Dynamical structure of hand trajectories during pole balancing.

We studied the dynamics of fingertip displacement series in human pole balancing using recurrence quantification analysis (RQA). The purpose of this research was to determine how the dynamical structure of fingertip fluctuations evolved with learning. Learning was accompanied by increased stability of movement trajectories in spite of a reduced tendency for movement trajectories to recur. Task manipulations, on the other hand, resulted in more intermittent fingertip dynamics, which suggests that individuals were more tolerant of random fingertip displacements when the task was performed while sitting relative to standing. Such a strategy would minimize the computational burden associated with maintaining pole stability.