Visual Influences on Center of Pressure Dynamics in Upright Posture

Abstract

In 2 experiments, participants stood upright with their eyes open or closed and facing forward or to the side; the 2nd experiment also included a manipulation of optical structure. At issue were the effects of different conditions of visual exproprioperception on motions of the body's center of pressure. Also at issue was the utility of 2 characterizations of postural control under the vision manipulation: the fractional Brownian motion (over 2 time scales) and the continuous Ornstein-Uhlenbeck process models. We present a demonstration that the former is perhaps more appropriate, followed by results that suggest that visual exproprioperception reduces effective stochastic activity in the short term and decreases negatively correlated activity in the long term. Results also suggest that this visual effect may be rather general and somewhat independent of the specifics of optical structure, although 1 effect of differential optical structure was observed. We discuss the idea that the 2 times scales could reflect processes of obtaining and using information about stability.