Singleton Distractor Research Articles

Working memory load does not interfere with distractor suppression in the additional singleton task.

Over the last decade, the additional singleton task has been widely used to study visual statistical learning. In this paradigm, participants are instructed to find a target while ignoring a series of distractors. In some trials, a salient singleton distractor is added to the search display, making the task more difficult. However, if the singleton appears more frequently in one particular location of the display, participants eventually learn to suppress attention towards this location. It has been suggested that this type of learning is probably implicit and independent of working memory (WM) resources. To our knowledge, only one study has explored the impact of WM in suppression effect (Gao & Theeuwes, Psychonomic Bulletin & Review, 27, 96-104, 2020). However, there are reasons to suspect that the amount and type of WM load used in that study may have been suboptimal to detect any effects on distractor suppression. The aim of the present study was to explore the impact of WM load on distractor suppression addressing these issues. Contrary to our expectations, our results confirm that this type of learning is indeed highly resilient even to strong manipulations of WM load.

Transfer of statistical learning between tasks.

Recent studies have shown that observers can learn to suppress locations in the visual field with a high distractor probability. Here, we investigated whether this learned suppression resulting from a spatial distractor imbalance transfers to a completely different search task that does not contain any distractors. Observers performed the additional singleton task and learned to suppress the location that was likely to contain a color singleton distractor. Within a block, the additional singleton task would randomly switch to a T-among-L task where observers searched in parallel (Experiment 1) or serially (Experiment 2) for a T among Ls. The upcoming search was either unpredictable (Experiment 1/2A) or cued (Experiment 1/2B). The results show that there was transfer of learning from one to the other task as the learned suppression stayed in place after the switch regardless of whether the T-among-L task was performed via parallel or serial search. Moreover, cueing that the task would switch had no effect on performance. The current findings indicate that implicit learned biases are rather inflexible and remain in place even when the task and the required search strategy are dramatically different and even when participants can anticipate that a change in the search required is imminent. This transfer of the suppression to a different task is consistent with the notion that suppression is proactively applied. Because the location is already suppressed proactively, that is, before display onset, regardless which display and task is presented, the suppressed location competes less for attention than all other locations. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Object-based suppression in target search but not in distractor inhibition.

The present study investigated the effect of object representation on attentional priority regarding distractor inhibition and target search processes while the statistical regularities of singleton distractor location were biased. A color singleton distractor appeared more frequently at one of six stimulus locations, called the 'high-probability location,' to induce location-based suppression. Critically, three objects were presented, each of which paired two adjacent stimuli in a target display by adding background contours (Experiment 1) or using perceptual grouping (Experiments 2 and 3). The results revealed that attention capture by singleton distractors was hardly modulated by objects. In contrast, target selection was impeded at the location in the object containing the high-probability location compared to an equidistant location in a different object. This object-based suppression in target selection was evident when object-related features were parts of task-relevant features. These findings suggest that task-irrelevant objects modulate attentional suppression. Moreover, different features are engaged in determining attentional priority for distractor inhibition and target search processes.

Testing the contributions of proactive target and distractor templates in visual search performance

ABSTRACT When searching for objects with particular visual features, performance is sometimes improved by the presence of a salient colour distractor, such as a red item among green objects. Attention to such distractors is thought to be suppressed when the visual system expects their specific features (e.g., redness), but a complication with this view is that distractor expectancies are generally accompanied by anticipated target features, with their own associated attentional facilitation. We tested the role of these mechanisms by separately manipulating the colour specificity of salient distractors and of targets, and thus the ability to build up feature-specific templates for each type of search item. Experiment 1 employed singleton distractors appearing in unpredictable colours, preventing the formation of a feature-specific suppression template. Nevertheless, evidence of suppression was unchanged, suggesting that it does not require a fixed, predictable distractor. In Experiment 2, the singleton colour remained fixed while the target colour varied. Without a constant target colour, markers of singleton suppression were effectively abolished. The pattern of results suggests that observed suppression effects are largely driven by global enhancement of the expected target colour, possibly in combination with a second-order suppression mechanism that is not dependent on specific distractor features.

How we learn to ignore singleton distractors: Suppressing saliency signals or specific features?

ABSTRACT Salient visual information can sometimes capture attention despite our goals. However, there are several ways we can minimize or eliminate such distraction. One such way is learned distractor rejection, in which we increasingly ignore salient, irrelevant distractors across repeated exposures. Here, we probe the mechanism underlying this learned rejection. What must be learned about the distractor to promote effective ignoring? Specifically, is feature rejection, alone, sufficient to ignore salient distractors, or do the items' saliency signals need to also be rejected? We used a modified version of the learned distractor rejection paradigm (Vatterott & Vecera, 2012) in which participants viewed training blocks containing either a salient singleton distractor or three non-salient “tripleton” distractors, followed by test blocks in which the distractor shared a feature (color) with the corresponding training blocks, but was always salient. Results revealed unexpected difficulties in replicating learned distractor rejection, suggesting the true effect size may be smaller than initially reported. With respect to our main objective, we found similar attenuation of singleton presence costs in the test blocks regardless of whether they followed singleton or tripleton training blocks. These results show that experience in rejecting saliency signals is not a requirement of learned distractor rejection.

Relative saliency affects attentional capture and suppression of color and face singleton distractors: evidence from event-related potential studies.

Prior research has yet to fully elucidate the impact of varying relative saliency between target and distractor on attentional capture and suppression, along with their underlying neural mechanisms, especially when social (e.g. face) and perceptual (e.g. color) information interchangeably serve as singleton targets or distractors, competing for attention in a search array. Here, we employed an additional singleton paradigm to investigate the effects of relative saliency on attentional capture (as assessed by N2pc) and suppression (as assessed by PD) of color or face singleton distractors in a visual search task by recording event-related potentials. We found that face singleton distractors with higher relative saliency induced stronger attentional processing. Furthermore, enhancing the physical salience of colors using a bold color ring could enhance attentional processing toward color singleton distractors. Reducing the physical salience of facial stimuli by blurring weakened attentional processing toward face singleton distractors; however, blurring enhanced attentional processing toward color singleton distractors because of the change in relative saliency. In conclusion, the attentional processes of singleton distractors are affected by their relative saliency to singleton targets, with higher relative saliency of singleton distractors resulting in stronger attentional capture and suppression; faces, however, exhibit some specificity in attentional capture and suppression due to high social saliency.

Contextual uncertainty determines early attentional orienting in visual selection

ABSTRACT Our attention can be inadvertently captured by irrelevant or distracting stimuli. Past work has shown that knowledge about the search context in which targets and distractors occur, such as where distractors often occur, can greatly reduce attentional capture. In this study, we set out to show that uncertainty about this context (or contextual variability) is another critical determinant of attentional capture by physically salient distractors. Specifically, in three (preregistered) capture-probe experiments (n =288, n = 114, n = 114), we manipulated singleton distractor location and context uncertainty separately from set size. We found that rendering the distractor location less variable did not affect attentional capture. However, when contextual uncertainty was reduced, by keeping parts of the search display fixed across trials or by exposing participants to a restricted set of search configurations, attentional capture disappeared. Our findings support the notion that contextual uncertainty is a critical factor determining whether salient distractors capture attention.

Retinal eccentricity modulates saliency-driven but not relevance-driven visual selection.

Where we move our eyes during visual search is controlled by the relative saliency and relevance of stimuli in the visual field. However, the visual field is not homogeneous, as both sensory representations and attention change with eccentricity. Here we present an experiment investigating how eccentricity differences between competing stimuli affect saliency- and relevance-driven selection. Participants made a single eye movement to a predefined orientation singleton target that was simultaneously presented with an orientation singleton distractor in a background of multiple homogenously oriented other items. The target was either more or less salient than the distractor. Moreover, each of the two singletons could be presented at one of three different retinal eccentricities, such that both were presented at the same eccentricity, one eccentricity value apart, or two eccentricity values apart. The results showed that selection was initially determined by saliency, followed after about 300 ms by relevance. In addition, observers preferred to select the closer over the more distant singleton, and this central selection bias increased with increasing eccentricity difference. Importantly, it largely emerged within the same time window as the saliency effect, thereby resulting in a net reduction of the influence of saliency on the selection outcome. In contrast, the relevance effect remained unaffected by eccentricity. Together, these findings demonstrate that eccentricity is a major determinant of selection behavior, even to the extent that it modifies the relative contribution of saliency in determining where people move their eyes.

MECHANISMS OF ATTENTIONAL CONTROL AND SUPPRESSION IN AGING

Abstract Attentional control plays a crucial role in our daily lives by allowing our brains to selectively process relevant information while filtering out task-irrelevant distractions. Due to aging, older adults have demonstrated a heightened propensity to be more distractible. This decreased ability to regulate attention has been attributed to an inability to inhibit task-irrelevant salient stimuli. However, the specific mechanisms that underlie this age-related alteration remain unclear. In this study, we utilized a visual search paradigm that directly measures mechanisms of attentional suppression to test our hypothesis that older adults demonstrate reduced capabilities to suppress task-irrelevant information. Young adults (aged 18-35) and older adults (aged 50-80) were tasked to utilize goal-directed attentional control by fixating at a specific target shape. Critically, in some trials, individuals were exposed to a salient color shape that acted as a singleton distractor. While young adults show the ability to suppress attentional allocation to this salient distractor in this paradigm, we hypothesized that older adults would demonstrate attentional capture by this salient distractor. Our findings revealed that older adults made significantly fewer first-fixations towards the target, demonstrating a marked impairment with goal-directed attentional control. Surprisingly, older adults still made fewer fixations toward the distractor in comparison to non-targets, demonstrating that older adults sustained the ability to suppress irrelevant distractors. These findings raise important questions on the mechanisms that underlie increased distractibility in aging and oculomotor attentional control.

Can cognitive training capitalise on near transfer effects? Limited evidence of transfer following online inhibition training in a randomised-controlled trial.

Despite early promise, cognitive training research has failed to deliver consistent real-world benefits and questions have been raised about the experimental rigour of many studies. Several meta-analyses have suggested that there is little to no evidence for transfer of training from computerised tasks to real-world skills. More targeted training approaches that aim to optimise performance on specific tasks have, however, shown more promising effects. In particular, the use of inhibition training for improving shoot/don't-shoot decision-making has returned positive far transfer effects. In the present work, we tested whether an online inhibition training task could generate near and mid-transfer effects in the context of response inhibition tasks. As there has been relatively little testing of retention effects in the literature to date, we also examined whether any benefits would persist over a 1-month interval. In a pre-registered, randomised-controlled trial, participants (n = 73) were allocated to either an inhibition training programme (six training sessions of a visual search task with singleton distractor) or a closely matched active control task (that omitted the distractor element). We assessed near transfer to a Flanker task, and mid-transfer to a computerised shoot/don't-shoot task. There was evidence for a near transfer effect, but no evidence for mid-transfer. There was also no evidence that the magnitude of training improvement was related to transfer task performance. This finding adds to the growing body of literature questioning the effectiveness of cognitive training. Given previous positive findings, however, there may still be value in continuing to explore the extent to which cognitive training can capitalise on near or mid-transfer effects for performance optimisation.

Different prioritization states of working memory representations affect visual searches: Evidence from an event-related potential study

Previous evidence has shown that the contents of working memory (WM) can bias visual selection. However, not much is known about how WM effects change when the WM representation is held in different prioritization states. Here, we investigated this problem using event-related potentials. Subjects maintained two colors in WM while performing a search task. One of the colors was retro-cued, indicating that it was 80 % likely to be the target of the memory test. During the search display, one of the distractors was a salient color singleton, and this singleton distractor could carry the same color as the cued WM representation, the uncued WM representation, or be irrelevant to the memory content. Behaviorally, the memory test performance was found to be better for the cued color than for the uncued color, and we observed lower search accuracy (ACC) and longer search reaction time (RT) when the singleton distractor matched the cued WM representation than when it matched an uncued or an irrelevant WM representation. Event-related potential (ERP) data showed that the P3 amplitude of cue-color distractor conditions was smaller than that of uncued-color distractor conditions and irrelevant-color distractor conditions. These findings clearly indicate that prioritizing an item for enhanced representational quality enables the item to bias attention to a greater extent.

How we learn to ignore singleton distractors: Suppressing saliency signals or specific features?

How we learn to ignore singleton distractors: Suppressing saliency signals or specific features?

The role of posterior parietal cortex and medial prefrontal cortex in distraction and mind-wandering

Distraction reflects a drift of attention away from the task at hand towards task-irrelevant external or internal information (mind-wandering). The right posterior parietal cortex (PPC) and the medial prefrontal cortex (mPFC) are known to mediate attention to external information and mind-wandering, respectively, but it is not clear whether they support each process selectively or rather they play similar roles in supporting both. In this study, participants performed a visual search task including salient color singleton distractors before and after receiving cathodal (inhibitory) transcranial direct current stimulation (tDCS) to the right PPC, the mPFC, or sham tDCS. Thought probes assessed the intensity and contents of mind-wandering during visual search. The results show that tDCS to the right PPC but not mPFC reduced the attentional capture by the singleton distractor during visual search. tDCS to both mPFC and PPC reduced mind-wandering, but only tDCS to the mPFC specifically reduced future-oriented mind-wandering. These results suggest that the right PPC and mPFC play a different role in directing attention towards task-irrelevant information. The PPC is involved in both external and internal distraction, possibly by mediating the disengagement of attention from the current task and its reorienting to salient information, be this a percept or a mental content (mind-wandering). By contrast, the mPFC uniquely supports mind-wandering, possibly by mediating the endogenous generation of future-oriented thoughts capable to draw attention inward, away from ongoing activities.

Little engagement of attention by salient distractors defined in a different dimension or modality to the visual search target.

Singleton distractors may inadvertently capture attention, interfering with the task at hand. The underlying neural mechanisms of how we prevent or handle distractor interference remain elusive. Here, we varied the type of salient distractor introduced in a visual search task: the distractor could be defined in the same (shape) dimension as the target, a different (color) dimension, or a different (tactile) modality (intra-dimensional, cross-dimensional, and, respectively, cross-modal distractor, all matched for physical salience); and besides behavioral interference, we measured lateralized electrophysiological indicators of attentional selectivity (the N2pc, Ppc, PD , CCN/CCP, CDA, and cCDA). The results revealed the intra-dimensional distractor to produce the strongest reaction-time interference, associated with the smallest target-elicited N2pc. In contrast, the cross-dimensional and cross-modal distractors did not engender any significant interference, and the target-elicited N2pc was comparable to the condition in which the search display contained only the target singleton, thus ruling out early attentional capture. Moreover, the cross-modal distractor elicited a significant early CCN/CCP, but did not influence the target-elicited N2pc, suggesting that the tactile distractor is registered by the somatosensory system (rather than being proactively suppressed), without, however, engaging attention. Together, our findings indicate that, in contrast to distractors defined in the same dimension as the target, distractors singled out in a different dimension or modality can be effectively prevented to engage attention, consistent with dimension- or modality-weighting accounts of attentional priority computation.

Delayed onsets are not necessary for generating distractor quitting thresholds effects in visual search.

Salient distractors lower quitting thresholds in visual search. That is, when searching for the presence of a target among filler items, a large heterogeneously coloured distractor presented at a delayed onset produces quick target-absent judgements and increased target-present errors. The aim of the current study was to explore if the timing of the salient distractor modulates this Quitting Threshold Effect (QTE). In Experiment 1, participants completed a target detection search task in the presence or absence of a salient singleton distractor that either appeared simultaneously with other search items or appeared at a delayed onset (i.e., 100 ms or 250 ms after other array items appeared). In Experiment 2, a similar method was used, except that the salient singleton distractor appeared simultaneously, 100 ms before, or 100 ms after the other array items. Across both experiments, we observed robust distractor QTEs. Regardless of their onset, salient distractors decreased target-absent search speeds and increased target-present error rates. In all, the present findings suggest that delayed onsets are not required for lowered quitting thresholds in visual search.

Reward history modulates attention based on feature relationship.

Prioritizing attention to reward-predictive items is critical for survival, but challenging because these items rarely appear in the same feature or within the same environment. However, whether attention selection can be adaptively tuned to items that matched the context-dependent, relative feature of previously rewarded items remains largely unknown. In four experiments (N = 40 per experiment), we trained participants to learn the color-reward association and then adopted visual search tasks in which the color of a singleton distractor matched either the feature value (e.g., red or yellow) or feature relationship (i.e., redder or yellower) of previously rewarded colors. We consistently found enhanced attentional capture by a singleton distractor when it was relationally matched to the high reward compared with the low reward relationship, in addition to observing the typical effect of learned value on singletons matching the previously rewarded colors. Our findings provide novel evidence for the flexibility of value-driven attention via feature relationship, which is particularly useful given the changeable sensory inputs in real-world searches. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Learned spatial suppression is not always proactive.

Learning to ignore distractors is critical for navigating the visual world. Research has suggested that a location frequently containing a salient distractor can be suppressed. How does such suppression work? Previous studies provided evidence for proactive suppression, but methodological limitations preclude firm conclusions. We sought to overcome these limitations with a new search-probe paradigm. On search trials, participants searched for a shape oddball target while a salient color singleton distractor frequently appeared in a high-probability location. On randomly interleaved probe trials, participants discriminated the orientation of a tilted bar presented briefly at one of the search locations, allowing us to index the spatial distribution of attention at the moment the search would have begun. Results on search trials replicated previous findings: reduced attentional capture when a salient distractor appeared in the high-probability location. However, critically, probe discrimination was no different at the high-probability and low-probability locations. We increased the incentive to ignore the high-probability location in Experiment 2 and found, strikingly, that probe discrimination accuracy was greater at the high-probability location. These results suggest that the high-probability location was initially selected before being suppressed, consistent with a reactive mechanism. Overall, the accuracy probe procedure demonstrates that learned spatial suppression is not always proactive, even when response time metrics seem consistent with such an inference. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Global enhancement of target color-not proactive suppression-explains attentional deployment during visual search.

The current study touches on a central debate in the area of attention: how the human brain handles distraction by salient stimuli. The idea of proactive suppression proposes a new fundamental perceptual mechanism to resolve this question, whereby attentional capture by a task-irrelevant salient distractor can be preempted through top-down inhibitory mechanisms. In this study, we replicate empirical effects underlying this claim, but show that they are better explained by an alternative mechanism, global target-feature enhancement. Identical to original studies using a capture-probe dual-task design, observers recalled fewer letters superimposed upon color singleton distractors, relative to other irrelevant search items (fillers). However, given that fillers (but not singleton distractors) always matched the color of the target, this effect could have been due to global featural attention to the target color rather than suppression of the singleton distractor. After manipulating the color of fillers such that they no longer matched the target color, probe recall associated with these was reduced, causing the relative "suppression" of singleton distractors to be abolished. We then manipulated the color similarity of targets and fillers, and found that filler probe recall was graded as a function of this color similarity, even within a single search context. This strongly suggests that increased attention to fillers due to global target color enhancement underlies the difference in attention among distractor items, not proactive distractor suppression. In contrast with feature enhancement and reactive suppression, the proposed proactive suppression mechanism still lacks convincing behavioral evidence. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Distractor's salience does not determine feature suppression: A commentary on Wang and Theeuwes (2020).

There is ongoing debate as to whether distraction by salient irrelevant objects can be avoided by suppressing their salient features. Lamy suggested that a central reason for this stalemate is methodological: researchers often base their conclusions on whether the presence of the salient distractor yields net interference (interpreted as capture) or benefit (interpreted as suppression), instead of investigating how manipulating inhibitory suppression modulates these effects. Here, we validate this observation by revisiting Wang and Theeuwes' findings showing that a color singleton distractor produced a net cost with dense search displays and a net benefit with sparse displays. They concluded that only mildly salient distractors can be suppressed. In two experiments, we orthogonally manipulated distractor salience and feature-based suppression. Participants searched for a shape and a color singleton was sometimes present. Search displays were either sparse or dense and the singleton's color changed on each block. Distractor feature-based suppression was measured as a reduction in distractor interference in the second relative to the first half of each block. We replicated Wang and Theeuwes' findings but invalidated their interpretation by showing that participants learned to suppress the color singleton equally well when displays were sparse and when they were dense. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Feature-blind attentional suppression of salient distractors.

A recent paper has reported, for the first time, that people are capable of suppressing salient singleton distractors of unknown color if the search task requires them to search for the most prevalent of several shapes in the display. We identify here several potential limitations of the earlier findings. In particular, in the reported experiments, the likelihood of a salient distractor was higher than what is typically studied, the distractor object was similar in shape to the relevant objects, only two colors were studied, the distractor was consistently a fixed shape, and the distractor was always a unique shape different from the search targets. Each of these limitations leaves open some questions about the generality of the findings. We address each of the concerns here, and show, in five experiments, that the ability to suppress distractors of unknown color is a robust finding that is not compromised by the potential limitations identified. When searching for the most prevalent of several shapes in a display, people can indeed suppress capture by otherwise-salient color singleton distractors even when their color is not known in advance (i.e., in a feature-blind manner), facilitating efficient search. The experiments confirm the ability to suppress visual elements based on second-order (e.g., a unique color) or global salience information, and not merely based on first-order (e.g., a specific color) information.