Modulating postural control to facilitate visual performance

We explored relations between visual performance and postural control. Vari ability 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 b lank targets. We argue that the search task placed more restrictive constra ints 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 percep tion-action system. Postural control can be used to improve visual performa nce. (C) 2000 Elsevier Science B.V. All rights reserved. PsycINFO classific ation. 2323; 2330; 2346; 4010.