變焦的注意力：探索顯著共線物體阻撓搜尋的原因

Focus Size of Attention: Exploring the Focus Hypothesis on the Collinear Masking Effect in Visual Search

在搜尋視野內的物體時，通常顯著的或是與正要找的目標特徵吻合的物體會吸引我們的注意力。但是Jingling與Tseng（2013）卻發現一個有趣的現象，即在一個特殊的搜尋畫面中，顯著的目標卻比不顯著的目標還要難找到。此特殊的搜尋畫面是由排列整齊的小線段構成，其中顯著的物體是由多個彼此共線排列的線段形成的，稱為共線干擾物，其干擾目標搜尋的效果稱為共線遮蔽效果。在他們的實驗中此共線干擾物橫跨數個線段長，但目標僅佔一個線段長，因此一個可能的解釋是共線干擾物和目標所張開的注意力範圍彼此衝突所致。本研究的目的即探索注意力聚焦範圍是否可以影響共線遮蔽效果。我們操弄目標大小來調整由上往下的注意力範圍，並操弄干擾物長度來調整由下往上的注意力範圍。結果五個實驗都一致地發現共線遮蔽效果，不受目標大小的影響。故注意力範圍無法解釋共線遮蔽效果。我們認為共線遮蔽效果可能與共線造成的其他知覺特性有關。

In searching for an item in our visual field, a salient or a behaviorally relevant item usually captures our attention. However, Jingling and Tseng (2013) reported an interesting finding that a salient targe t is actually more difficult to identify than a non-salient target. This novel phenomenon was observed in a specific search display, which was filled with regularly aligned small bars. The salient structure was formed by several bars collinear to each other. When the target was on the salient collinear structure, search was more difficult than when the target was in the background, which is called collinear masking effect. Since the target was a small bar while the collinear structure was longer, they may elicit different focus size and disagree to each other. The goal of this study was to test whether the disagreement on focus size can explain the collinear masking effect. We manipulated the size of the target and the size of the collinear structure systematically. Results of five experiments consistently showed the collinear masking effect regardless of the size of the target. These results argue against the focus size hypothesis. We thus conclude that the collinear masking effect might be associated with other perceptual properties rather than the size of the attention focus.