Influence of a visuo-spatial, verbal and central executive working memory task on postural control

In this study, participants were required to perform different working memo ry (WM) tasks (a verbal task, a visuo-spatial task with two levels of diffi culty and a central executive task) under different challenges to postural control (sitting, shoulder width stance and tandem stance). When a WM task was added, changes in postural sway were characterized by an increase in fr equency and decrease in amplitude of sway indicating a tighter control. We found no changes in postural control between the different types of WM task s. which mi ht support a general capacity limitation hypothesis, However, n o changes were found in performance of the WM when postural stance was modi fied and no changes were found in postural sway, when the difficulty level of the visuo-spatial task was modified. Consequently, the results seem to i ndicate that the addition of a WM task, regardless of task type or task dif ficulty, forces the central nervous system to choose a tighter control stra tegy. (C) 2001 Elsevier Science B.V. All rights reserved.