Getting rid of visual distractors: the why, when, how, and where

Conflicting Sensory Information Sharpens the Neural Representations of Early Selective Visuospatial Attention

Adaptive behaviors require the ability to resolve conflicting information caused by the processing of incompatible sensory inputs. Prominent theories of attention have posited that early selective attention helps mitigate cognitive interference caused by conflicting sensory information by facilitating the processing of task-relevant sensory inputs and filtering out behaviorally irrelevant information. Surprisingly, many recent studies that investigated the role of early selective attention on conflict mitigation have failed to provide positive evidence. Here, we examined changes in the selectivity of early visuospatial attention in male and female human subjects performing an attention-cueing Eriksen flanker task, where they discriminated the shape of a visual target surrounded by congruent or incongruent distractors. We used the inverted encoding model to reconstruct spatial representations of visual selective attention from the topographical patterns of amplitude modulations in alpha band oscillations in scalp EEG (∼8-12 Hz). We found that the fidelity of the alpha-based spatial reconstruction was significantly higher in the incongruent compared with the congruent condition. Importantly, these conflict-related modulations in the reconstruction fidelity occurred at a much earlier time window than those of the lateralized posterior event-related potentials associated with target selection and distractor suppression processes, as well as conflict-related modulations in the frontocentral negative-going wave and midline-frontal theta oscillations (∼3-7 Hz), thought to track executive control functions. Taken together, our data suggest that conflict resolution is supported by the cascade of neural processes underlying early selective visuospatial attention and frontal executive functions that unfold over time.

The inhibitory effect of a recent distractor: singleton vs. multiple distractors

In the complex interplay between sensory and cognitive processes, the brain must sift through a flood of sensory data to pinpoint relevant signals. This selective mechanism is crucial for the effective control of behaviour, by allowing organisms to focus on important tasks and blocking out distractions. The Inhibition of a Recent Distractor (IRD) Task examines this selection process by exploring how inhibiting distractors influences subsequent eye movements towards an object in the visual environment. In a series of experiments, research by Crawford et al. (2005a) demonstrated a delayed response to a target appearing at the location that was previously occupied by a distractor, demonstrating a legacy inhibition exerted by the distractor on the spatial location of the upcoming target. This study aimed to replicate this effect and to investigate any potential constraints when multiple distractors are presented. Exploring whether the effect is observed in more ecologically relevant scenarios with multiple distractors is crucial for assessing the extent to which it can be applied to a broader range of environments. Experiment 1 successfully replicated the effect, showing a significant IRD effect only with a single distractor. Experiments 2-5 explored a number of possible explanations for this phenomenon.

Semantically congruent bimodal presentation modulates cognitive control over attentional guidance by working memory

Although previous studies have well established that audiovisual enhancement has a promoting effect on working memory and selective attention, there remains an open question about the influence of audiovisual enhancement on attentional guidance by working memory. To address this issue, the present study adopted a dual-task paradigm that combines a working memory task and a visual search task, in which the content of working memory was presented in audiovisual or visual modalities. Given the importance of search speed in memory-driven attentional suppression, we divided participants into two groups based on their reaction time (RT) in neutral trials and examined whether audiovisual enhancement in attentional suppression was modulated by search speed. The results showed that the slow search group exhibited a robust memory-driven attentional suppression effect, and the suppression effect started earlier and its magnitude was greater in the audiovisual condition than in the visual-only condition. However, among the faster search group, the suppression effect only occurred in the trials with longer RTs in the visual-only condition, and its temporal dynamics were selectively improved in the audiovisual condition. Furthermore, audiovisual enhancement of memory-driven attention evolved over time. These findings suggest that semantically congruent bimodal presentation can progressively facilitate the strength and temporal dynamics of memory-driven attentional suppression, and that search speed plays an important role in this process. This may be due to a synergistic effect between multisensory working memory representation and top-down suppression mechanism. The present study demonstrates the flexible role of audiovisual enhancement on cognitive control over memory-driven attention.

Orienting role of the putative human posterior infero-temporal area in visual attention

The dorsal attention network (DAN) is a network of brain regions essential for attentional orienting, which includes the lateral intraparietal area (LIP) and frontal eye field (FEF). Recently, the putative human dorsal posterior infero-temporal area (phPITd) has been identified as a new node of the DAN. However, its functional relationship with other areas of the DAN and its specific role in visual attention remained unclear. In this study, we analyzed a large publicly available neuroimaging dataset to investigate the intrinsic functional connectivities (FCs) of the phPITd with other brain areas. The results showed that the intrinsic FCs of the phPITd with the areas of the visual network and the DAN were significantly stronger than those with the ventral attention network (VAN) areas and areas of other networks. We further conducted individual difference analyses with a sample size of 295 participants and a series of attentional tasks to investigate which attentional components each phPITd-based DAN edge predicts. Our findings revealed that the intrinsic FC of the left phPITd with the LIPv could predict individual ability in attentional orienting, but not in alerting, executive control, and distractor suppression. Our results not only provide direct evidence of the phPITd's functional relationship with the LIPv, but also offer a comprehensive understanding of its specific role in visual attention.

Multifaceted consequences of visual distraction during natural behaviour

Visual distraction is a ubiquitous aspect of everyday life. Studying the consequences of distraction during temporally extended tasks, however, is not tractable with traditional methods. Here we developed a virtual reality approach that segments complex behaviour into cognitive subcomponents, including encoding, visual search, working memory usage, and decision-making. Participants copied a model display by selecting objects from a resource pool and placing them into a workspace. By manipulating the distractibility of objects in the resource pool, we discovered interfering effects of distraction across the different cognitive subcomponents. We successfully traced the consequences of distraction all the way from overall task performance to the decision-making processes that gate memory usage. Distraction slowed down behaviour and increased costly body movements. Critically, distraction increased encoding demands, slowed visual search, and decreased reliance on working memory. Our findings illustrate that the effects of visual distraction during natural behaviour can be rather focal but nevertheless have cascading consequences.

10 Hz rhythmic stimulation modulates electrophysiological, but not behavioral markers of suppression

We investigated the role of alpha in the suppression of attention capture by salient but to-be-suppressed (negative and nonpredictive) color cues, expecting a potential boosting effect of alpha-rhythmic entrainment on feature-specific cue suppression. We did so by presenting a rhythmically flickering visual bar of 10 Hz before the cue - either on the cue's side or opposite the cue -while an arrhythmically flickering visual bar was presented on the respective other side. We hypothesized that rhythmic entrainment at cue location could enhance the suppression of the cue. Testing 27 participants ranging from 18 to 39 years of age, we found both behavioral and electrophysiological evidence of suppression: Search times for a target at a negatively cued location were delayed relative to a target away from the cued location (inverse validity effects). In addition, an event-related potential indicative for suppression (the Distractor Positivity, Pd) was observed following rhythmic but not arrhythmic stimulation, indicating that suppression was boosted by the stimulation. This was also echoed in higher spectral power and intertrial phase coherence of EEG at rhythmically versus arrhythmically stimulated electrode sites, albeit only at the second harmonic (20 Hz), but not at the stimulation frequency. In addition, inverse validity effects were not modulated by rhythmic entrainment congruent with the cue side. Hence, we propose that rhythmic visual stimulation in the alpha range could support suppression, though behavioral evidence remains elusive, in contrast to electrophysiological findings.

Swift attenuation of irrelevant features through feature consistency: Evidence from a capture-probe version of the contingent-capture protocol

In the present two experiments, we explore the possibility of swift attenuation of capture by irrelevant features in the contingent-capture protocol. Some prior research suggests that feature attenuation might be most efficient for fixed, anticipated irrelevant features and that varying irrelevant features from trial to trial can undermine their successful attenuation. Here, we exploited this dependence of attenuation on feature certainty to test if attenuation contributed to contingent-capture effects in a capture-probe version of the contingent-capture protocol. In line with the swift attenuation of irrelevant features, salient but target-dissimilar singleton cues that were consistently coloured diminished recall of probes at their locations. This was in comparison to inconsistently coloured target-dissimilar singleton cues. Nonetheless, probe-recall was still better at target-dissimilar cue locations than at non-singleton locations in the cueing display, indicating attenuation of task-irrelevant features rather than their complete suppression.

Feature-based attentional control for distractor suppression

To investigate whether attentional suppression is merely a byproduct of target facilitation or a result of independent mechanisms for distractor suppression, the present study examined whether attentional suppression takes place when target facilitation hardly occurs using a spatial cueing paradigm. Participants searched for target letters that were not red, i.e., a negative color. On each trial, a target color was randomly chosen among 12 colors to prevent establishing attentional control for target colors and to reduce intertrial priming for target colors. Immediately before a target display, a noninformative spatial cue was presented at one of the possible target locations. The cue was rendered in a negative color, which was to be ignored, to detect targets or the reference color, which was never presented for target and non-target letters. Experiment 1 showed that negative color cues captured attention less than reference color cues, suggesting feature-based attentional suppression. The suppression effect was replicated when the temporal interval between the onsets of the cue and target displays was reduced in Experiments 2 and 3, suggesting proactive suppression. Experiment 3 directly confirmed no attentional control settings for target colors and intertrial priming. These findings suggest that distractor features can guide attention at the pre-attentive stage when target features are not used to attend to targets.

The effect of prevalence on distractor speeded search termination

Visual search can be disrupted by irrelevant salient stimuli. Recently, Moher (Psychological Science, 31(1), 31-42, 2020) found salient distractors to speed search when a target was absent and increase error rates when the target was present. That is, distractors lowered search-quitting thresholds. Nonetheless, the salient distractors Moher used were present on 50% of all trials. Since distractor prevalence has been found to influence search processes more broadly, here, we aimed to test the effect of distractor prevalence on this distractor-quitting threshold effect (QTE). To do so, we conducted two experiments. Experiment 1 compared the performance of individuals in a search task where the target was present on 50% of trials across two distractor-prevalence conditions (25% vs. 75% prevalence). Experiment 2 followed the same procedure, except with a wider probability margin (10% vs. 90% prevalence). In Experiment 1, distractor prevalence did not modulate the QTE. Critically, in Experiment 2, the QTE was modulated. For high-prevalence distractors (90%), a QTE was observed. However, as low-prevalence distractors (10%) did not speed search, no QTE was observed. One potential reason no QTE was observed was because low-prevalence distractors have significantly greater attentional capture, which washed out speeded termination effects.

Pathway-selective optogenetics reveals the functional anatomy of top-down attentional modulation in the macaque visual cortex

Spatial attention represents a powerful top-down influence on sensory responses in primate visual cortical areas. The frontal eye field (FEF) has emerged as a key candidate area for the source of this modulation. However, it is unclear whether the FEF exerts its effects via its direct axonal projections to visual areas or indirectly through other brain areas and whether the FEF affects both the enhancement of attended and the suppression of unattended sensory responses. We used pathway-selective optogenetics in rhesus macaques performing a spatial attention task to inhibit the direct input from the FEF to area MT, an area along the dorsal visual pathway specialized for the processing of visual motion information. Our results show that the optogenetic inhibition of the FEF input specifically reduces attentional modulation in MT by about a third without affecting the neurons' sensory response component. We find that the direct FEF-to-MT pathway contributes to both the enhanced processing of target stimuli and the suppression of distractors. The FEF, thus, selectively modulates firing rates in visual area MT, and it does so via its direct axonal projections.

Terms of debate: Consensus definitions to guide the scientific discourse on visual distraction

Hypothesis-driven research rests on clearly articulated scientific theories. The building blocks for communicating these theories are scientific terms. Obviously, communication - and thus, scientific progress - is hampered if the meaning of these terms varies idiosyncratically across (sub)fields and even across individual researchers within the same subfield. We have formed an international group of experts representing various theoretical stances with the goal to homogenize the use of the terms that are most relevant to fundamental research on visual distraction in visual search. Our discussions revealed striking heterogeneity and we had to invest much time and effort to increase our mutual understanding of each other's use of central terms, which turned out to be strongly related to our respective theoretical positions. We present the outcomes of these discussions in a glossary and provide some context in several essays. Specifically, we explicate how central terms are used in the distraction literature and consensually sharpen their definitions in order to enable communication across theoretical standpoints. Where applicable, we also explain how the respective constructs can be measured. We believe that this novel type of adversarial collaboration can serve as a model for other fields of psychological research that strive to build a solid groundwork for theorizing and communicating by establishing a common language. For the field of visual distraction, the present paper should facilitate communication across theoretical standpoints and may serve as an introduction and reference text for newcomers.

Separate and overlapping mechanisms of statistical regularities and salience processing in the occipital cortex and dorsal attention network

Attention selects behaviorally relevant inputs for in-depth processing. Beside the role of traditional signals related to goal-directed and stimulus-driven control, a debate exists regarding the mechanisms governing the effect of statistical regularities on attentional selection, and how these are integrated with other control signals. Using a visuo-spatial search task under fMRI, we tested the joint effects of statistical regularities and stimulus-driven salience. We found that both types of signals modulated occipital activity in a spatially specific manner. Salience acted primarily by reducing the attention bias towards the target location when associated with irrelevant distractors, while statistical regularities reduced this attention bias when the target was presented at a low probability location, particularly at the lower levels of the visual hierarchy. In addition, we found that both statistical regularities and salience activated the dorsal frontoparietal network. Additional exploratory analyses of functional connectivity revealed that only statistical regularities modulated the inter-regional coupling between the posterior parietal cortex and the occipital cortex. These results show that statistical regularities and salience signals are both spatially represented at the occipital level, but that their integration into attentional processing priorities relies on dissociable brain mechanisms.

Statistical learning of target and distractor spatial probability shape a common attentional priority computation

Converging evidence recently put forward the notion that dedicated neurocognitive mechanisms do exist for the suppression of salient, but irrelevant distractors. Along this line, it is plausible to hypothesize that, in appropriate contexts, experience-dependent forms of attentional learning might selectively induce plastic changes within this dedicated circuitry, thus allowing an independent shaping of priorities at the service of attentional filtering. Conversely, previous work suggested that statistical learning (SL) of both target and distractor spatial probability distributions converge in adjusting only the overall attentional priority of locations: in fact, in the presence of an independent manipulation, either related to the target or to the distractor only, SL induces indirect effects (e.g., changes in filtering efficiency due to an uneven distribution of targets), suggesting that SL-induced plastic changes affect a shared neural substrate. Here we tested whether, when (conflicting) target- and distractor-related manipulations are concurrently applied to the very same locations, dedicated mechanisms might support the selective encoding of spatial priority in relation to the specific attentional operation involved. In three related experiments, human healthy participants discriminated the direction of a target arrow, while ignoring a salient distractor, if present; both target and distractor spatial probability distributions were concurrently manipulated in relation to each single location. Critically, the selection bias produced by the target-related SL was marginally reduced by an adverse distractor contingency, and the suppression bias generated by the distractor-related SL was erased, or even reversed, by an adverse target contingency. Our results suggest that even conflicting target- and distractor-related SL manipulations result in the adjustment of a unique spatial priority computation, likely because the process directly relies on direct plastic alterations of shared spatial priority map(s).

On preventing capture: Does greater salience cause greater suppression?

It has been proposed that salient objects have high potential to disrupt target performance, and so people learn to proactively suppress them, thereby preventing these salient distractors from capturing attention in the future. Consistent with this hypothesis, Gaspar et al. (Proceedings of the National Academy of Sciences, 113(13), 3693-3698, 2016) reported that the PD (believed to index suppression) was larger for high-salient color distractors than for low-salient color distractors. The present study looked for converging evidence that salience triggers suppression using established behavior measures of suppression. Following Gaspar et al., our participants searched for a yellow target circle among nine background circles, which sometimes included one circle with a unique color. The distractor was either high or low in salience with respect to the background circles. The question was whether the high-salient color would be proactively suppressed more strongly than the low-salient color. This was assessed using the capture-probe paradigm. On 33% of trials, probe letters appeared inside colored circles and participants were to report those letters. If high-salient colors are more strongly suppressed, then probe recall accuracy should be lower at locations with the high-salient color than those with the low-salient color. Experiment 1 found no such effect. A similar finding was observed in Experiment 2 after addressing possible floor effects. These findings suggest that proactive suppression is not caused by salience. We propose that the PD reflects not only proactive suppression but also reactive suppression.

The Distractor Positivity Component and the Inhibition of Distracting Stimuli

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 (PD), 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 PD has been used to understand the ability to ignore distracting stimuli. In particular, we outline how the PD 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 PD component. Ultimately, we conclude that the PD 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.

The effects of visual distractors on serial dependence

Attractive serial dependence occurs when perceptual decisions are attracted toward previous stimuli. This effect is mediated by spatial attention and is most likely to occur when similar stimuli are attended at nearby locations. Attention, however, also involves the suppression of distracting information and of spatial locations where distracting stimuli have frequently appeared. Although distractors form an integral part of our visual experience, how they affect the processing of subsequent stimuli is unknown. Here, in two experiments, we tested serial dependence from distractor stimuli during an orientation adjustment task. We interleaved adjustment trials with a discrimination task requiring observers to ignore a peripheral distractor randomly appearing on half of the trials. Distractors were either similar to the adjustment probe (Experiment 1) or differed in spatial frequency and contrast (Experiment 2) and were shown at predictable or random locations in separate blocks. The results showed that the distractor caused considerable attentional capture in the discrimination task, with observers likely using proactive strategies to anticipate distractors at predictable locations. However, there was no evidence that the distractors affected the perceptual stream leading to positive serial dependence. Instead, they left a weak repulsive trace in Experiment 1 and more generally interfered with the effect of the previous adjustment probe in the serial dependence task. We suggest that this repulsive bias may reflect the operation of mechanisms involved in attentional suppression.

Pinging the brain to reveal the hidden attentional priority map using encephalography

Attention has been usefully thought of as organized in priority maps - putative maps of space where attentional priority is weighted across spatial regions in a winner-take-all competition for attentional deployment. Recent work has highlighted the influence of past experiences on the weighting of spatial priority - called selection history. Aside from being distinct from more well-studied, top-down forms of attentional enhancement, little is known about the neural substrates of history-mediated attentional priority. Using a task known to induce statistical learning of target distributions, in an EEG study we demonstrate that this otherwise invisible, latent attentional priority map can be visualized during the intertrial period using a 'pinging' technique in conjunction with multivariate pattern analyses. Our findings not only offer a method of visualizing the history-mediated attentional priority map, but also shed light on the underlying mechanisms allowing our past experiences to influence future behavior.

Distractor suppression does and does not depend on pre-distractor alpha-band activity

Selective attention enhances behaviorally important information and suppresses distracting information. Research on the neural basis of selective attention has largely focused on sensory enhancement, with less focus on sensory suppression. Enhancement and suppression can operate through a push-pull relationship that arises from competitive interactions among neural populations. There has been considerable debate, however, regarding (i) whether suppression can also operate independent of enhancement and (ii) whether neural processes associated with the voluntary deployment of suppression can occur prior to distractor onset. We provide further behavioral and electrophysiological evidence of independent suppression at cued distractor locations while humans performed a visual search task. We specifically utilize two established EEG markers of suppression: alpha power (∼8-15 Hz) and the distractor positivity (P D ). Increased alpha power has been linked with attenuated sensory processing, while the P D -a component of event-related potentials-has been linked with successful distractor suppression. The present results demonstrate that cueing the location of an upcoming distractor speeded responding and led to an earlier onset P D , consistent with earlier suppression due to strategic use of a spatial cue. We further demonstrate that higher pre-distractor alpha power contralateral to distractors was generally associated with successful suppression on both cued and non-cued trials. However, there was no consistent change in alpha power associated with the spatial cue, meaning cueing effects on behavioral and neural measures occurred independent of alpha-related gating of sensory processing. These findings reveal the importance of pre-distractor neural processes for subsequent distractor suppression.

Significance Statement

Selective suppression of distracting information is important for survival, contributing to preferential processing of behaviorally important information. Does foreknowledge of an upcoming distractor's location help with suppression? Here, we recorded EEG while subjects performed a target detection task with cues that indicated the location of upcoming distractors. Behavioral and electrophysiological results revealed that foreknowledge of a distractor's location speeded suppression, thereby facilitating target detection. The results further revealed a significant relationship between pre-stimulus alpha-band activity and successful suppression; however, pre-stimulus alpha-band activity was not consistently lateralized relative to the spatially informative cues. The present findings therefore demonstrate that target detection can benefit from foreknowledge of distractor location in a process that is independent of alpha-related gating of sensory processing.

Target enhancement but not distractor suppression in auditory neural tracking during continuous speech

Selective attention modulates the neural tracking of speech in auditory cortical regions. It is unclear whether this attentional modulation is dominated by enhanced target tracking, or suppression of distraction. To settle this long-standing debate, we employed an augmented electroencephalography (EEG) speech-tracking paradigm with target, distractor, and neutral streams. Concurrent target speech and distractor (i.e., sometimes relevant) speech were juxtaposed with a third, never task-relevant speech stream serving as neutral baseline. Listeners had to detect short target repeats and committed more false alarms originating from the distractor than from the neutral stream. Speech tracking revealed target enhancement but no distractor suppression below the neutral baseline. Speech tracking of the target (not distractor or neutral speech) explained single-trial accuracy in repeat detection. In sum, the enhanced neural representation of target speech is specific to processes of attentional gain for behaviorally relevant target speech rather than neural suppression of distraction.

Spike rates of frontal eye field neurons predict reaction times in a spatial attention task

Which neuronal signal(s) predict reaction times when subjects respond to a target at covertly attended locations? Although recent studies showed that spike rates are not predictive, it remains a highly contested question. Therefore, we record single-unit activity from frontal eye field (FEF) neurons while macaques are performing a covert spatial attention task. We find that the attentional modulation of spike rates of FEF neurons is strongly correlated with behavioral reaction times. Moreover, this correlation already emerges 1 s before target dimming, which triggers the behavioral responses. This prediction of reaction times by spike rates is found in neurons showing attention-dependent enhanced and suppressed activity for targets and distractors, respectively, yet in varying degrees across subjects. Thus, spike rates of FEF neurons can predict reaction times persistently and well before the operant behavior during selective attention tasks. Such long prediction windows will be useful for developing spike-based brain-machine interfaces.

Statistical Learning of Distractor Suppression Downregulates Prestimulus Neural Excitability in Early Visual Cortex

Visual attention is highly influenced by past experiences. Recent behavioral research has shown that expectations about the spatial location of distractors within a search array are implicitly learned, with expected distractors becoming less interfering. Little is known about the neural mechanism supporting this form of statistical learning. Here, we used magnetoencephalography (MEG) to measure human brain activity to test whether proactive mechanisms are involved in the statistical learning of distractor locations. Specifically, we used a new technique called rapid invisible frequency tagging (RIFT) to assess neural excitability in early visual cortex during statistical learning of distractor suppression while concurrently investigating the modulation of posterior alpha band activity (8-12 Hz). Male and female human participants performed a visual search task in which a target was occasionally presented alongside a color-singleton distractor. Unbeknown to the participants, the distracting stimuli were presented with different probabilities across the two hemifields. RIFT analysis showed that early visual cortex exhibited reduced neural excitability in the prestimulus interval at retinotopic locations associated with higher distractor probabilities. In contrast, we did not find any evidence of expectation-driven distractor suppression in alpha band activity. These findings indicate that proactive mechanisms of attention are involved in predictive distractor suppression and that these mechanisms are associated with altered neural excitability in early visual cortex. Moreover, our findings indicate that RIFT and alpha band activity might subtend different and possibly independent attentional mechanisms.SIGNIFICANCE STATEMENT What we experienced in the past affects how we perceive the external world in the future. For example, an annoying flashing light might be better ignored if we know in advance where it usually appears. This ability of extracting regularities from the environment is called statistical learning. In this study, we explore the neuronal mechanisms allowing the attentional system to overlook items that are unequivocally distracting based on their spatial distribution. By recording brain activity using MEG while probing neural excitability with a novel technique called RIFT, we show that the neuronal excitability in early visual cortex is reduced in advance of stimulus presentation for locations where distracting items are more likely to occur.

No evidence for spatial suppression due to across-trial distractor learning in visual search

Previous studies have shown that during visual search, participants are able to implicitly learn across-trial regularities regarding target locations and use these to improve search performance. The present study asks whether such across-trial visual statistical learning also extends to the location of salient distractors. In Experiments 1 and 2, distractor regularities were paired so that a specific distractor location was 100% predictive of another specific distractor location on the next trial. Unlike previous findings that employed target regularities, the current results show no difference in search times between predictable and unpredictable trials. In Experiments 3-5 the distractor location was presented in a structured order (a sequence) for one group of participants, while it was presented randomly for the other group. Again, there was no learning effect of the across-trial regularities regarding the salient distractor locations. Across five experiments, we demonstrated that participants were unable to exploit across-trial spatial regularities regarding the salient distractors. These findings point to important boundary conditions for the modulation of visual attention by statistical regularities and they highlight the need to differentiate between different types of statistical regularities.

Evidence for top-down suppression of negative features in the target feature dimension

While searching for a goal-relevant object, an internal representation of the features necessary to identify the to-be-searched-for object (i.e., target) guides attention towards visual stimuli with matching properties. Recent evidence suggests that features that negatively define a target (i.e., negative features) also bias attentional allocation through top-down suppression. Since humans usually know what to look for, it will rarely, if ever, be the case that a negative feature defines a goal-relevant object alone. Thus, to better understand the relevance of top-down suppression, our participants searched for a target conjunctively defined by a positive (e.g., a blue bar) and a negative feature (e.g., a nonred bar) with both features realized within the same dimension (color in Experiments 1, 3 and 4, orientation in Experiment 2). Experiments 1 and 2 showed that reaction times were slower if cues with a negative feature preceded the target at the same versus a different position (i.e., validly vs. invalidly cued targets), indicating suppression. In contrast, cues with a task-irrelevant different-dimension feature elicited no significant reaction time difference between validly cued and invalidly cued trials. In addition, Experiment 3 showed that while negative cues were top-down suppressed, cues with a positive feature captured attention. This finding indicated that both positive and negative features guide visual attention through capture and suppression, respectively, during the search for a target defined by the presence of one and the absence of another feature from the same dimension. However, suppression seems to apply to the negative and all nontarget features in the task-relevant dimension. This was shown in Experiment 4, in which participants suppressed cues with a task-irrelevant color similarly to cues with a negative color.

Priming of probabilistic attentional templates

Attentional priming has a dominating influence on vision, speeding visual search, releasing items from crowding, reducing masking effects, and during free-choice, primed targets are chosen over unprimed ones. Many accounts postulate that templates stored in working memory control what we attend to and mediate the priming. But what is the nature of these templates (or representations)? Analyses of real-world visual scenes suggest that tuning templates to exact color or luminance values would be impractical since those can vary greatly because of changes in environmental circumstances and perceptual interpretation. Tuning templates to a range of the most probable values would be more efficient. Recent evidence does indeed suggest that the visual system represents such probability, gradually encoding statistical variation in the environment through repeated exposure to input statistics. This is consistent with evidence from neurophysiology and theoretical neuroscience as well as computational evidence of probabilistic representations in visual perception. I argue that such probabilistic representations are the unit of attentional priming and that priming of, say, a repeated single-color value simply involves priming of a distribution with no variance. This "priming of probability" view can be modelled within a Bayesian framework where priming provides contextual priors. Priming can therefore be thought of as learning of the underlying probability density function of the target or distractor sets in a given continuous task.

The mechanisms of selective attention in phenomenal consciousness

In three experiments we investigated the effects of selective attention in iconic memory and fragile-visual short-term memory (VSTM), which have been related to phenomenal consciousness. We used a novel retro-cue paradigm with different delays (early vs late) and object priorities (high vs equal vs low), to investigate (a) attentional costs and benefits and the role of (b) bottom-up factors and (c) fragile-VSTM in feature-based attentional selection. Experiment 1 showed that attentional costs modulate visual maintenance at longer delays, while Experiment 2 showed that by reducing the time exposure of the memory array from 250 ms to 100 ms, as a bottom-up factor, participants were not able to select the objects based on their priorities. Finally, Experiment 3 showed that a pattern mask presented before the transfer in visual working memory, attenuates the overall performance while preserving the priority effect. The implications for phenomenal consciousness before conscious access are discussed.

Task-irrelevant emotional faces impact BOLD responses more for prosaccades than antisaccades in a mixed saccade fMRI task

Cognitive control allows individuals to flexibly and efficiently perform tasks by attending to relevant stimuli while inhibiting distraction from irrelevant stimuli. The antisaccade task assesses cognitive control by requiring participants to inhibit a prepotent glance towards a peripheral stimulus and generate an eye movement to the mirror image location. This task can be administered with various contextual manipulations to investigate how factors such as trial timing or emotional content interact with cognitive control. In the current study, 26 healthy adults completed a mixed antisaccade and prosaccade fMRI task that included task irrelevant emotional faces and gap/overlap timing. The results showed typical antisaccade and gap behavioral effects with greater BOLD activation in frontal and parietal brain regions for antisaccade and overlap trials. Conversely, there were no differences in behavior based on the emotion of the task irrelevant face, but trials with neutral faces had greater activation in widespread visual regions than trials with angry faces, particularly for prosaccade and overlap trials. Together, these effects suggest that a high level of cognitive control and inhibition was required throughout the task, minimizing the impact of the face presentation on saccade behavior, but leading to increased attention to the neutral faces on overlap prosaccade trials when both the task cue (look towards) and emotion stimulus (neutral, non-threatening) facilitated disinhibition of visual processing.

Negative and positive templates: Two forms of cued attentional control

Our ability to control our attention to focus on goal-relevant information is critical for functioning in daily life. In addition to the typical attentional control driven by target enhancement described in most theories of attention, recent research has focused on our ability to use information about distractions maintained in working memory to direct our attention away from known distractors. Using these negative templates can improve the efficiency of attention, much in the same way as enhancing information matching search targets. However, these effects only occur for specific tasks or in specific circumstances. In this review, I will focus on our emerging understanding of the relationship between distractor ignoring from negative templates and target enhancement from positive templates. I will also highlight key remaining questions for further study.

Distractor ignoring is as effective as target enhancement when incidentally learned but not when explicitly cued

Explicit knowledge about upcoming target or distractor features can increase performance in tasks like visual search. However, explicit distractor cues generally result in smaller performance benefits than target cues, suggesting that suppressing irrelevant information is less effective than enhancing relevant information. Is this asymmetry a general principle of feature-based attention? Across four experiments (N = 75 each) we compared the efficiency of target selection and distractor ignoring through either incidental experience or explicit instructions. Participants searched for an orientation-defined target amidst seven distractors-three in the target color and four in another color. In Experiment 1, either targets (Exp. 1a) or distractors (Exp. 1b) were presented more often in a specific color than other possible search colors. Response times showed comparable benefits of learned attention towards (Exp. 1a) and away from (Exp. 1b) the frequent color, suggesting that learned target selection and distractor ignoring can be equally effective. In Experiment 2, participants completed a nearly identical task, only with explicit cues to the target (Exp. 2a) or distractor color (Exp. 2b), inducing voluntary attention. Both target and distractor cues were beneficial for search performance, but distractor cues much less so than target cues, consistent with previous results. Cross-experiment analyses verified that the relative inefficiency of distractor ignoring versus target selection is a unique characteristic of voluntary attention that is not shared by incidentally learned attention, pointing to dissociable mechanisms of voluntary and learned attention to support distractor ignoring.

How do (perceptual) distracters distract?

When a target stimulus occurs in the presence of distracters, decisions are less accurate. But how exactly do distracters affect choices? Here, we explored this question using measurement of human behaviour, psychophysical reverse correlation and computational modelling. We contrasted two models: one in which targets and distracters had independent influence on choices (independent model) and one in which distracters modulated choices in a way that depended on their similarity to the target (interaction model). Across three experiments, participants were asked to make fine orientation judgments about the tilt of a target grating presented adjacent to an irrelevant distracter. We found strong evidence for the interaction model, in that decisions were more sensitive when target and distracter were consistent relative to when they were inconsistent. This consistency bias occurred in the frame of reference of the decision, that is, it operated on decision values rather than on sensory signals, and surprisingly, it was independent of spatial attention. A normalization framework, where target features are normalized by the expectation and variability of the local context, successfully captures the observed pattern of results.

In the real world, visual scenes usually contain many objects. As a consequence, we often have to make perceptual judgments about a specific ‘target’ stimulus in the presence of irrelevant ‘distracter’ stimuli. For instance, when hanging a picture frame, we want to discern whether it is hanging straight, ignoring the surrounding, potentially tilted frames. Laboratory experiments have shown that the presence of distracter stimuli (i.e. other picture frames) makes this type of perceptual judgment less accurate. However, the specific effect distracters have on judgments is controversial. Here, we conducted a series of experiments to compare two alternative theories of distracter influence: one in which distracters compete with targets to determine choices (independent model) and one in which distracters wield a more indirect influence on choices (interaction model). We found evidence for the latter account. Our results suggest distracters affect perceptual decisions by adjusting how sensitive decisions are to the target stimulus.

Do salient abrupt onsets trigger suppression?

Many studies have indicated that abrupt onsets can capture our attention involuntarily. The present study examined whether task-irrelevant onsets trigger strong suppression of their features, to reduce the ability of the onsets to capture attention. We used a capture-probe paradigm with salient abrupt onsets as precues. Participants performed a search task (70% of the trials) with occasional probe tasks mixed in (30% of the trials). In Experiment 1, two irrelevant-color distractors appeared simultaneously with the target, one of which was always precued by the abrupt onset. The question was whether an abrupt onset cue would promote suppression of the correlated color, thereby impeding recall of probe letters at a location with that color. This did not happen. The same result was obtained in Experiment 2, despite removing the target shape from the probe display to minimize floor effects and despite presenting only one distractor color per trial to further strengthen the onset-color association. In Experiment 3, one of the two irrelevant-color distractors abruptly onsetted 50 ms before the other search elements. Despite efforts to promote suppression of the cued distractor color, probe recall accuracy was again similar for the cued and non-cued distractor colors. We conclude that distractor features are suppressed but that making them especially salient does not noticeably enhance this suppression. The suppression mechanism is therefore geared towards helping observers discriminate between target features and distractor features, not towards beating down the most threatening object.

Learned low priority of attention after training to suppress color singleton distractor

Allocating attention to significant events, such as a salient object, is effortless. Our brain is effective on this type of processing because doing so is generally beneficial for survival. However, a salient object could also be distracting and ignoring it costs a large amount of cognitive resource. In the present study, we conducted two behavioral experiments to investigate the effect of learned suppression of a salient color. Particularly, we were interested in the effect of learning in a new task context in which the previously suppressed color was task irrelevant. In Experiment 1, we trained the participants for five days with explicit instruction to suppress a color singleton distractor in a visual search task. We measured the effect of training with a dot probe task before and after the training. Colors in the dot probe task only served as the background and were not associated with the position of the target dot. However, we found that attention was involuntarily biased away from the previously suppressed color. In Experiment 2, the color singleton could either be the target or distractor in the visual search task, making the suppression of the color singleton inefficient for task performance. The results showed no training effect in the dot probe task after this manipulation. These findings provided direct evidence for the learned low priority of attention after training to suppress the color singleton distractor.

Can enhancement and suppression concurrently guide attention? An assessment at the individual level

Background: Although people can pay attention to targets while ignoring distractors, previous research suggests that target enhancement and distractor suppression work separately and independently. Here, we sought to replicate previous findings and re-establish their independence. Methods: We employed an internet-based psychological experiment. We presented participants with a visual search task in which they searched for a specified shape with or without a singleton. We replicated the singleton-presence benefit in search performance, but this effect was limited to cases where the target color was fixed across all trials. In a randomly intermixed probe task (30% of all trials), the participants searched for a letter among colored probes; we used this task to assess how far attention was separately allocated toward the target or distractor dimensions. Results: We found a negative correlation between target enhancement and distractor suppression, indicating that the participants who paid closer attention to target features ignored distractor features less effectively and vice versa. Averaged data showed no benefit from target color or cost from distractor color, possibly because of the substantial differences in strategy across participants. Conclusions: These results suggest that target enhancement and distractor suppression guide attention in mutually dependent ways and that the relative contribution of these components depends on the participants’ search strategy.

Gains and Losses Affect Learning Differentially at Low and High Attentional Load

Prospective gains and losses influence cognitive processing, but it is unresolved how they modulate flexible learning in changing environments. The prospect of gains might enhance flexible learning through prioritized processing of reward-predicting stimuli, but it is unclear how far this learning benefit extends when task demands increase. Similarly, experiencing losses might facilitate learning when they trigger attentional reorienting away from loss-inducing stimuli, but losses may also impair learning by increasing motivational costs or when negative outcomes are overgeneralized. To clarify these divergent views, we tested how varying magnitudes of gains and losses affect the flexible learning of feature values in environments that varied attentional load by increasing the number of interfering object features. With this task design, we found that larger prospective gains improved learning efficacy and learning speed, but only when attentional load was low. In contrast, expecting losses impaired learning efficacy, and this impairment was larger at higher attentional load. These findings functionally dissociate the contributions of gains and losses on flexible learning, suggesting they operate via separate control mechanisms. One mechanism is triggered by experiencing loss and reduces the ability to reduce distractor interference, impairs assigning credit to specific loss-inducing features, and decreases efficient exploration during learning. The second mechanism is triggered by experiencing gains, which enhances prioritizing reward-predicting stimulus features as long as the interference of distracting features is limited. Taken together, these results support a rational theory of cognitive control during learning, suggesting that experiencing losses and experiencing distractor interference impose costs for learning.

Temporal integration of feature probability distributions

Humans are surprisingly good at learning the statistical characteristics of their visual environment. Recent studies have revealed that not only can the visual system learn repeated features of visual search distractors, but also their actual probability distributions. Search times were determined by the frequency of distractor features over consecutive search trials. The search displays applied in these studies involved many exemplars of distractors on each trial and while there is clear evidence that feature distributions can be learned from large distractor sets, it is less clear if distributions are well learned for single targets presented on each trial. Here, we investigated potential learning of probability distributions of single targets during visual search. Over blocks of trials, observers searched for an oddly colored target that was drawn from either a Gaussian or a uniform distribution. Search times for the different target colors were clearly influenced by the probability of that feature within trial blocks. The same search targets, coming from the extremes of the two distributions were found significantly slower during the blocks where the targets were drawn from a Gaussian distribution than from a uniform distribution indicating that observers were sensitive to the target probability determined by the distribution shape. In Experiment 2, we replicated the effect using binned distributions and revealed the limitations of encoding complex target distributions. Our results demonstrate detailed internal representations of target feature distributions and that the visual system integrates probability distributions of target colors over surprisingly long trial sequences.

Selection history and task predictability determine the precision expectations in attentional control

Predictive processing frameworks have demonstrated the central role that prediction plays in a range of cognitive processes including bottom-up and top-down mechanisms of attention control. However, relatively little is understood about how predictive processes interact with the third main determinant of attentional priority - selection history. In this experiment, participants developed a history of either color or shape selection while we observed the impact of these histories in an additional singleton search task using behavioral measures and ERP measures of attentional control. Throughout the experiment, participants were encouraged to predict the upcoming display, but prediction errors were either high or low depending on session. Persistent group differences in our results showed that selection history contributes to the precision weighting of a stimulus, and that this is mediated by overall prediction error. Color-singleton distractors captured attention and required greater suppression when participants had a history of color selection; however, these participants gained large benefits when the upcoming stimuli were highly predictable. We suggest that selection history modulates the precision expectations for a feature in a persistent and implicit way, producing an attentional bias that predictability can help to counteract, but cannot prevent or eliminate entirely.

Benefits from negative templates in easy and difficult search depend on rapid distractor rejection and enhanced guidance

While most research on attentional templates focuses on how attention can be guided toward targets, a growing body of research has been examining our ability to guide attention away from distractors using negative templates. A recent report showed larger reaction time benefits from negative templates during a difficult search task compared to an easy search task. However, it remains unclear what shifts in attentional processing led to these differences in reaction time benefits. In the current study, we tested the predictions of enhanced guidance and rapid rejection as potential explanations for the differential impact of negative templates based on search difficulty. In Experiment 1, we replicated the larger benefits from negative templates in a within-subjects design. In Experiment 2, we use eye tracking to measure the proportion of fixations directed towards target-colored distractors as an index of enhanced guidance and the dwell time on distractors as a measure of rapid rejection. We found more attentional guidance from negative templates in the difficult search condition. In addition, we found larger benefits of rapid rejection from negative templates in the difficult search condition. While we typically focus on templates as a way of guiding attention, these results highlight another key role played by attentional templates: rapid distractor rejection.

Habituation to abrupt-onset distractors with different spatial occurrence probability

Previous studies have shown that abrupt onsets randomly appearing at different locations can be ignored with practice, a result that was interpreted as an instance of habituation. Here we addressed whether habituation of capture can be spatially selective and determined by the rate of onset occurrence at different locations, and whether habituation is achieved via spatial suppression applied at the distractor location. In agreement with the habituation hypothesis, we found that capture attenuation was larger where the onset distractor occurred more frequently, similarly to what has been documented for feature-singleton distractors (the “distractor-location effect”), and that onset interference decreased across trials at both the high- and low-probability distractor locations. By contrast, evidence was inconclusive as to whether distractor filtering was also accompanied by a larger impairment in target processing when it appeared at the more likely distractor location (the “target-location effect”), as instead previously reported for feature-singleton distractors. Finally, here we discuss how and to what extent distractor rejection based on statistical learning and habituation of capture are different, and conclude that the two notions are intimately related, as the Sokolov model of habituation operates by comparing the upcoming sensory input with expectation based on the statistics of previous stimulation.

What to expect where and when: how statistical learning drives visual selection

While the visual environment contains massive amounts of information, we should not and cannot pay attention to all events. Instead, we need to direct attention to those events that have proven to be important in the past and suppress those that were distracting and irrelevant. Experiences molded through a learning process enable us to extract and adapt to the statistical regularities in the world. While previous studies have shown that visual statistical learning (VSL) is critical for representing higher order units of perception, here we review the role of VSL in attentional selection. Evidence suggests that through VSL, attentional priority settings are optimally adjusted to regularities in the environment, without intention and without conscious awareness.

Social attention, memory, and memory-guided orienting change across the menstrual cycle

Numerous studies have shown that perception of emotion and emotional memory vary across the menstrual cycle. However, most of these studies used stimuli that contained not only emotional but also social elements. Importantly, the social cognitive abilities of individuals are as crucial as emotional abilities for danger avoidance and recruitment of allies. Therefore, the issue that natural hormonal fluctuations may affect emotion processing should be revisited. To investigate whether the effects of the menstrual cycle are emotion-specific or can also be attributed to social information processing, the present study examined social attention across the menstrual cycle in three tasks-visual search, memory, and memory-guided orienting-with a combination of behavioral and eye-tracking measures. We used images of people standing upright with neutral emotion as social distractors and everyday objects with physical properties matched as non-social distractors. Thirty-six healthy women without hormone use and with stable menstrual cycles of 26 - 30 days participated in the three tasks in the late follicular phase (FP) and mid-luteal phase (LP), respectively. During visual search, participants were asked to search for targets accompanied by social or non-social distractors in complex scenes. Social attentional bias, as evidenced by longer search times and shorter gaze behaviors for targets with social distractors, was found in the FP but not in the LP. In the following memory task, memory accuracy for targets was higher in the FP than in the LP, and the memory for targets with social distractors was more precise in both phases. Finally, in the orienting task, targets in social scenes were detected more slowly than in non-social scenes in LP. Taken together, these findings point to the interplay between social attention, memory, and memory-oriented attention and reveal the distinct processing pathways for social information in the FP and LP. The underlying mechanisms from an evolutionary perspective and from behavioral and neural basis were discussed.

Endogenous control is insufficient for preventing attentional capture in children and adults

Adults are known to have developed the ability to selectively focus their attention in a goal-driven (endogenous) manner but it is less clear at what stage in development (5-6 & 9-11 years) children can endogenously control their attention and whether they behave similarly to adults when managing distractions. In this study we administered a child-adapted cued visual search task to three age-groups: five- to six-year-olds (N = 45), nine- to eleven-year-olds (N = 42) and adults (N = 42). Participants were provided with a cue which either guided their attention towards or away from an upcoming target. On some trials, a singleton distracter was presented which participants needed to ignore. Participants completed three conditions where the cues were: 1) usually helpful (High Predictive), 2) usually unhelpful (Low Predictive) and 3) never helpful (Baseline) in guiding attention towards the target. We found that endogenous cue-utilisation develops with increasing age. Overall, nine- to eleven-year-olds and adults, but not five- to six-year-olds, utilised the endogenous cues in the High Predictive condition. However, all age-groups were unable to ignore the singleton distracter even when using endogenous control. Moreover, we found better cue-maintenance ability was related to poorer distracter-inhibition ability in early-childhood, but these skills were no longer related further on in development. We conclude that overall endogenous control is still developing in early-childhood, but an adult-like form of this skill has been acquired by mid-childhood. Furthermore, endogenous cue-utilisation was shown as insufficient for preventing attentional capture in both children and adults.

Ten simple rules to study distractor suppression

Distractor suppression refers to the ability to filter out distracting and task-irrelevant information. Distractor suppression is essential for survival and considered a key aspect of selective attention. Despite the recent and rapidly evolving literature on distractor suppression, we still know little about how the brain suppresses distracting information. What limits progress is that we lack mutually agreed upon principles of how to study the neural basis of distractor suppression and its manifestation in behavior. Here, we offer ten simple rules that we believe are fundamental when investigating distractor suppression. We provide guidelines on how to design conclusive experiments on distractor suppression (Rules 1-3), discuss different types of distractor suppression that need to be distinguished (Rules 4-6), and provide an overview of models of distractor suppression and considerations of how to evaluate distractor suppression statistically (Rules 7-10). Together, these rules provide a concise and comprehensive synopsis of promising advances in the field of distractor suppression. Following these rules will propel research on distractor suppression in important ways, not only by highlighting prominent issues to both new and more advanced researchers in the field, but also by facilitating communication between sub-disciplines.

Visual Distraction Disrupts Category-tuned Attentional Filters in Ventral Visual Cortex

Our behavioral goals shape how we process information via attentional filters that prioritize goal-relevant information, dictating both where we attend and what we attend to. When something unexpected or salient appears in the environment, it captures our spatial attention. Extensive research has focused on the spatiotemporal aspects of attentional capture, but what happens to concurrent nonspatial filters during visual distraction? Here, we demonstrate a novel, broader consequence of distraction: widespread disruption to filters that regulate category-specific object processing. We recorded fMRI while participants viewed arrays of face/house hybrid images. On distractor-absent trials, we found robust evidence for the standard signature of category-tuned attentional filtering: greater BOLD activation in fusiform face area during attend-faces blocks and in parahippocampal place area during attend-houses blocks. However, on trials where a salient distractor (white rectangle) flashed abruptly around a nontarget location, not only was spatial attention captured, but the concurrent category-tuned attentional filter was disrupted, revealing a boost in activation for the to-be-ignored category. This disruption was robust, resulting in errant processing-and early on, prioritization-of goal-inconsistent information. These findings provide a direct test of the filter disruption theory: that in addition to disrupting spatial attention, distraction also disrupts nonspatial attentional filters tuned to goal-relevant information. Moreover, these results reveal that, under certain circumstances, the filter disruption may be so profound as to induce a full reversal of the attentional control settings, which carries novel implications for both theory and real-world perception.

Ten simple rules to study distractor suppression

Distractor suppression refers to the ability to filter out distracting and task-irrelevant information. Distractor suppression is essential for survival and considered a key aspect of selective attention. Despite the recent and rapidly evolving literature on distractor suppression, we still know little about how the brain suppresses distracting information. What limits progress is that we lack mutually agreed upon principles of how to study the neural basis of distractor suppression and its manifestation in behavior. Here, we offer ten simple rules that we believe are fundamental when investigating distractor suppression. We provide guidelines on how to design conclusive experiments on distractor suppression (Rules 1–3), discuss different types of distractor suppression that need to be distinguished (Rules 4–6), and provide an overview of models of distractor suppression and considerations of how to evaluate distractor suppression statistically (Rules 7–10). Together, these rules provide a concise and comprehensive synopsis of promising advances in the field of distractor suppression. Following these rules will propel research on distractor suppression in important ways, not only by highlighting prominent issues to both new and more advanced researchers in the field, but also by facilitating communication between sub-disciplines.

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Distractor suppression is the ability to filter out irrelevant information.

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At present, we know little about how the brain suppresses distraction.

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We offer ten rules that are fundamental when investigating distractor suppression.

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Following the rules will propel research and foster interaction between disciplines.

Inhibition continues to guide search under concurrent visual working memory load

It is well known that attention can be automatically attracted to salient items. However, recent studies show that it is possible to avoid distraction by a salient item (with a known feature), leading to facilitated search. This article tests a proposed mechanism for distractor inhibition: that a mental representation of the distractor feature held in visual working memory (VWM) allows attention to be guided away from the distractor. We tested this explanation by examining color-based inhibition in visual search for a shape target with and without VWM load. In Experiment 1 the presence of a distractor facilitated visual search under low and high VWM loads, as reflected in faster response times when the distractor was present (compared to absent), and in fewer eye movements to the salient distractor than the non-target items. However, the eye movement inhibition effect was noticeably weakened in the load conditions. Experiment 2 explored further, to distinguish between inhibition of the distractor color and activation of the (irrelevant) target color. Intermittently presenting single-color search trials that contained only either a target, distractor or a neutral-colored singleton revealed that the distractor color attracted attention less than the neutral color with and without VWM load. The target color, however, only attracted attention more than neutral colors under no load, whereas a VWM load completely eliminated this effect. This suggests that although VWM plays a role in guiding attention to the (irrelevant) target color, distractor-feature inhibition can operate independently.

Memory precision for salient distractors decreases with learned suppression

Attention operates as a cognitive gate that selects sensory information for entry into memory and awareness (Driver, 2001, British Journal of Psychology, 92, 53-78). Under many circumstances, the selected information is task-relevant and important to remember, but sometimes perceptually salient nontarget objects will capture attention and enter into awareness despite their irrelevance (Adams & Gaspelin, 2020, Attention, Perception, & Psychophysics, 82[4], 1586-1598). Recent studies have shown that repeated exposures with salient distractor will diminish their ability to capture attention, but the relationship between suppression and later cognitive processes such as memory and awareness remains unclear. If learned attentional suppression (indicated by reduced capture costs) occurs at the sensory level and prevents readout to other cognitive processes, one would expect memory and awareness to dimmish commensurate with improved suppression. Here, we test this hypothesis by measuring memory precision and awareness of salient nontargets over repeated exposures as capture costs decreased. Our results show that stronger learned suppression is accompanied by reductions in memory precision and confidence in having seen a color singleton at all, suggesting that such suppression operates at the sensory level to prevent further processing of the distractor object.

Is Statistical Learning of a Salient Distractor's Color Implicit, Inflexible and Distinct From Inter-Trial Priming?

Being able to overcome distraction by salient distractors is critical in order to allocate our attention efficiently. Previous research showed that observers can learn to ignore salient distractors endowed with some regularity, such as a high-probability location or feature - a phenomenon known as distractor statistical learning. Unlike goal-directed attentional guidance, the bias induced by statistical learning is thought to be implicit, long-lasting and inflexible. We tested these claims with regard to statistical learning of distractor color in a high-power (N = 160) pre-registered experiment. Participants searched for a known-shape singleton target and a color singleton distractor, when present, appeared most often in one color during the learning phase, but equally often in all possible colors during the extinction phase. We used a sensitive measure of participants' awareness of the probability manipulation. The awareness test was administered after the extinction phase for one group, and after the leaning phase for another group - which was informed that the probability imbalance would be discontinued in the upcoming extinction phase. Participants learned to suppress the high-probability distractor color very fast, an effect partly due to intertrial priming. Crucially, there was only little evidence that the bias survived during extinction. Awareness of the manipulation was associated with reduced color suppression, suggesting that the bias was implicit. Finally, results showed that the awareness test was more sensitive when administered early vs. late. We conclude that learnt color suppression is an implicit bias that emerges and decays rapidly, and discuss the methodological implications of our findings.

Stimulus novelty and emotionality interact in the processing of visual distractors

Novel distractors are prioritized for attentional selection. When distractors also convey emotional content, they divert attention from the primary task more than neutral stimuli do. In the present study, while participants were engaged in a central task, we examined the impact of peripheral distractors that varied for emotional content and novelty. Results showed that emotional interference on reaction times completely habituated with repetition and promptly recovered with novelty. The enhanced LPP for emotional pictures was attenuated by repetitions and, interestingly, stimulus novelty only affected emotional, but not neutral distractors, in both the RTs and LPP. Alpha-ERD was similarly reduced for repeated emotional and neutral distractors. Altogether, these findings suggest that the impact of peripheral distractors can be attenuated through a non-strategic learning mechanism mediated by mere stimulus repetition, which is fine-tuned to detect changes in emotional distractors only, supporting the hypothesis that novelty and emotion share the same motivational circuits.

Selective attention involves a feature-specific sequential release from inhibitory gating

Selective attention is a fundamental cognitive mechanism that allows our brain to preferentially process relevant sensory information, while filtering out distracting information. Attention is thought to flexibly gate the communication of irrelevant information through top-down alpha-rhythmic (8-12 Hz) functional connections, which influence early visual processing. However, the dynamic effects of top-down influence on downstream visual processing remain unknown. Here, we used electroencephalography to investigate local and network effects of selective attention while subjects attended to distinct features of identical stimuli. We found that attention-related changes in the functional brain network organization emerge shortly after stimulus onset, accompanied by an overall decrease of functional connectivity. Signatures of attentional selection were evident from a sequential release from alpha-band parietal gating in feature-selective areas. The directed connectivity paths and temporal evolution of this release from gating were consistent with the sensory effect of each feature, providing a neural basis for how visual processing quickly prioritizes relevant information in functionally specialized areas.