單側忽略症者之眼球運動與視覺注意力參考架構

Eye Movements and Visual Attentional Frames of Reference in Unilateral Neglect

蔡佩倫(Pei-Luen Tsai) ； 襲充文(Gary C.-W. Shyi)

《職能治療學會雜誌》 26卷1期 (2008/11) Pp. 19-36

https://doi.org/10.6594/JTOTA.2008.26(1).02

摘要

眼球運動和視覺注意力存在密切的關係。本研究旨在探討忽略症的視覺注意力之參考架構－以空間為基或以物體為基，並以眼球運動的分析方法，提供視覺注意力在空間與時間向度上分佈情形的指標。本研究包含四組參與者：忽略症病患組、無忽略症病患組、正常老年組和年輕成人組。視覺搜尋作業的刺激為立體呈現的杯子，主要要求參與者判斷螢幕上出現之杯子的把手位置是否相同，並同時以眼動儀記錄其眼球運動資料。實驗操弄的因子為目標杯子的空間位置和把手的形式（即左側把手或右側把手）。本研究主要假設若病患的表現會受到目標杯子出現之空間位置的影響，其注意力缺失是以空間為基礎；但若病患表現會受目標杯子之把手形式的影響，則其注意力缺失是以物體為基礎。實驗結果發現，除跳躍眼動的平均長度外，忽略症病患的各項表現皆顯著較差：他們均容易忽略患側空間的目標物；即使可以偵測到，其反應時間和跳躍眼動的數目皆顯著增加，主要從近端的兩個區域開始掃描，且無法採取較一致且有效的策略來偵測目標物。雖然忽略症病患在健側空間的表現有顯著的改善，但仍較其他參與者為差，顯示其視覺注意力在健側空間也有缺失。此外，忽略症病患的各項表現只受到目標物呈現位置的影響，而與目標物的形式無關；但在檢視其個別的正答率後發現，多數病患的表現同時呈現以空間為基和以物體為基的忽略效果。文中除討論本研究結果在忽略症之臨床評估的啓示外，也對眼動儀的臨床應用提出建議。

關鍵字

忽略症 ； 視覺注意力 ； 參考架構 ； 眼球運動

並列摘要

There is a close link between eye movements and visual attention. The purpose of this study was to investigate the frames of reference (space-based or object-based) of visual attentional deployment in neglect patients during visual search. In particular, we analyzed eye movements of the participants to provide an indication of the spatial and temporal attentional allocation in the search. Four groups of participants were examined: stroke patients with neglect, stroke patients without neglect, elderly controls, and young controls. Participants performed a visual search task to decide whether or not all the displayed 3-D cups were identical to one another, while their eye movements were recorded. Two variables were manipulated: one was the location in which the target was presented on the display, and the other was the type of cup handle (left-handle or right-handle). We hypothesized that the performances of patients with spacebased neglect would be modulated by target location, and those of patients with object-based neglect would be influenced by target type. The results showed that compared to participants of other three groups, neglect patients produced significantly more errors, longer reaction time, and greater number of saccades. They started their search to the left or right of the middle and employed inefficient search strategies. In particular, neglect patients performed worst when the target appeared on the far-left visual field. Their performances on the right-visual-field target also were significantly worse than those of normal participants, indicating attentional deficits on the ipisilesional side. Moreover, only the location factor had a significant effect on the outcome measures in neglect patients. However, analysis of the accuracy data of individual patients revealed that neglect of most patients was both space-based and object-based. These results demonstrate that the neglect syndromes of these patients indeed reflect visual attention deficits that were both space-based and object-based. Implications for clinical evaluation for neglect syndrome and application of the eye tracking system were discussed.

並列關鍵字

neglect ； visual attention ； frames of reference ； eye movement