title: Error Correction and the Structure of Inter-Trial Fluctuations in a Redundant Movement Task.
abstract: We study inter-trial movement fluctuations exhibited by human participants during the repeated execution of a virtual shuffleboard task. Focusing on skilled performance, theoretical analysis of a previously-developed general model of inter-trial error correction is used to predict the temporal and geometric structure of variability near a goal equivalent manifold (GEM). The theory also predicts that the goal-level error scales linearly with intrinsic body-level noise via the total body-goal sensitivity, a new derived quantity that illustrates how task performance arises from the interaction of active error correction and passive sensitivity properties along the GEM. Linear models estimated from observed fluctuations, together with a novel application of bootstrapping to the estimation of dynamical and correlation properties of the inter-trial dynamics, are used to experimentally confirm all predictions, thus validating our model. In addition, we show that, unlike "static" variability analyses, our dynamical approach yields results that are independent of the coordinates used to measure task execution and, in so doing, provides a new set of task coordinates that are intrinsic to the error-regulation process itself.
authors.affiliation: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania, United States of America.
authors.forename: Joby
authors.initials: J
authors.lastname: John
authors.affiliation: Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, Texas, United States of America.
authors.forename: Jonathan B
authors.initials: JB
authors.lastname: Dingwell
authors.affiliation: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania, United States of America.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Cusumano
mesh_terms: D000328:Adult; D016000:Cluster Analysis; D019295:Computational Biology / Q000379:methods / Q000592:standards; D006801:Humans; D016014:Linear Models; D008297:Male; D009068:Movement / Q000502:physiology*; D015588:Observer Variation; D011597:Psychomotor Performance / Q000502:physiology*; D013647:Task Performance and Analysis