • degrees of freedom
  • early stage of learning
  • learning
  • motor tasks
  • movement
  • posture
  • whole body actions

ASJC Scopus subject areas

  • Biophysics
  • Orthopedics and Sports Medicine
  • Experimental and Cognitive Psychology
  • Cognitive Neuroscience


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