根據人口統計相關數據顯示，臺灣從高齡化社會邁向超高齡社會的速度居世界首位，長者的跌倒預防自然是個刻不容緩的問題，其中又以常見的絆倒最值得關注。歷年來已經有許多研究專注探討跌倒的外在因素，提出在地板材質、防護措施等方面的改善對策，而在基於個人特性之內在因素方面，則以高齡者的步態分析為最大宗。然而在步行期間的視覺輔助－亦即腳眼協調之運用-亦有其重要性：例如有研究發現高齡者在進行足部定位時，常因為提早目光轉向導致定位誤差變大、提高跌倒的風險，若能訓練高齡者將視線追隨腳步的移動直至踏上目標為止，將有助於降低定位誤差，避免絆倒。因此，本研究旨在進一步探討此訓練效果的學習性，亦即高齡者能否持續遵守此限制視線的指令，自然地延續至要踩踏的每一個目標，並且針對所觀察到之現象擬定適宜之對策。
本研究招募十位高齡者（55至65歲）及十位年輕人（22到24歲），排除具有慢性疾病與過去一年內曾有跌倒經驗者，在實驗過程中，研究參與者必須配戴眼球軌跡追蹤儀以及電磁感應式動作擷取追蹤器以記錄眼球移動與下肢運動學參數。在指定的路徑上（長4.8公尺、寬1.2公尺）設有兩個踩踏目標，第一個目標的位置固定，第二個目標則隨機出現在第一個目標的後一步、後兩步或後三步。研究參與者以自己習慣的速度向前行走並依序踏上指定的兩個目標，第一階段將限制研究參與者在踩踏第一個目標時必須直視該目標、直至腳跟踩踏到其上為止，第二個目標則沒有限制；第二階段則要求在踩踏兩個目標時皆必須遵守前述的限制，比較兩個階段間在踩踏的定位精準度、完成任務所需時間等數據之差異，即可驗證此限制視線停留位置的策略之學習效果，並分析年齡因素所造成之影響。
然而，在行走的過程中，視線必須同時顧及踩踏目標與周遭環境，否則仍可能與路徑上的物體發生碰撞，因此本研究進一步以前述10位高齡研究參與者探討自視線移入目標至移開的理想時間範圍。在實驗過程中，共有三種策略：第一種限制在前導腳的腳跟著地時將視線移入目標，第二種限制研究參與者在前導腳的腳貼平地面時，視線始移入目標，第三種則是限制跟隨腳的腳尖離地時才將視線移入目標，比較三種視覺策略間在踩踏的定位精準度、完成任務所需時間等數據差異，再評估何種策略較為理想時間範圍。
結果發現高齡者的足部定位誤差明顯大於年輕人，且兩種視覺輔助策略之間存在顯著差異，代表限制視線停留位置之策略無法延續，必須時時提醒才能發揮此腳眼協調策略之效果；進一步探討視線移入目標致移開的理想時間範圍，結果發現前導腳腳貼平地時將視線移入目標為最佳的視覺輔助方式。未來期望能將研究結果提供給專業醫護人員做為臨床訓練之參考，有效提昇高齡者在居家環境中的安全。

Taiwan is changing from an aging society to an aged society very rapidly. The prevention of falls hence becomes one of the most critical issues. There have been many studies focusing on the risk factors of falls, among which the gait patterns of older adults were highlighted. However, the use of foot-eye coordination during walking also plays an important role. As found by previous studies, older adults with high risks of falls often transferred their gaze away from the target earlier, which leads to decreased accuracy of foot positioning. If gaze transfer is not allowed until heel-strike on the target, the more accurate foot positioning may help reduce the risk of falls due to trips or loss of balance.
Ten older adults ranging from 55 to 65 years old and ten young adults ranging from 22 to 24 years old will be recruited in this study. Each participant is required to wear the eye-tracking system and the electromagnetic tracking system, so as to collect the eye movement parameters and gait data. There are two targets placed along the pathway. The first target is placed on a fixed position, while the second one is placed either one-step, two-step, or three-step away from the first one. The participant needs to walk forward while stepping on the first target and then the second target respectively. Under condition 1, the participant is required to keep looking at the first target until heel-strike on it, whereas no instruction is given to the second target. Under condition 2, the participant has to follow the instruction of foot-eye coordination for both targets. By comparing the differences in positioning error and task completion time between the two conditions, it can help determine whether the strategy of visual guidance takes effect over time. However, eye gaze on the target the pathway should be as important as on the environment in order not to make collision with other objects. So the next step is to find out the best timing when visual guidance should be triggered and terminated. The ten elder adults mentioned earlier participated in this experiment again. There are three targets fixed placed the pathway, Under condition 1, the participant is required to look at each target during the heel-strike of leading foot until heel-strike of the trailing foot on it, Under condition 2, the participant is required to look at each target during the foot-flat of leading foot until heel-strike on it. Under condition 3, the participant is required to looking at each target during the toe off of trailing foot until heel-strike on it.
In the first experiment, the results show that foot positioning error is greater both in condition 1 than in condition 2, and in elder than in younger adults. In other words, visual guidance can’t take effect over time. Reminder of this strategy would be hence required during walking. In the second experiment, the results show that the best timing of visual guidance is to be triggered at the foot-flat of leading foot. In the future, the findings may serve as a reference for clinical applications to improve the safety of older adults in the home environment.

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