The Effect of Optic Flow During Attention Related Tasks and Quiet Stance

Abstract

Vision plays a significant role in balance as it provides visual cues to help maintain balance. Increasing visual information during upright stance leads to tighter regulation of upright stance. Cognitive related tasks and postural control share capacities and compete for cognitive resources which may cause interference on one or both tasks. There is limited work on the impact of visual gain manipulation on dual tasks that include attention tasks that require visual information while maintaining an upright stance. While previous studies have explored how dual tasks and modified visual feedback influence balance separately, there is limited work on the impact of visual feedback during dual tasks that require visual information.

This study explored how visual cues affect balance when combining effects of visual conditions and different cognitive attention tasks. Optic flow was amplified or reduced to 4 gain conditions (0.25x,1x,4x,16x) within virtual reality (VR) relative to the head position while participants stood quietly on a force plate that measure ground reaction forces and completed 12 randomized trials across 3 conditions. Kinematics were collected through 8 markers placed on different parts using motion capture. Muscle activity was also collected by placing EMG on 3 lower leg muscles during the trials. MSRS questionnaire was completed after each trial to assess movement consciousness. Root mean square (RMS), and the mean power frequency (MPF) of Centre of Pressure (COP) and head position (HeadPos) were used to quantify balance. The mean angle RMS of relative angular displacement of the hip, knee and ankle was calculated, and the mean angle RMS of absolute angular displacement of the trunk, thigh, shank, foot was calculated to quantify balance. Developing a greater understanding of complex dynamics of visual feedback on cognitive task that requires vision while quiet standing, may enhance our understanding of how visual information aids postural control during dual tasks.