






How do biological systems stabilize inherently unstable situations,
as in learning to ride a bicycle, maintaining posture, or avoiding falls in
the elderly? In recent investigations, we have utilized the model task of pole
balancing to study the perceptual information used by participants to accurately
time their actions to successfully stabilize an inverted pendulum on a cycle-by-cycle
basis. One such information, the instantaneous time-to-balance, is visually
available in the relative rate of constriction of the pole angle with respect
to the vertical and can be used to modulate the oscillation frequency of the
pole directly. We also examined how two persons or two independent hands collaborate
together before producing the successful coordination between actor(s) and the
pendulum. Here, haptic information about each actor's action, more than the
pole behavior itself, determines the success or failure of the task. This suggests
that a collaboration between the actors must first be established before they
can balance the pole. Ongoing efforts include the investigation of the dynamics
of informational coupling during social coordination, expert performance, and
extensions to the model to encompass these effects.





