Rejecting an irrelevant singleton in the absence of a competing target.

Theories of visual distraction handling commonly propose that mechanisms of distractor rejection are engaged because irrelevant, salient objects tend to dominate the attentional competition with the target. Consequently, the resulting misallocation of attention is thought to trigger distractor suppression, ultimately reducing unwanted attentional capture. Using a modified version of the classic additional-singleton paradigm based on four consecutive displays in each trial, where the target and the distractor competed for attention only in the last one, we demonstrated that the attentional capture elicited by a color singleton was strongly attenuated when the singleton repeatedly appeared within the same trial, even in the absence of a competing target. Importantly, this capture attenuation was not associated with target impairment when the target appeared at the singleton location, suggesting that the within-trial rejection was likely controlled by an expectation-based mechanism rather than a suppressive one. Our findings point to the existence of distinct within-trial and across-trials rejection mechanisms, potentially operating on different timescales and involving suppressive and nonsuppressive processes.