Abstract
This report studies balancing an external visual object, which may share a common process with the clinically important task of maintaining upright bipedal balance. Participants were instructed to keep a virtually simulated unstable object in its upright position by moving a joystick. The unstable object was a circular array of random dots rolling about its center according to the equation of motion of a simple inverted pendulum, with a calibrated pendular rate constant. Information about the object’s angular displacement was eliminated by reducing the ratio of dots moving as a unit relative to jumping randomly per frame (coherence), and information about angular velocity was degraded by reducing the rendering rate (strobing). Eight dependent variables were measured to quantify performance and learning. Experiment 1 (n=32) showed that loss of either position or rate information significantly degrades visual balance ability, with a significantly larger degradation in the absence of rate information. Experiment 2 (n=10) results showed that increasing the strobe rate of image displacement improves performance, with the best performance found at the rate used in Experiment 1. Also, Experiment 2 concluded that a change in random dot kinematogram (RDK) rollover rate impacts performance accuracy more than a change in apparent motion perception.