Motivating Instructions Provoke Large Increases In Volitional Postural Sway

Abstract

Postural sway generally is assessed using static balance tasks. Dynamic “limits of stability” (LoS) tasks have been used, though these typically provide a visual target to inform the direction and amplitude of sway for the participant. Recently, a new version of this task has been developed to better assess volitional sway control. It is unclear what external motivation may do to affect performance on this task. PURPOSE: To explore the effects of verbal encouragement on volitional sway during the LoS protocol on a Balance Tracking System (BTrackS) Balance Plate. METHODS: Forty healthy college students (age 20.1 ± .9 y) performed three trials of LoS, each lasting one minute in duration with five minutes between each trial. Prior to trials 1 and 2, a researcher stated the following instructions: “During this task, I want you to lean in all directions and make the largest blue box possible on the computer screen. The further you lean, the larger the box will get. During this test, please keep your feet completely flat on the board.” Participants were allowed to look at their performance (i.e., total area covered) but were not given any verbal feedback from the researcher. For the 3rd trial, similar instructions were given to each participant except with more emphasis on overall performance: “For this final trial, I want you to lean in all directions as far as you absolutely can. The goal for this trial is to beat your first two attempts. The further you lean, the larger the box will get. Please remember to keep your feet completely flat.” Values for total area covered during each trial were provided by the software and recorded for analysis. RESULTS: Image Here CONCLUSION: Our data show a significant and large increase in volitional sway area after verbal encouragement. This highlights the importance of following the verbal prompt provided by the LoS protocol. Further, it supports the emerging value of volitional sway tasks to fully understand the underlying mechanisms of dynamic postural control.