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 the present 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 capture-probe experiments (n=288, n=114, n=114, respectively; experiments 2 and 3 were preregistered), we manipulated singleton distractor location and context uncertainty separately from set size to determine the effect of uncertainty about distractor location and context on attentional capture. We found that rendering the distractor location less variable did not affect attentional capture, as recall of letters at singleton locations remained higher than at non-singleton distractor control locations. However, when contextual uncertainty was reduced, either 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.