We explored relations between visual performance and postural control. Variability in postural sway was analyzed in the context of variations in supra-postural visual tasks. We varied target distance (near vs. far) and visual task (inspecting a blank target vs. counting the frequency of letters in a block of text). Variability in postural sway was reduced when participants fixated near targets as opposed to far targets. Also, postural sway during the visual search task was reduced relative to sway during inspection of blank targets. We argue that the search task placed more restrictive constraints on the visual system, and that postural sway was reduced to facilitate visual search. The results support the hypothesis that postural control is not an autonomous system, but is organized as part of an integrated perception-action system. Postural control can be used to improve visual performance.
Bibliographical noteFunding Information:
The study reported in this paper was conducted as part of Randy J. Pagulayan’s Master’s Thesis. Portions of the data were presented at a meeting of the Human Factors and Ergonomics Society, October, 1998. Preparation of this article was supported by the National Science Foundation (SBR-9601351, INT-9603315) and by the Centre National de la Recherche Scientifique (CNRS/NSF-3899), with additional support from the French Ministère de l’Education Nationale, de la Recherche et de la Technologie. We thank Kartika Huston and Jennifer Ernst, who helped with data reduction.