Visual effort moderates a self-correcting nonlinear postural control policy

A growing consensus across otherwise disparate perspectives on perception and action is that visually guided postural control emerges from within task constraints. Task constraints generate physiological fluctuations across various parts of the body. These fluctuations foster exploration of the available sensory information. For instance, standard deviation (SD) and temporal correlations of bodily sway can indicate how richly postural control samples available mechanical and visual information. Too much or too little SD entails destabilization of posture. Temporal correlations show a similar relationship, but they have also been shown to support carrying sampled information to other aspects of the postural system. The present study shows that increasing visual constraints on posture reveals an adaptive relationship between SD and temporal correlations of postural fluctuations. In short, changing the viewing distance of a fixation target shows that temporal correlations self-correct themselves across time and diminish SD across time as well. Notably, these relationships were strong for all viewing distances except the most comfortable viewing and reaching distance. This self-correcting relationship allows the visual layout itself to press the postural system into a poise for engaging with objects and events in the surrounding.