Contextual uncertainty determines early attentional orienting in visual selection

Our attention can be inadvertently captured by irrelevant or distracting stimuli. Past work has shown that knowledge about the search context in which targets and distractors occur, such as where distractors often occur, can greatly reduce attentional capture. In this study, we set out to show that uncertainty about this context (or contextual variability) is another critical determinant of attentional capture by physically salient distractors. Specifically, in three (preregistered) capture-probe experiments (n =288, n = 114, n = 114), we manipulated singleton distractor location and context uncertainty separately from set size. We found that rendering the distractor location less variable did not affect attentional capture. However, when contextual uncertainty was reduced, by keeping parts of the search display fixed across trials or by exposing participants to a restricted set of search configurations, attentional capture disappeared. Our findings support the notion that contextual uncertainty is a critical factor determining whether salient distractors capture attention.