Postural Control during Reading in Unstable Visual Environment
黃嘉君(Chia-Chun Huang)；楊梓楣(Chih-Mei Yang)
身體擺動 ； 姿勢不穩定 ； 知覺―行動 ； 動暈 ； 移動室 ； body sway ； postural instability ； perception-action ； motion sickness ； moving room
|Volume or Term/Year and Month of Publication||
14卷2期（2012 / 06 / 01）
161 - 169
Postural control is associated with motion sickness. Based on postural instability theory, motion sickness follows prolonged postural instability, which is due to the mal adaptation to changing environment. The purpose of this study was to focus on the issue of higher occurrence of motion sickness in individual, while reading during transportation. Fifteen participants were recruited and asked to read articles in 12 conditions. The effects of visual perturbation, stance types and presented ways of reading targets on postural control were investigated, while reading. Manipulated variables were optic flow generated by moving room, sitting and standing stance, and presented ways of reading targets (no-target, hand-held and fixed). Participants' head and trunk motions were recorded for the analysis of variables of body sway, neck control (head-trunk coupling) and head-room coupling. The results showed as follows: 1. Body sway was higher in standing than in sitting. There were different effects of target presented ways on body sway in sitting and standing. Body sway reduced while reading a fixed target in standing, but increased while reading the hand-held target in sitting. 2. Increase in neck adjustment indicates reduced head-trunk coupling in sitting conditions with visual perturbation. 3. Head-room coupling was lower in sitting conditions and hand-held target. The control of sitting posture relied less on visual information because of the high stability. Individuals pick up less peripheral visual information when reading a hand-held target, further induced higher postural sway. It is concluded that the neck control of sitting tends to be influence by visual perturbation. There was lower postural stability and less pick up of visual information in hand-held reading. When individual is reading while traveling, the postural stability should be concerned in conditions of sitting and handheld target.