Selection of experimental frequencies guided by the HKB collective variable dynamics.

Abstract

<p>Humans have shown remarkably consistent coordinative (relative phase) behavior in a wide variety of coordination tasks with rhythmic stimuli, a fact captured by the elementary HKB dynamics <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0005749#pone.0005749-Haken1" target="_blank">[11]</a> illustrated here. When asked to synchronize at the same frequency with the stimulus, stable phase patterns are invariably present at (or close to) anti-phase and in-phase for low movement frequencies (typically <2 Hz). This is indicated by the solid lines of fixed points () when and for <i>f</i> below a critical frequency <i>f*</i>. For frequencies <i>f</i>><i>f*</i>, only the fixed point at is stable. In the VPI experiment, a separate scaling trial in which the frequency is systematically increased is used to determine <i>f*</i>. The value of <i>f*</i> is then used as an upper bound for the choice of frequency parameter, ensuring that pattern instability is not only due to the effect of high frequency in the subject but also comes from conflicting tasks.</p