Navigating visually complex environments requires focusing on relevant information while filtering out (salient) distractions. The signal suppression hypothesis posits that salient stimuli generate an automatic saliency signal that captures attention unless overridden by learned suppression mechanisms. In support of this, ERP studies have demonstrated that salient stimuli that do not capture attention elicit a distractor positivity (P D ), a putative neural index of suppression. Yet, to date, this hypothesis has been primarily tested with color singletons, leaving it unclear if the P D reflects general suppression or is specific to color singletons. This study compared lateralized ERPs elicited by color singleton and dynamic motion distractors using a variant of the additional singleton paradigm that has been shown to result in proactive suppression of colored distractors. Behavioral results showed a singleton presence benefit for both distractor types, indicating distractor suppression. However, ERP data revealed clear differences in the underlying neural mechanisms: Color singletons elicited a P D component indicative of proactive suppression, whereas motion singletons elicited a later positivity preceded by an N2pc, suggesting reactive suppression. Our findings suggest that motion singletons, unlike color singletons, are suppressed reactively after initial capture. This study highlights the importance of considering distractor feature dimensions in understanding attentional suppression mechanisms and underscores the need for caution in establishing proactive suppression based on a single metric. Further research is needed to clarify the conditions under which the early P D reliably indicates proactive suppression and to explore the neural processes underlying the suppression of various salient distractors.

It is well established that attention can be sharpened through the process of statistical learning (e.g., visual search becomes faster when targets appear at high-relative-to-low probability locations). Although this process of statistically learned attentional enhancement differs behaviorally from the well-studied top–down and bottom–up forms of attention, relatively little work has been done to characterize the electrophysiological correlates of statistically learned attentional enhancement. It thus remains unclear whether statistically learned enhancement recruits any of the same cognitive mechanisms as top–down or bottom–up attention. In the current study, EEG data were collected while participants searched for an ambiguous unique shape in a visual array (the additional singleton task). Unbeknownst to the participants, targets appeared more frequently in one location in space (probability cuing). Encephalographic data were then analyzed in two phases: an anticipatory phase and a reactive phase. In the anticipatory phase preceding search stimuli onset, alpha lateralization as well as the Anterior Directing Attention Negativity and Late Directing Attention Positivity components—signs of preparatory attention known to characterize top–down enhancement—were tested. In the reactive phase, the N2pc component—a well-studied marker of target processing—was examined following stimuli onset. Our results showed that statistically learned attentional enhancement is not characterized by any of the well-known anticipatory markers of top–down attention; yet targets at high probability locations did reliably evoke larger N2pc amplitudes, a finding that is associated with bottom–up attention and saliency. Overall, our findings are consistent with the notion that statistically learned attentional enhancement increases the perceptual salience of items appearing at high-probability locations relative to low-probability locations.

There has been a long-lasting debate about whether salient stimuli, such as uniquely colored objects, have the ability to automatically distract us. To resolve this debate, it has been suggested that salient stimuli do attract attention but that they can be suppressed to prevent distraction. Some research supporting this viewpoint has focused on a newly discovered ERP component called the distractor positivity (P D ), which is thought to measure an inhibitory attentional process. This collaborative review summarizes previous research relying on this component with a specific emphasis on how the P D has been used to understand the ability to ignore distracting stimuli. In particular, we outline how the P D component has been used to gain theoretical insights about how search strategy and learning can influence distraction. We also review alternative accounts of the cognitive processes indexed by the P D component. Ultimately, we conclude that the P D component is a useful tool for understanding inhibitory processes related to distraction and may prove to be useful in other areas of study related to cognitive control.

Although in many cases salient stimuli capture attention involuntarily, it has been proposed recently that under certain conditions, the bottom–up signal generated by such stimuli can be proactively suppressed. In support of this signal suppression hypothesis, ERP studies have demonstrated that salient stimuli that do not capture attention elicit a distractor positivity (P D ), a putative neural index of suppression. At the same time, it is becoming increasingly clear that regularities across preceding search episodes have a large influence on attentional selection. Yet to date, studies in support of the signal suppression hypothesis have largely ignored the role of selection history on the processing of distractors. The current study addressed this issue by examining how electrophysiological markers of attentional selection (N2pc) and suppression (P D ) elicited by targets and distractors, respectively, were modulated when the search target randomly varied instead of being fixed across trials. Results showed that although target selection was unaffected by this manipulation, both in terms of manual response times, as well as in terms of the N2pc component, the P D component was reliably attenuated when the target features varied randomly across trials. This result demonstrates that the distractor P D , which is typically considered the marker of selective distractor processing, cannot unequivocally be attributed to suppression only, as it also, at least in part, reflects the upweighting of target features.

Current theories assume a functional role for covert attention in the maintenance of spatial information in working memory. Consistent with this view, both the locus of attention and positions stored in working memory can be decoded based on the topography of oscillatory alpha-band (8–12 Hz) activity on the scalp. Thus far, however, alpha modulation has been studied in isolation for covert attention and working memory tasks. Here, we applied an inverted spatial encoding model in combination with EEG to study the temporal dynamics of spatially specific alpha activity during a task that required observers to visually select a target location while maintaining another independently varying location in working memory. During the memory delay period, alpha-based spatial tuning functions shifted from the position stored in working memory to the covertly attended position and back again after the attention task was completed. The findings provide further evidence for a common oscillatory mechanism in both the selection and the maintenance of relevant spatial visual information and demonstrate the dynamic trade-off in prioritization between two spatial tasks.