Abstract
Although it is clear that our expectations about the future are critical in determining our behavior, the degree to which they can exert influence over the allocation of attention is in dispute. This debate has been especially intense with regard to the issue of whether expectation about upcoming target features can influence attentional allocation to salient singletons. Recently, Theeuwes & Van der Burg (in press) used the irrelevant singleton paradigm and trial-by-trial cueing to examine the effectiveness of attentional set on the filtering of distractors. They found reaction time benefits to verbal cues that indicated the upcoming target feature (e.g., a diamond or circle), but only when there was an irrelevant distractor present. Our previous work (Leonard & Egeth, in press) has found that there can be benefits of attentional guidance in singleton search displays that lack salient distractors. In this series of studies, we sought to resolve these discrepant findings and also better understand what conditions result in the use of top-down guidance. We used stimuli typical of the irrelevant-singleton paradigm, such that the target was a unique shape in a field of homogenous items, and on some trials a distractor was presented that differed in color from the other items. On each trial, participants received either an informative verbal cue (“diamond” or “circle”) that indicated the shape of the upcoming singleton target or a non-informative verbal cue (“either”). Benefits of informative cues were found overall and, more importantly, this was true in the no-distractor condition, replicating our earlier finding. Several additional experiments explicitly ruled out differences between our study and that of Theeuwes & Van der Burg, such as blocking of distractor presence and absence, as possible accounts for the discrepancy in results. We find that under appropriate conditions, top-down guidance speeds performance, with or without a salient distractor.