title: Motor hysteresis in a sequential grasping and pointing task is absent in task-critical joints.
abstract: In a prior study (Schütz et al. in Exp Brain Res 2016. doi: 10.1007/s00221-016-4608-6 ), we demonstrated that the cognitive cost of motor planning did not differ in a vertical pointing and grasping task. It was unclear whether the similar cost implied that both tasks required the same number of independent degrees of freedom (IDOFs) or that the number of IDOFs did not affect motor planning. To differentiate between both cases, a reanalysis of the prior data was conducted. The number of IDOFs in the pointing and grasping tasks was computed by factor analysis. In both tasks, two IDOFs were used, which was the minimum number required for position control. This indicates that hand alignment in the grasping task did not require an additional IDOF. No conclusions regarding the link between the cognitive cost of motor planning and the number of IDOFs could be drawn. A subset of task-critical joint angles was not affected by motor hysteresis. This indicates that a joint's susceptibility to motor hysteresis depends on its relevance to the task goal. In task-critical joints, planning cost minimization by motor plan reuse is suppressed in favor of the task goal.
authors.affiliation: Faculty of Psychology and Sports Science, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany. christoph.schuetz@uni-bielefeld.de.
authors.forename: Christoph
authors.identifier: 0000-0002-3339-9690
authors.initials: C
authors.lastname: Schütz
authors.affiliation: Department of Sports and Health, University of Paderborn, Paderborn, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Weigelt
authors.affiliation: Faculty of Psychology and Sports Science, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany.|Cognitive Interaction Technology, Center of Excellence, Bielefeld University, Bielefeld, Germany.|CoR-Lab, Research Institute for Cognition and Robotics, Bielefeld University, Bielefeld, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schack
mesh_terms: D000465:Algorithms; D001696:Biomechanical Phenomena; D005260:Female; D006225:Hand / Q000502:physiology*; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D007596:Joints / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D025341:Principal Component Analysis; D011597:Psychomotor Performance / Q000502:physiology*; D012399:Rotation
keywords: Factor analysis; Grasping; Motor hysteresis; Motor planning; Pointing