Abstract
It was observed that search-irrelevant features stored in working memory guide attention. That is, stimuli matching the stored feature capture attention in a search task occurring between encoding of the irrelevant feature and memory test. We asked whether attentional capture during search occurred only to a single stimulus or whether it would occur continuously to several stimuli. Participants memorized the shape of a colored object before they searched a rotated T among randomly rotated Ls. The set size of the search display varied between 8, 12, and 18 items. The color of half the stimuli matched the irrelevant color of the memorized shape, whereas it was different for the other half. In one experiment, we observed that RTs increased by 59 ms when the target was among the stimuli in a non-matching color compared to when it was among the stimuli in a matching color. However, the search slopes were the same (16 ms/item). When we changed the target shape to make search more serial, the effect of color match was 141 ms and the search slope was larger when the target was among nonmatching than matching stimuli (48 vs. 60 ms/item). However, the difference in search slopes was limited to the large set sizes (12 and 18 items). Overall, an irrelevant feature in working memory guides attention to matching stimuli, but not continuously. Rather, memory-based capture is mostly one-shot.