Attentional Guidance by Irrelevant Features Depends on Their Successful Encoding Into Working Memory

Attentional selection is guided by templates of the target in working memory. It has been proposed that attentional templates integrate target features (e.g., purple chair) to guide attention in an object-based fashion. Alternatively, it may be that attentional templates are established for each target feature individually (e.g., purple and chair). To provide support for the latter account, we used a task where participants memorized a target shape while ignoring an irrelevant color. In the combined condition, the shape was shown in the irrelevant color. In the separate condition, the irrelevant color was spatially separate from the shape. After the initial presentation and a blank retention interval, participants were asked to make a saccade to the initially viewed shape, which was shown together with a distractor. Attentional guidance by the irrelevant color was strongly reduced with separate presentation, suggesting that guidance is object-based. However, it may be that irrelevant color was less reliably encoded with separate presentation. Therefore, we asked participants to store the irrelevant color for later recall. With the additional memory task, guidance by irrelevant color occurred regardless of whether it was presented as part of an object or separately. Thus, effects of irrelevant features are easier to observe with combined presentation because all features of an object are automatically encoded into working memory, where they form integrated feature templates. Nonetheless, guidance by separate features is possible, but the poor encoding of irrelevant features with separate presentation makes it more difficult to observe. Public Significance Statement This study shows that any irrelevant feature stored in visual working memory can interfere with attentional selection of the target object. Interference is not limited to situations where the irrelevant feature is part of the target object.