不穩定視覺環境的閱讀姿勢控制

姿勢控制與動暈的發生有關，基於姿勢不穩定理論，個體發生動暈前會先呈現姿勢不穩定，其為不適應持續改變環境，進而無法達到姿勢控制的穩定狀態。本研究旨在針對交通器上閱讀容易動暈之議題，探討視覺擾動、姿勢、及閱讀目標呈現方式在閱讀姿勢控制的效應。操弄變項為移動室產生光流、站姿與坐姿、及閱讀目標呈現方式（無閱讀目標、手持、與立地固定），共招募15名參與者於12種實驗情境中閱讀文章，量測參與者之頭部與軀幹移動，用以分析身體擺動、頸部控制、與頭－室配連等依變項。結果顯示：一、站姿比坐姿有較大身體擺動，而目標呈現方式對坐與站姿擺動有不同的效果，站姿閱讀立地固定目標時身體擺動會減少，而坐姿時則是手持閱讀有較大的身體擺動；二、視覺擾動會減低坐姿的頭部與軀幹配連，意指個體在此情況下會有較多頸部調整；三、坐姿和閱讀手持目標有較低的頭－室配連，其中因坐姿較穩定，個體控制姿勢較不依賴視覺；閱讀手持目標時較少擷取周邊視覺訊息，造成身體擺動較大。本研究結論：坐姿頸部控制易受視覺擾動影響；手持閱讀的姿勢穩定性較低，且較少擷取周邊視覺訊息，因此在交通器上閱讀應注意坐姿與手持閱讀情境的姿勢穩定性。

關鍵字

身體擺動；姿勢不穩定；知覺―行動；動暈；移動室

並列摘要

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.