注意力焦點外的顯著刺激能否攫取注意力：兩種實驗派典的比較

Involuntary Orienting Caused by Salient Stimuli Outside Focal Attention: Comparison of Two Paradigms

過去研究顯示在快速序列視覺呈現（rapid serial visual presentation, RSVP）派典中，若令觀察者在視野中央尋找一個紅色目標物予以辨識，則出現在周邊的紅色干擾物仍能攫取注意力（Folk, Leber, & Egeth, 2002）。然而，另有研究採用線索提示（spatial cueing）派典，發現當注意力事先被中央線索指引至確定的周邊位置時，突現干擾物卻無法攫取注意力（Theeuwes, 1991; Yantis & Jonides, 1990）。上述兩群研究使用的實驗派典不同，可能因此影響注意力的分布，而造成不同的結果。本研究沿用前項派典的紅色目標物，比較兩種實驗派典下的紅色干擾物（與定義目標的特徵相關）或突現干擾物（與定義目標的特徵無關）能否攫取注意力。結果發現，在兩種不同的實驗派典下都是紅色干擾物可以攫取注意力，但突現干擾物不行，顯示先前研究結果的不同並非源自實驗派典的差異，而由綜合兩種實驗派典所得的結果可推論：在注意力焦點範圍之外，與目標定義特徵相符的顯著刺激有最大的可能性得以攫取注意力。

A peripheral red distractor hampers central target identification when the target is defined by red (Folk, Leber, & Egeth, 2002). On the other hand, a peripheral onset distractor fails to affect task performance when the target location is pre-cued by a 100%-valid central cue (Theeuwes, 1991; Yantis & Jonides, 1990). Different paradigms were used in these two sets of studies (RSVP in the former and spatial cueing in the later studies) and this may affect the deployment of attention and the results differently. We asked the participants to search for a red target as in Folk et al. (2002) and compared attentional capture by red distractor (i.e., contingent on the target-defining feature) and onset distractor (i.e., not contingent on the target-defining feature), using the RSVP paradigm (Experiment 1) and the spatial cueing paradigm (Experiment 2 and 3). Results showed that, regardless of which paradigm is used, attentional capture occurs only by the red distractor but not by the onset distractor, suggesting that the different results obtained in previous studies were not caused by different paradigms used. Outside focal attention a salient stimulus that is contingent on the target-defining feature has the highest possibility to capture attention.