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Abrupt onsets reflexively shift covert spatial attention. Recent work demonstrated that trial-to-trial information about the probability of a peripheral onset modulated the magnitude of the attentional cueing effect (low probability > high probability). Although onsets were physically identical, pupil responses could have been modulated by information about the probability of the onset's appearance. Specifically, anticipatory constrictions may have preceded high-probability onsets. Here, we tested this hypothesis using centrally presented, luminance-matched onset-probability signals. For half the participants, vertical signaled high probability (0.8) of onset appearance, while horizontal signaled low probability (0.2). Contingencies were reversed for the other half. Participants fixated the onset-probability signal for 2,000 ms before the onset was briefly presented or omitted, in line with the signaled probability. To maintain engagement, participants completed a simple localization task. Preliminary evidence for an anticipatory reduction in the pupil area was obtained in Experiment 1. However, this effect disappeared in Experiment 2 with a larger replication sample. Exploratory analyses uncovered a violation of a fundamental methodological assumption: despite being task-irrelevant and perfectly luminance-matched, vertical onset-probability signals consistently generated smaller pupil areas, relative to horizontal signals in both Experiments 1 and 2. Interestingly, this “orientation effect” was stronger in the second half of the experimental session, and in a third experiment, we significantly reduced its magnitude by changing the locations of the task-relevant stimuli. In short, across three experiments (self-reported gender, 52 females, 26 males, 1 nonbinary), we show that even with perfect luminance matching, unforeseen changes in cognitive state can modulate pupillometric measurements. 

Abstract Visual attention, the selective prioritization of sensory information, is crucial in dynamic, information-rich environments. That both internal goals and external salience modulate the allocation of attention is well established. However, recent empirical work has found instances of experience-driven attention, wherein task-irrelevant, physically non-salient stimuli reflexively capture attention in ways that are contingent on an observer’s unique history. The prototypical example of experience-driven attention relies on a history of reward associations, with evidence attributing the phenomenon to reward-prediction errors. However, a mechanistic account, differing from the reward-prediction error hypothesis, is needed to explain how, in the absence of monetary reward, a history of target-seeking leads to attentional capture. Here we propose that what drives attentional capture in such cases is not target-seeking, but an association with instrumental information. To test this hypothesis, we used pre-cues to render the information provided by a search target either instrumental or redundant. We found that task-irrelevant, physically non-salient distractors associated with instrumental information were more likely to draw eye movements (a sensitive metric of information sampling) than were distractors associated with redundant information. Furthermore, saccading to an instrumental-information-associated distractor led to a greater behavioral cost: response times were slowed more severely. Crucially, the distractors had equivalent histories as sought targets, so any attentional differences between them must be due to different information histories resulting from our experimental manipulation. These findings provide strong evidence for the information history hypothesis and offer a method for exploring the neural signature of information-driven attentional capture.