Singleton Detection Mode Research Articles

The proactive and reactive mechanisms of learned spatial suppression.

Selection history refers to the notion that previous allocations of attention or suppression have the potential to elicit lingering and enduring selection biases that are isolated from goal-driven or stimulus-driven attention. However, in the singleton detection mode task, manipulating the selection history of distractors cannot give rise to pure proactive inhibition. Therefore, we employed a combination of a working memory task and a feature search mode task, simultaneously recording cortical activity using EEG, to investigate the mechanisms of suppression guided by selection history. The results from event-related potential and reaction times showed an enhanced inhibitory performance when the distractor was presented at the high-probability location, along with instances where the target appeared at the high-probability location of distractors. These findings demonstrate that a generalized proactive inhibition bias is learned and processed independent of cognitive resources, which is supported by selection history. In contrast, reactive rejection toward the low-probability location was evident through the Pd component under varying cognitive resource conditions. Taken together, our findings indicated that participants learned proactive inhibition when the distractor was at the high-probability location, whereas reactive rejection was involved at low-probability location.

Handling distractor interference in mixed and fixed search

ABSTRACT When searching for a target, humans can reduce interference from a colour distractor by using different strategies, such as down-weighting the distractor dimension or the most likely distractor location. Less clear is how the heterogeneity among the nontarget features, and the similarity of target and distractor modulate distractor interference and thereby distractor location learning. In three tasks, we examined this question by analyzing target reports and selection errors. In the mixed-feature task, participants searched for a singleton shape among homogeneously shaped nontargets, forcing participants to use singleton-detection mode. In two fixed-feature tasks, participants needed feature-search mode to find the target among heterogeneously shaped nontargets, which were either gray (gray fixed-feature task) or coloured (colour fixed-feature task). As expected, the results in the mixed-feature task showed evidence for distractor interference and distractor location learning with suppression of the high-probability location below a baseline level. In the fixed-feature tasks, the results differed: We observed distractor interference in the gray fixed-feature task, but a slight distractor-presence benefit in the colour fixed-feature task, possibly indicating up-weighting of the target on the featural level. Distractor location learning occurred in the first session of the colour fixed-feature task, but results in the gray fixed-feature task indicate that the participants relied on other strategies to handle distraction. Interestingly, we found overnight learning between sessions in all three tasks, which was more pronounced in the fixed-feature tasks. These results indicate that participants can flexibly adjust their attentional strategy based on the nontarget features to reduce distractor interference.

When detecting a salient target makes search more effortful.

Prior research has demonstrated two distinct modes of searching a display: singleton detection mode and feature search mode. Due to the explicit template-based attentional control involved in feature search mode, singleton detection mode is often assumed to be less mentally effortful, which can potentially explain why people search using such an inefficient and distraction-prone strategy. However, this assumption remains largely untested. In the present study, we used a hand dynamometer to relate physical effort to perceived mental effort across different search conditions. Surprisingly, across three experiments, participants exerted more effort to avoid singleton detection trials compared to feature search trials, suggesting that they found singleton detection to be the more effortful mode of searching. In a fourth experiment, we removed the physical effort component and simply asked participants to self-report how effortful they perceived each search task to be. Participants robustly indicated that singleton detection trials were more effortful. Lastly, in a fifth experiment, we removed distractor-present trials. Again, participants exerted more effort to avoid singleton detection trials. In contrast to widely held assumptions, our findings suggest that searching for a salient singleton is in fact more mentally effortful than searching for a specific feature in a heterogeneous display, which has broad implications for theories of attentional control and the influence of mental effort on cognition. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Direct evidence for proactive suppression of salient-but-irrelevant emotional information inputs.

It has long been debated whether emotional information inherently captures attention. The mainstream view suggests that the attentional processing of emotional information is automatic and difficult to be controlled. Here, we provide direct evidence that salient-but-irrelevant emotional information inputs can be proactively suppressed. First, we demonstrated that both negative and positive emotional distractors (fearful and happy faces) induced attentional capture effects (i.e., more attention allocated to emotional distractors than neutral distractors) in the singleton-detection mode (Experiment 1), but attentional suppression effects (i.e., less attention allocated to emotional distractors than neutral distractors) in the feature-search mode that strengthened task motivation (Experiment 2). The suppression effects in the feature-search mode disappeared when emotional information was disrupted through face inversion, showing that the suppression effects were driven by emotional information rather than low-level visual factors (Experiment 3). Furthermore, the suppression effects also disappeared when the identity of emotional faces became unpredictable (Experiment 4), suggesting that the suppression was highly dependent on the predictability of emotional distractors. Importantly, we reproduced the suppression effects using eye-tracking methods and found that there was no attentional capture by emotional distractors before the appearance of the attentional suppression effects (Experiment 5). These findings suggest that irrelevant emotional stimuli that have the potential to cause distraction can be proactively suppressed by the attention system. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Search mode, not the attentional window, determines the magnitude of attentional capture

A salient color distractor is known to capture attention during search for a less salient shape target, but the mechanisms underlying attentional capture are debated. Theeuwes (2004, Psychonomic Bulletin & Review, 11(1), 65–70) argued that attentional capture depends on the size of the attentional window. If the attentional window is large, search is efficient and attentional capture should be stronger because the distractor is more likely to be inside the window. Consistently, we found higher search efficiency and more attentional capture in singleton than in feature search. However, differences in attentional capture only occurred when singleton and feature search were performed by different groups of participants, but not when singleton and feature search occurred unpredictably in the same group of participants. This result contradicts the attentional window account because search efficiency was always higher in singleton than in feature search. Rather, the results support search mode theory, which claims that participants looked for the most salient stimulus in singleton search (“singleton detection mode”), which resulted in more capture by the salient color distractor. When search types varied unpredictably, it was impossible to apply a consistent search strategy, which eliminated the differences between singleton and feature search. Further, we manipulated search efficiency by target–nontarget similarity. With dissimilar nontargets, the target was salient and search efficiency was high. Therefore, the attentional window account predicts more capture. However, we found the opposite result in singleton search and no difference in feature search. Taken together, these observations are inconsistent with the attentional window account but support search mode theory.

Searching for Visual Singletons Without A Feature to Guide Attention.

RT studies have provided evidence for a singleton-detection strategy that is used to search for salient targets when there is no additional featural knowledge that would help guide attention. Despite this behavioral evidence, there have been few ERP studies of singleton detection mode because it was reported early on that the ERP signature of attentional selection (the N2pc) is absent without feature guidance. Recently, however, it was discovered that a small and relatively late N2pc occurs in singleton detection mode along with a previously unreported component called the singleton detection positivity (SDP). Here, we show that both components are influenced by the number of items in the display, as one might expect in a salience-based search mode. Specifically, the N2pc and SDP were larger when the set size was increased to make the singleton "pop out" more easily, when participants responded more quickly regardless of set size, and when RT search slopes were negative (Experiment 1). The latency of the SDP also depended on set size. In Experiment 2, EEG was recorded with a higher density electrode array to better characterize the scalp topography of the components and to estimate their neural sources. Regional sources near the ventral surface of extrastriate cortex in the occipital lobe explained over 96% of N2pc and SDP activities. These results indicate that searching in singleton detection mode selectively modulates processing within perceptual regions of visual cortex.

How Headline Strategies and News Sources Affect Number of User Clicks on WeChat

ABSTRACT This study used 2,623 WeChat article headlines on the Chengdu school food safety event and employed quantitative content analysis to explore the dynamic relationship of headline strategy (i.e., headline style and headline frame) and news source with user clicks at distinct phases of the issue–attention cycle. The results first revealed that various types of headline styles affect the number of user clicks based on the issue–attention phase, but no single type dominates public attention at any phase. Second, reader attention could be attracted using the information with the singleton detection mode. However, the feature search mode could filter official-oriented discourse. Third, the “treatment recommendation” headline frame, which clearly summarises the core of texts, generally lacked executability and had a poor effect on audience mobilisation. Fourth, readers depended on certain media channels under low-choice media environment, and information issued by administrative sources was not widely spread because of the limitation on their functions and specific targets. Finally, news from traditional mainstream media, online communities, and independent sources were more click-attractive news than the news from other sources, thus demonstrating a complementary relationship between official reports and social media discourses.

Automatic capture of attention by flicker

Visual motion captures attention, but little is known about the automaticity of these effects. Here, we tested if deviant flicker frequencies, as one form of motion, automatically capture attention. Observers searched for a vertical target among tilted distractors. Prior to the target display, a cue array of sinusoidally modulating (flickering) annuli, each surrounding one location of the subsequent target(-plus-distractors) display was presented for variable durations. Annuli either flickered all at 1 Hz (neutral condition, no-singleton cue), or a single annulus flickered at a unique frequency of 5 Hz, 10 Hz, or 15 Hz. The location of this singleton-frequency cue was uncorrelated with target location. Thus, we could measure benefits (target at cued location) and costs (target ≠ cued location) for cues of different frequencies and durations. The results showed that deviant flicker frequencies capture attention, as we observed benefits and costs, falsifying that nonspatial filtering accounted for the cueing effect. In line with automatic capture, cueing was effective in singleton (Experiment 1) and nonsingleton search tasks (Experiment 2), and is thus not dependent on (“top-down”) singleton detection mode. Moreover, analysis of results ruled out trial-by-trial “swapping” of flicker frequencies from preceding target to subsequent distractor locations. Results also revealed increasing cueing effects with higher cue flicker frequency and longer duration. This indicates a significantly longer period of automatic capture by sinusoidal flicker than the typical inhibition of return observed around 250 ms after the onset of uninformative static or single-transient cues.

Attentional dwelling and capture by color singletons.

Can salient stimuli-such as color singletons and abrupt onsets-involuntarily capture spatial attention? We previously reported evidence that abrupt onsets can capture attention, but the effects of this capture can become latent under easy visual search. The present experiments examined whether a similar pattern of latent capture occurs for task-irrelevant color singletons. Participants searched for a perfect circle among oval distractors. We manipulated search difficulty by varying the width of the oval distractors, making them more or less target-like (i.e., more or less circular). With search displays of homogeneous distractors, cue validity effects increased linearly with search difficulty, indicating capture by color singletons (Experiments 1 and 2). With heterogeneous distractors, however, discouraging the use of singleton-detection mode to find the target circle, cue validity effects from color singletons were negligible at all difficulty levels (Experiment 3). Using these exact same heterogeneous search displays, meanwhile, abrupt onsets produced very large cue validity effects (Experiment 4). We conclude that whereas abrupt onsets can capture attention based purely on salience, static color singletons capture attention only when made task-relevant by promoting singleton-detection mode (i.e., contingent capture). The data further support an attentional dwelling account of capture costs and reinforce the recommendation that, to ensure sensitivity to detect the presence (or absence) of attention capture, capture experiments should employ a difficult visual search.

Electrophysiological correlates of visual singleton detection.

Identifying a fixed-feature singleton that pops out from an otherwise uniform array of distractors elicits an ERP component called the N2pc over the posterior scalp. The N2pc has been used to track attention with millisecond accuracy, inform theories of visual selection, and test for specific attention deficits in clinical populations, yet it is still unclear what neuro-cognitive process gives rise to the component. One hypothesis is that the N2pc reflects a spatial filtering process that suppresses irrelevant distractors. In support of this hypothesis, Luck and Hillyard (1994a) showed that the N2pc is eliminated when the features of the target and distractors switch unpredictably across trials (so that participants cannot prepare to filter out irrelevant items). The present study aimed to replicate Luck and Hillyard's singleton detection experiment but with modifications to enhance the N2pc signal and to gain statistical power. We show that orientation singletons do, in fact, elicit the N2pc as well as an earlier-onset and longer-lasting singleton detection positivity over the occipital scalp when the target and distractor orientations swap randomly across trials. We conclude that spatial filtering might not play a major role in the generation of the N2pc and that the selection processes required to search for fixed-feature targets (in feature-search mode) are also engaged in the detection of variable-feature singletons (in singleton detection mode).

Learning to ignore salient distractors: Attentional set and habituation

ABSTRACTAttentional capture by salient distractors can be attenuated by the target search strategy (feature-search mode vs. singleton-detection mode) adopted, as well as by learning processes concerning the distractor features. Hence, two different models, one based on the task-relevant and one on the task-irrelevant information, would interact in the control of attention. Here, we investigated whether the search mode used to locate the target can affect the possibility to reject salient distractor on the basis of habituation mechanisms. Our results showed that when a feature-search mode was used, capture by a uniquely-coloured distractor was progressively reduced with practice, a result consistent with the habituation of capture phenomenon (Experiment 1). Conversely, when a singleton-detection mode was used habituation of capture was prevented (Experiment 2), both when the distractor feature remained constant (Experiment 3) and when a prolonged exposure to the distractor was allowed (Experiment 4). We propose that when the templates for the task-relevant (i.e., the target) and the task-irrelevant (i.e., the distractor) information overlap the former prevails in the control of attention, and prevents habituation of capture to take place.

Taking a closer look at visual search: Just how feature-agnostic is singleton detection mode?

Singleton detection mode is a state in which spatial attention is set to prioritize any objects that differ from all other objects present on any feature dimension. Relatively little research has been devoted to confirming the consequences such a search mode has for stimulus processing. It is often implied that when observers employ singleton detection mode, all singletons capture attention equally, and when observers search for a single feature, only that feature captures attention. The experiment presented here contradicts these implications. We had observers search for colored singleton targets preceded by spatially uninformative colored singleton cues, and we recorded stimulus-evoked neural responses using electroencephalography (EEG). When observers had to respond to targets defined by two possible colors (a task intended to encourage singleton detection mode), cue validity effects were apparent for both target-color cues and irrelevant-color cues, and these effects were accompanied by an N2pc in the EEG data. Importantly, however, the target-color cues evoked significantly larger cue validity effects and N2pc components than did the irrelevant-color cues. In contrast, when observers had to respond to targets defined by one color (a task intended to encourage feature search mode), only cues of that color evoked a cue validity effect. Interestingly, the N2pcs produced by irrelevant cues did not differ between feature and singleton search, suggesting that the behavioral difference was not due to different attentional orienting. Rather, we suggest that behavioral singleton capture is due to a diminished same-location cost being produced by irrelevant-color cues.

Transition from feature-search to singleton-detection strategies in visual search: The role of number of target-defining options.

When searching for a uniquely colored target in an RSVP stream of homogeneously colored nontarget items, observers can use singleton-detection and/or feature-search modes. Using an attentional-capture paradigm, we varied systematically (a) the number of possible target colors from 1 to 4 and (b) the presence or absence of a colored ring surrounding the nontarget item displayed 200 ms before the target. When present, the ring was either the same color as 1 of the possible targets (color-match), or an irrelevant color (color-mismatch). Capture was measured as the impairment in target identification accuracy when the ring was present relative to when it was absent. Greater capture in the color-match than in the color-mismatch condition was regarded as evidence of feature-search mode. Capture in the color-mismatch condition was regarded as evidence for singleton-detection mode. We show that, as the number of target colors is increased, the relative prominence of feature-search mode decreases, and that of singleton-detection mode increases correspondingly. This novel finding shows that, when both feature-search and singleton-detection modes are possible, at least some degree of feature-search mode is used until the number of possible target-defining colors reaches about 4. This suggests that the weight assigned to singleton-detection mode increases, and that assigned to feature-search mode decreases correspondingly, as the difficulty of maintaining the target-defining features in mind is increased. (PsycINFO Database Record

Attentional Dwelling and Capture by Color Singletons

Can salient stimuli—such as color singletons and abrupt onsets—involuntarily capture spatial attention? We previously reported evidence that abrupt onsets can capture attention, but the effects of this capture can become latent under easy visual search. The present experiments examined whether a similar pattern of latent capture occurs for task-irrelevant color singletons. Participants searched for a perfect circle among oval distractors. We manipulated search difficulty by varying the width of the oval distractors, making them more or less target-like (i.e., more or less circular). With search displays of homogeneous distractors, cue validity effects increased linearly with search difficulty, indicating capture by color singletons (Experiments 1 and 2). With heterogeneous distractors, however, discouraging the use of singleton-detection mode to find the target circle, cue validity effects from color singletons were negligible at all difficulty levels (Experiment 3). Using these exact same heterogeneous search displays, meanwhile, abrupt onsets produced very large cue validity effects (Experiment 4). We conclude that whereas abrupt onsets can capture attention based purely on salience, static color singletons capture attention only when made task-relevant by promoting singleton-detection mode (i.e., contingent capture). The data further support an attentional dwelling account of capture costs and reinforce the recommendation that, to ensure sensitivity to detect the presence (or absence) of attention capture, capture experiments should employ a difficult visual search.

Active suppression of salient-but-irrelevant stimuli does not underlie resistance to visual interference

In visual search for a shape target, interference from salient-but-irrelevant color singletons can be resisted in feature search mode, but not in singleton detection mode. In singleton detection mode, we observed a contralateral positivity (PD) after 260–340ms, suggesting that the salient distractor was suppressed. Because RTs in singleton detection mode increased when a distractor was present, we conclude that active suppression of distractors takes time. In feature search mode, no increase in RTs and no PD to the distractor was observed, showing that resistance to interference was not accomplished by suppression. Rather, the smaller N2pc to the target in feature search than in singleton detection mode suggests that enhancement of target features avoided interference. Thus, the strong top-down set in feature search mode eliminated the need to suppress the early attend-to-me signal (corresponding to the Ppc, from 160 to 210ms) that was generated by salient stimuli independently of search mode.

Attentional capture during attentional awakening.

We investigated whether attentional set is available at the beginning of a trial or whether it develops gradually within a trial. Thus, we manipulated the time from the onset of a trial to a target and observers' search strategy. We also observed the effect of the presence or absence of distractors as an index of the temporal development of attentional set. Participants identified a target letter embedded in a stream of rapidly presented nontargets while ignoring peripheral distractors. Baseline accuracy when no peripheral distractor was presented increased as the target appeared later in the stream, suggesting attentional awakening. Identification accuracy was impaired by the presence of peripheral distractors (i.e., attentional capture) early in the stream only when observers adopted the feature search mode. The magnitude of attentional capture increased over the course of the first 1,000 ms of a trial under the singleton detection and feature search modes. These results suggest that singleton detection mode requires time for a bottom-up signal to be effective in capturing attention, whereas the feature search mode does not require such a warm-up period to be effective and is available from the beginning of viewing the stream.

Behavioral Evidence of Top-Down Suppression of Attention Capture with the Letter-Probe Technique

There is considerable debate about how visual attention is involuntarily drawn to salient stimuli (called attention capture). Stimulus-driven theories posit that certain super salient stimulus features automatically capture attention, whereas goal-driven theories posit that only stimuli matching our attentional set (i.e., what we are looking for) capture attention. In the current study, we test a hybrid account (called the signal suppression theory), which posits that salient stimuli produce an automatic “attend-to-me” signal but that this signal may be suppressed if the observer exerts strong top-down control. To test this hypothesis, we used a modified additional singleton paradigm in which participants searched for a target shape and attempted to ignore an irrelevant color singleton. We manipulated search mode (singleton-detection mode vs. feature search mode) to encourage or discourage attention capture. On a small subset of trials, participants were instead asked to perform a probe task. On these trials, letters appeared briefly at each search location and participants reported all letters they saw. When singleton detection mode was encouraged, attention capture was observed on the no-probe trials. On probe trials, participants were more likely to report the singleton probe letter than distractor or target probes. When feature search mode was encouraged, capture was not observed on the no-probe trials. On probe trials, participants were less likely to report the singleton probe letter than the target or distractor probes. This behavioral evidence corroborates previous ERP-based evidence of top-down suppression of singleton distractors when participants are in feature search mode. In addition, the finding that singleton detection mode led to improved probe processing at the singleton location provides strong evidence against the hypothesis that attention capture effects in the additional singleton paradigm reflect “filtering costs” (a generalized slowing of responses) rather than true capture of attention to the singleton’s location. Meeting abstract presented at VSS 2015

Rewards shape attentional search modes

Visual attention can be configured for specific stimulus features (feature search mode) or it can be non-specifically set for salient pop-outs (singleton detection mode). Additionally, monetary rewards have been shown to bias attention toward specific features, but it is unknown whether secondary reinforcers (images of US$) can shape global attention via search modes. In a between-group study, we trained participants to value one search mode over the other. In a testing phase, a salient distractor captured the attention of the value-singleton group; however, the value feature group was completely unaffected. This suggests that rewards automatically bias global attention mechanisms and potentially mediate the handoff between stimulus-driven and goal-directed attentional control.

Capture by colour: evidence for dimension-specific singleton capture.

Previous work on attentional capture has shown the attentional system to be quite flexible in the stimulus properties it can be set to respond to. Several different attentional "modes" have been identified. Feature search mode allows attention to be set for specific features of a target (e.g., red). Singleton detection mode sets attention to respond to any discrepant item ("singleton") in the display. Relational search sets attention for the relative properties of the target in relation to the distractors (e.g., redder, larger). Recently, a new attentional mode was proposed that sets attention to respond to any singleton within a particular feature dimension (e.g., colour; Folk & Anderson, 2010). We tested this proposal against the predictions of previously established attentional modes. In a spatial cueing paradigm, participants searched for a colour target that was randomly either red or green. The nature of the attentional control setting was probed by presenting an irrelevant singleton cue prior to the target display and assessing whether it attracted attention. In all experiments, the cues were red, green, blue, or a white stimulus rapidly rotated (motion cue). The results of three experiments support the existence of a "colour singleton set," finding that all colour cues captured attention strongly, while motion cues captured attention only weakly or not at all. Notably, we also found that capture by motion cues in search for colour targets was moderated by their frequency; rare motion cues captured attention (weakly), while frequent motion cues did not.

The effect of search mode on dimension weighting.

In a visual feature search task, reaction times to a singleton target are known to be shorter when participants have advance knowledge of the defining-features of targets. The present study examined whether the prior-knowledge effect is influenced by search modes (feature vs. singleton). In addition, using a variant of the flanker task, the present study assessed whether prior-knowledge affected efficiency of attentional focusing to a target. When participants performed a target discrimination task (i.e., compound search task), using a singleton detection mode, no prior-knowledge effect was found (Experiments 1 and 3). However, when the same task was performed using a feature search mode, prior-knowledge facilitated performance (Experiment 2). This suggests that the dimension weighting of a target-defining feature is modulated by the search mode. Also flanker response congruency was affected by prior-knowledge suggesting that the dimension weighting correlated with attentional focusing to targets. On the other hand, inter-trial dimensional priming was not affected by the search mode. Implications for mechanisms of feature-based top-down control of attention in visual feature search are discussed.