Does it help to expect distraction? Attentional capture is attenuated by high distractor frequency but not by trial-to-trial predictability

Salient distractors such as color singletons typically capture attention. Recent studies have shown that probabilistic expectations of color singletons' occurrence-even when their location and features are unpredictable-can eliminate attentional capture. Here we ask whether this effect, referred to as "second-order distractor suppression," (a) could be merely a result of repetition priming, and (b) is also observed when distractor occurrences are predictable within a sequence of trials? Experiment 1 introduces a novel approach for manipulating the frequency of distractor occurrence while controlling for intertrial priming by design, by embedding identical trial sequences in the to-be-compared conditions. We observed no elimination but significant attenuation of capture in the condition with a higher distractor frequency. In Experiments 2 and 3 we investigated the effect of the trial-to-trial predictability of distractor presence. Repeating regular distractor absent/present patterns did not result in attenuated capture compared with a random condition, not even when upcoming distractor presence was cued. Taken together, the results demonstrate that second-order distractor suppression is not merely a result of repetition priming. However, it is not a response to any type of expectation; this nonspecific type of suppression is almost instantly elicited by environments characterized by a high likelihood of distractors but not by distractor presence that can be anticipated on a trial-by-trial basis. Public Significance Statement Does it help to expect distracting, task-irrelevant stimuli even if we do not know what a distractor will look like or where it will appear? This study investigated how the frequency of singleton distractors, their occurrence within a predictable sequence, and explicit cues regarding distractor presence in an upcoming display affect attentional capture. It used a novel experimental approach to tightly control intertrial effects. The results suggest that humans are able to very promptly adopt a nonspecific distractor suppression mode (resulting in attenuated attentional capture) upon entering contexts where task-irrelevant distracting stimuli are highly frequent. This same type of suppression is not elicited when the presence of a distractor in an upcoming search display is predictable given the preceding trial sequence, not even with the addition of a cue that explicitly indicated distractor absence or presence. This work highlights the importance of differentiating between different types of statistical regularities (a distribution vs. a trial-to-trial sequence) that could lead to the formation of expectations regarding distraction and modulate attentional capture