SYNERGIES IN WITHIN- AND BETWEEN-PERSON INTERLIMB RHYTHMIC COORDINATION: EFFECTS OF COORDINATION STABILITY AND ENVIRONMENTAL ANCHORING

 
 
 
 

SYNERGIES IN WITHIN- AND BETWEEN-PERSON INTERLIMB RHYTHMIC COORDINATION: EFFECTS OF COORDINATION STABILITY AND ENVIRONMENTAL ANCHORING

Show full item record


Title: SYNERGIES IN WITHIN- AND BETWEEN-PERSON INTERLIMB RHYTHMIC COORDINATION: EFFECTS OF COORDINATION STABILITY AND ENVIRONMENTAL ANCHORING
Author: BLACK, DAVID PAUL
Description: Synergies have been widely recognized as a way the CNS functionally deals with the degrees of freedom problem (Bernstein, 1967). Results of previous research have suggested the CNS organizes groups of motor elements for context-specific tasks. Recently, the uncontrolled manifold (UCM) hypothesis has been developed to quantitatively detect the existence of synergies and asses the strength of synergies (Scholz & Schöner, 1999). According to this hypothesis a synergy exists when a desired value of a performance variable is preserved by structuring variability within a subspace (the UCM) of the multidimensional space composed of the motor elements (Varcomp) and minimizing variability in the subspace orthogonal to the UCM (Varuncomp). The UCM approach was applied to interlimb rhythmic coordination to determine if relative phase is stabilized as a control variable in both intrapersonal and interpersonal tasks and if the ratio of Varcomp to Varuncomp is affected by parameters associated with reduced coordination stability. Participants oscillated detuned or non-detuned pendulum pairs in either inphase or antiphase coordination modes at or above the coupled wrist-pendulum system’s eigenfrequency. Experiment 1 employed an intrapersonal coordination task while Experiment 2 employed an interpersonal coordination task. Experiment 3 explored the effects of anchoring in within-person coordination. The results of all three experiments were consistent with the HKB model predictions (e.g., greater variability in antiphase, with the detuned pendulums, and when the metronome frequency was greater than the coupled wrist-pendulum system’s eigenfrequency). The UCM analysis quantitatively verified synergies exist during a rhythmic motor task within a single person and between two people. Greater stabilization of relative phase was observed during inphase than antiphase coordination (Varcomp > Varuncomp) and, in Experiments 1 and 2, at the endpoints of the movement cycles. The latter effect was not observed in Experiment 3, when participants attempted to synchronize the endpoints of pendulum oscillations with a metronome. In addition, the interlimb rhythmic coordination synergy was weaker for movement frequencies greater than the coupled wrist-pendulum system’s eigenfrequency. The results of Experiment 2 were consistent with those of Experiment 1 except that interpersonal synergies were weaker than the intrapersonal synergies in Experiment 1. Detuning did not weaken the strength of the interlimb rhythmic coordination synergy. In Experiment 3, the anchoring effect was not observed. Implications of the results for understanding coupling strength and the nature of movement variability were discussed.
Permanent Link: http://rave.ohiolink.edu/etdc/view?acc_num=ucin1129553094
http://hdl.handle.net/2374.OX/11208
Date: 2005

Files in this item

Files Size Format View

There are no files associated with this item.

This item appears in the following Collection(s)

Show full item record