Dynamic Coordination Phase and Joint Profiles: Cluster and Fixed-point Shift Techniques

This study aims to represent a more preferential bilateral movement template by introducing empirical measures of cluster (Experiment 1) and fixed-point shift (Experiment 2) during the bimanual coordination. We showed how the phase dynamics can be calculated using the cluster method (analysis 1). Relatively stable patterns defined by the cluster process were employed for the fixed-point shift calculation to compare three joint oscillations (wrist, elbow, and shoulder; Analysis 2). The analysis revealed that (i) anti-phase coordination was less stable underlying the cluster phase and amplitude analysis; a significance that was mainly driven by higher radial variability. (ii) The three joint couplings and noise oscillations showed that they were wider for the distal (wrist) than the proximal (shoulder) areas. (iii) Repetition with one joint (i.e., wrist) may be significantly associated with trial effects; thus, using data of pick only one joint (wrist) but collecting data from different (three) joints seems more reliable to be a typical dependent variable for the trial effect. Observations and suggestions derived from this aspect represent how the bilateral movement calculation methods can be applied to measure the type of coordination stability eliminating of the learning effect stemming from numerous trials.