The Priority of Color in Working-Memory-Driven Ocular Capture

Abstract

The target template maintaining in working memory can guide attention bias to target-like items in the visual scene facilitating the visual search. In addition to the target template, representations in worming memory that are irrelevant to the search target have also been shown to guide attention in a top-down way. During visual search, the distractor sharing attributes with the online working memory representations capture more attention than other distractors, displaying a robust memory-driven attentional capture effect. However, not all stimulus attributes of the working memory representations are equal effective in capturing attention, previous studies showed that the color attribute of a memory-matched distractor was more effective in capturing the first fixation than the shape attribute. According to the opinion of Wolfe and Horowitz(2004), the color attribute was one of the "undoubted guiding attributes" that had greater efficiency for attention guidance than the shape attribute. So it is unclear yet whether color still has such priority when directly competing against the orientation attribute that is also one of the "undoubted guiding attributes". Three experiments using the classic dual task paradigm were reported here to address this issue. In Experiment 1, participants were asked to search for a specific target accompanied with a distractor which was always located in the opposite visual field of the target. The target and the distractor were respectively embedded in the bar with color and/or orientation attributes same to or different from the objects held in the working memory. The results suggested that the bar would capture more first fixations(i.e. ocular capture effect) only when it shared color attribute with the memory items than when it did not, most importantly, the color-matched bar still captured more first fixations than the orientation-matched bar while they simultaneously appeared and directly competed for attention. In Experiment 2 and 3, participants were required to search either color or orientation of the remembered object. The results showed that in the color search task, ocular capture occurred when the color attributes of the target matched the remembered object regardless of the orientation attribute. However, in the orientation search task, ocular capture still occurred when the distractor was of the same color as the remembered object and slowed down search. These asymmetric results again demonstrated the priority of color attribute in the working memory representation. In conclusion, these results indicate that attentional priority could modulate attentional guidance from working memory, and the color attribute is of greater attentional priority for ocular capture than orientation.