Abstract
Can salient stimuli capture spatial attention against our will? To answer this question, many researchers have used the spatial cuing paradigm, in which a salient stimulus (the pcue) is presented shortly before a search display. Degree of capture by the cue is indexed by the cue validity effect: capture should speed up responses when the cue and target are in the same location, but slow responses when they are in different locations. Gaspelin, Ruthruff, and Lien (in press), however, recently questioned this logic. They reported that the same abrupt onset cue can produce either small or large cue validity effects, depending on search difficulty. Cue validity effects, it seems, depend not only on the probability of capture, but also the cost of capture incurred during search (attentional dwelling). The present experiments extended this approach to the study of color singletons. Participants searched for a perfect circle among either heterogeneous ovals (requiring feature search) or homogeneous ovals (enabling singleton search). Feature search yielded little or no cue validity effect, even from highly salient color singletons. Singleton search, however, yielded cue validity effects that increased linearly with search difficulty, ranging from nearly 0 ms with easy search to roughly 100 ms with difficult search. Importantly, difficulty conditions were randomly intermixed, so participants could not adjust their attentional set in anticipation of difficulty level. We conclude that whereas onsets can capture attention based purely on salience, color singletons capture attention only when partially task relevant. Furthermore, we confirmed that search difficulty is a critical determinant of cue validity effects. To ensure sensitivity to attention capture, spatial cuing experiments should employ a difficult search.
Meeting abstract presented at VSS 2017