Attention In Visual Search Research Articles

Attentional guidance from unique faster/slower discrete and smooth feature changes in visual search

ABSTRACT Two studies examine the circumstances in which singletons, defined by unique feature-change rate, guide attention in visual search. Participants searched for a static vertical/horizontal white target bar amidst tilted distractors. Bars were contained inside surround shapes with periodically oscillating features. In Experiment 1, displays consisted of surrounds with abrupt (discrete) or continuous (smooth) changes between two values (red–blue, square–diamond). For discrete displays, target surrounds did not guide attention when uniquely faster-oscillating than distractor surrounds, but did in smooth displays. For unique-slow oscillating target surrounds, the opposite guidance pattern was found across discrete and smooth displays. In Experiment 2, displays had a mixture of discrete and smooth surrounds. Here, only unique slow-oscillating discrete surrounds guided attention. No guidance was found for smooth surrounds. Findings suggest that faster oscillations are masked by higher-frequency harmonic signals from slower changing discrete items, and there is attentional prioritization of discrete over smooth changes.

Eye movements reveal the contributions of early and late processes of enhancement and suppression to the guidance of visual search

In visual search attention can be directed towards items matching top-down goals, but this must compete with factors such as salience that can capture attention. However, under some circumstances it appears that attention can avoid known distractor features. Chang and Egeth (Psychological Science, 30 (12), 1724–1732, 2019) found that such inhibitory effects reflect a combination of distractor-feature suppression and target-feature enhancement. In the present study (N = 48), we extend these findings by revealing that suppression and enhancement effects guide overt attention. On search trials (75% of trials) participants searched for a diamond shape among several other shapes. On half of the search trials all objects were the same colour (e.g., green) and on the other half of the search trials one of the non-target shapes appeared in a different colour (e.g., red). On interleaved probe trials (25% of trials), subjects were presented with four ovals. One of the ovals was in either the colour of the target or the colour of the distractor from the search trials. The other three ovals were on neutral colours. Critically, we found that attention was overtly captured by target colours and avoided distractor colours when they were viewed in a background of neutral colours. In addition, we provided a time course of attentional control. Within visual search tasks we observed inhibition aiding early attentional effects, indexed by the time it took gaze to first reach the target, as well as later decision-making processes indexed by the time for a decision to be made once the target as found.

Facial hair may slow detection of happy facial expressions in the face in the crowd paradigm

Human visual systems have evolved to extract ecologically relevant information from complex scenery. In some cases, the face in the crowd visual search task demonstrates an anger superiority effect, where anger is allocated preferential attention. Across three studies (N = 419), we tested whether facial hair guides attention in visual search and influences the speed of detecting angry and happy facial expressions in large arrays of faces. In Study 1, participants were faster to search through clean-shaven crowds and detect bearded targets than to search through bearded crowds and detect clean-shaven targets. In Study 2, targets were angry and happy faces presented in neutral backgrounds. Facial hair of the target faces was also manipulated. An anger superiority effect emerged that was augmented by the presence of facial hair, which was due to the slower detection of happiness on bearded faces. In Study 3, targets were happy and angry faces presented in either bearded or clean-shaven backgrounds. Facial hair of the background faces was also systematically manipulated. A significant anger superiority effect was revealed, although this was not moderated by the target’s facial hair. Rather, the anger superiority effect was larger in clean-shaven than bearded face backgrounds. Together, results suggest that facial hair does influence detection of emotional expressions in visual search, however, rather than facilitating an anger superiority effect as a potential threat detection system, facial hair may reduce detection of happy faces within the face in the crowd paradigm.

Visual attention in spatial cueing and visual search.

To characterize internal processes of an observer conducting perceptual tasks, we developed an observer model that combines the perceptual template model (PTM), the attention mechanisms in the PTM framework (Lu & Dosher, 1998), and uncertainty of signal detection theory (Green & Swets, 1966). The model was evaluated with a visual search experiment conducted in a range of external noise, signal contrast, and target-distractor similarity conditions. In each trial, eight Gabor patches were shown in each of two brief intervals, with one target at a different orientation from the distractors in one of the presentations. Subjects were precued to a subset of the stimuli (1, 2, 4, or 8) and asked to report (a) which interval contained the target and (b) where the target was. Individual roles of uncertainty and of attention in visual search were investigated by comparing models with and without an attention component. The results showed that decision uncertainty alone was sufficient to account for the set-size effect, even in conditions with high target-distractor similarity. Our theoretical model and empirical results provide a coherent picture regarding how visual information is selected and processed during feature search.

The efficiency of visual search for a frequently changed target is preserved in older adults.

Visual search is a psychological function integral to most people's daily lives. The extent to which visual search efficiency, and in particular the ability to use top-down attention in visual search, changes across the lifespan has been the focus of ongoing research. Here we sought to understand how the ability to frequently and dynamically change the target in a conjunction search task was affected by ageing. To do this, we compared visual search performance of a group of younger and older adults under conditions in which the target type was determined by a cue and could change on trial-to-trial basis (Intermixed), versus when the target type was fixed for a block of trials (Blocked). Although older adults were overall slower at the conjunction visual search task, and both groups were slower in the Intermixed compared with the Blocked Condition, older adults were not disproportionately affected by the Intermixed relative to the Blocked conditions. These results indicate that the ability to frequently change the target of visual search is preserved in older adults. This conclusion is consistent with an emerging consensus that many aspects of visual search and top-down contributions to it are preserved across the lifespan. It is also consistent with a growing body of work which challenges the neurocognitive theories of ageing that predict sweeping deficits in complex top-down components of cognition.

Typicality modulates attentional capture by object categories

What we pay attention to in the visual environment is often driven by what we know about the world. For example, a number of studies have found that observers can adopt attentional sets for a particular semantic category. However, some objects are more typical members of a category than others. While previous evidence suggests that an object's typicality can influence the guidance of attention in visual search, it is unclear whether typicality can also influence the capture of attention. To test whether this is the case, participants were given a category of objects at the beginning of each trial. Then, a rapid serial visual presentation (RSVP) stream was presented at fixation, and participants had to indicate whether an object of the given category was present or absent from the stream. Importantly, a single flanker image also appeared above or below the central stream just before the target. This flanker could belong either to the same category as the target or a different category, and could be a typical or atypical exemplar of that category. Participants were less accurate at detecting the target when the flanker belonged to the same category as the target. Moreover, participants were even less accurate when the flanker was a typical exemplar of this category. Similar findings were observed when targets consisted of typical and atypical exemplars. Together, these findings indicate that the extent of attentional capture toward a distractor depends on whether the distractor matches the category and typicality of one's attentional set.

Effects of Acute Visual Stimulation Exercise on Attention Processes: An ERP Study.

Backgrounds: It remains to be determined whether visual stimuli during exercise differentially influence the attention process. The purpose of the present study was to examine if different color stimuli during aerobic exercise are associated with different attention processes. Methods: 22 college students completed a four 30-min running session during the presentation of different color stimuli (blue, green, red, and yellow) and without color stimulus on separate visits. The Kanizsa triangle task was administrated before and immediately after exercise to assess the attention process. Behavioral performance (accuracy and response time (RT)) and event-related potential (P2, N2b and P3a) were recorded during the test. Results: Valid/invalid cue RT during the Kaniza test performance was significantly faster following the presentation of color stimuli during treadmill exercise compared to the seated rest. During exercise, these changes were larger after green and yellow stimuli than red in invalid cue RT. P2, N2b and P3a amplitudes of green were significantly larger than the other colors for both valid and invalid cues. Red color showed the lowest P2 and P3a amplitudes for both valid and invalid cues among colors. Conclusion: The distinctive neurocognitive changes during aerobic exercise suggest different effects of color stimuli on visual search attention, attention capture, attentional orienting and processing speed. This study will be a first step to understand the optimal environmental setting during exercise for subsequent improvements in the attention process.

ROC and SAT Analysis of Different Grayscale Test Images (Distractors L and Target T) to Customize a Visual-Search Attention Task

Nowadays, there is a great need to investigate the effects of fatigue on physical as well as mental performance. The issues that are generally associated with extreme fatigue are that one can easily lose one’s focus while performing any particular activity whether it is physical or mental and this decreases one’s motivation to complete the task at hand efficiently and successfully. In the same line of thought, myriads of research studies posited the negative effects of fatigue on mental performance, and most techniques to induce fatigue to require normally long-time and repetitive visual search tasks. In this study, a visual search algorithm task was devised and customized using performance measures such as d’ (d-prime) and Speed Accuracy Trade-Off (SATF) as well as ROC analysis for classifier performance. The visual search algorithm consisted of distractors (L) and a target (T) whereby human participants had to press the appropriate keyboard button as fast as possible if they notice a target or not upon presentation of a visual stimulus. It was administered to human participants under laboratory conditions, and the reaction times, as well as accuracy of the participants, were monitored. It was found that the test image Size35Int255 was the best image to be used in terms of sensitivity and AUC (Area under Curve). Therefore, ongoing researches can use these findings to create their visual stimuli in such a way that the target and distractor images follow the size and intensity characteristics as found in this research.

Typicality Modulates Attentional Capture by Object Categories

What we pay attention to in the visual environment is often driven by what we know about the world. For example, a number of studies have found that observers can adopt attentional sets for a particular semantic category. However, some objects are more typical members of a category than others. While previous evidence suggests that an object’s typicality can influence the guidance of attention in visual search, it is unclear whether typicality can also influence the capture of attention. To test whether this is the case, participants were given a category of objects at the beginning of each trial. Then, a rapid serial visual presentation (RSVP) stream was presented at fixation, and participants had to indicate whether an object of the given category was present or absent from the stream. Importantly, a single flanker image also appeared above or below the central stream just before the target. This flanker could belong either to the same category as the target or a different category, and could be a typical or atypical exemplar of that category. Participants were less accurate at detecting the target when the flanker belonged to the same category as the target. Moreover, participants were even less accurate when the flanker was a typical exemplar of this category. Similar findings were observed when targets consisted of typical and atypical exemplars. Together, these findings indicate that the extent of attentional capture toward a distractor depends on whether the distractor matches the category and typicality of one’s attentional set.

No Advantage for Separating Overt and Covert Attention in Visual Search.

We move our eyes roughly three times every second while searching complex scenes, but covert attention helps to guide where we allocate those overt fixations. Covert attention may be allocated reflexively or voluntarily, and speeds the rate of information processing at the attended location. Reducing access to covert attention hinders performance, but it is not known to what degree the locus of covert attention is tied to the current gaze position. We compared visual search performance in a traditional gaze-contingent display, with a second task where a similarly sized contingent window is controlled with a mouse, allowing a covert aperture to be controlled independently by overt gaze. Larger apertures improved performance for both the mouse- and gaze-contingent trials, suggesting that covert attention was beneficial regardless of control type. We also found evidence that participants used the mouse-controlled aperture somewhat independently of gaze position, suggesting that participants attempted to untether their covert and overt attention when possible. This untethering manipulation, however, resulted in an overall cost to search performance, a result at odds with previous results in a change blindness paradigm. Untethering covert and overt attention may therefore have costs or benefits depending on the task demands in each case.

The architecture of working memory: Features from multiple remembered objects produce parallel, coactive guidance of attention in visual search.

Theories of working memory (WM) differ in their claims about the number of items that can be maintained in a state that directly interacts with other, ongoing cognitive operations (termed the focus of attention). A similar debate has arisen in the literature on visual working memory (VWM), focused on the number of items that can simultaneously interact with attentional priority. In 3 experiments, we used a redundancy-gain paradigm to provide a comprehensive test of the latter question. Participants searched for 2 cued features (e.g., a color and a shape) within a search array. The cued feature values changed on a trial-by-trial basis, requiring VWM. The target (when present) could match 1 of the cued features (single-target trials) or both cued features (redundant-target trials). We tested whether response time distributions contained a substantial proportion of trials with redundant-target responses that were faster than predicted by 2 independent guidance processes operating in parallel (i.e., violations of the race-model inequality). Violations are consistent with a coactive architecture in which both cued values guide attention in parallel and sum on the priority map. Robust violations were observed in all cases predicted by the hypothesis that multiple items in VWM can guide attention simultaneously, and these results were inconsistent with the hypothesis that guidance is limited to a single item simultaneously. When considered in the larger context of the literature on VWM and attention, the present results are consistent with a model of WM architecture in which the focus of attention can maintain multiple, independent representations. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Effects of Physical Exercise on Working Memory and Attention-Related Neural Oscillations.

Cognitive functions, such as working memory (WM) and attention, have been shown to benefit from physical exercise. Quantifying frequency-band-specific neural oscillatory patterns during the use of such cognitive functions can provide insight into exercise-induced benefits in the brain. Specifically, we investigated whether a 4-month physical exercise training influenced theta and alpha power measured in visual WM and attention tasks. The delayed match-to-sample (DMS) task required mnemonic discrimination of similar visual stimuli, akin to pattern separation, while the visual-attention search (VAS) task required detecting the presence of a specific object (i.e., target) in an image. Behavioral and electroencephalographic data were acquired during a DMS visual WM task and VAS task both before and after the intervention. Forty-three sedentary young adults (19–34 years) were pseudorandomly assigned to a training group (indoor treadmill, n = 20) or to a control group (n = 23). Compared to the preintervention baseline, the exercise group showed increased frontal alpha power (9–12 Hz) during the VAS task after the intervention. In addition, alpha power changes correlated positively with fitness changes. Behaviorally, there were no exercise-related effects on reaction times or accuracy in either task. Our findings substantiate that aerobic training of sedentary young adults may influence neural dynamics underlying visual attention rather than visual WM and mnemonic discrimination.

Is apparent instability a guiding feature in visual search?

ABSTRACT Humans are quick to notice if an object is unstable. Does that assessment require attention or can instability serve as a preattentive feature that can guide the deployment of attention? This paper describes a series of visual search experiments, designed to address this question. Experiment 1 shows that less stable images among more stable images are found more efficiently than more stable among less stable; a search asymmetry that supports guidance by instability. Experiment 2 shows efficient search but no search asymmetry when the orientation of the objects is removed as a confound. Experiment 3 independently varies the orientation cues and perceived stability and finds a clear main effect of apparent stability. Experiment 4 shows converging evidence for a role of stability using different stimuli that lack an orientation cue. However, here both search for stable and unstable targets is inefficient. Experiment 5 is a control for Experiment 4, showing that the stability effect in Experiment 4 is not simple side-effects of the geometry of the stimuli. On balance, the data support a role for instability in the guidance of attention in visual search. (184 words)

Exogenous Orientation of Attention to the Center of Mass in a Visual Search Task

Anne Treisman's scientific career included broad-ranging contributions that advanced our understanding of the attentional mechanisms that people rely on to make sense of the world. In this paper, we describe results from a visual-search paradigm first developed by Grabowecky and Treisman (Grabowecky, 1992). Their design exploited known feature-search asymmetries (Treisman & Gormican, 1988) to investigate the role of a centerofmass (CoM) mechanism in determining the initial locus of visual-spatial attention in visual search. The original experiment supported the hypothesis that CoM influences initial orienting of visual-spatial attention, as targets near the CoM of a multi-element array were detected more quickly than targets distant from the CoM. These findings were replicated in a follow-up experiment using a different feature-search asymmetry, with eye-tracking added to verify central fixation. We also investigated whether CoM had any influence on pop-out search, and found no evidence that it does. Surprisingly, the effect of position of the search array on the CoM suggested that CoM may be computed independently for elements contained within each visual hemifield. Whereas our work on CoM with Treisman was initiated within an earlier theoretical context, the present results are also compatible with contemporary theoretical advances; both the early results and the new results can be integrated within current ways of thinking about attention and pre-attentive mechanisms.

Supplemental Material for The Architecture of Working Memory: Features From Multiple Remembered Objects Produce Parallel, Coactive Guidance of Attention in Visual Search

Supplemental Material for The Architecture of Working Memory: Features From Multiple Remembered Objects Produce Parallel, Coactive Guidance of Attention in Visual Search

Opposing effects of stimulus-driven and memory-driven attention in visual search

A recent study (Jung, Han, & Min, in press) reported that the extent to which attentional control is strained is a critical factor for observing stimulus-driven attentional capture in visual search. Expanding this study, we tested whether memory-driven attentional capture is also dependent on cognitive mechanism underlying visual search tasks. In our experiment, a group of participants performed a dual task, consisting of a working memory and a visual search task (memory-driven attention group), whereas the other performed only a visual search task (stimulus-driven attention group). Each group was further divided into two groups depending on the search task performed. For visual search tasks, we utilized two different search tasks; Landolt-C and orientation feature search tasks. For the former, participants searched for an outlined square with a top- or bottom-gap among left- or right-gap squares. For the latter, participants looked for a right- or left-tilted line among vertical lines. In a half of the total trials, a memory-matching/salient singleton distractor was present. In the remaining trials, no such a memory-matching/singleton distractor was present. As results, attentional capture by the singleton distractor was found under feature search task, p< .01. On the contrary, the task-irrelevant distractor did not capture when participants performed the Landolt-C search, p> .45. The memory-driven group showed a different pattern. A task-irrelevant, memory matching distractor captured attention when participants performed Landolt-C search task, p< .001. However, no memory-driven attentional capture was found under the feature search, p > .72. Our results demonstrate that the nature underlying visual search tasks is an important factor for observing both stimulus-driven and memory-driven attention. However, the specific patterns of the capture were opposite. These findings point to the role of interplay between the extent to which attentional control is strained and working memory in attentional capture.

The roles of relevance and expectation for the control of attention in visual search.

Representations of target-defining features (attentional templates) control the allocation of attention during visual search. We investigated whether template-guided attentional selectivity is sensitive not only to the relevance of visual features, but also to expectations about their probability. Search displays could contain a target in an expected (80%) or unexpected (20%) color. They were preceded by spatially uninformative cues that matched either the expected or unexpected target color. These color cues attracted attention, reflected by behavioral spatial cueing effects and by cue-elicited N2pc components obtained via EEG measured during task performance. Critically, these attentional capture effects were identical for both color cues, suggesting that preparatory attentional templates only reflect relevance, and are insensitive to expectations about target color probabilities. In contrast, RTs and N2pc components to search targets in the unexpected color were delayed, showing that expectations modulated the speed of attentional target selection within search displays. This dissociation between the effects of relevance and expectation on attentional preparation versus target selection suggests that these 2 parameters for attentional control are represented differently. Task relevance is likely to be specified at the level of individual features, whereas expectations could be represented in an object-based fashion. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

How robust and rapid can the memory-driven attentional capture be?

Previous research has indicated that visual attention can be automatically captured by sensory inputs that match the contents of visual working memory. Furthermore, the information in visual working memory can be used as a template of memory guidance for either the selection or rejection of visual attention. The current study investigated the memory-driven attentional processes in four experiments which extend and complement previous research. Participants performed a visual search task while maintaining items in visual working memory. Experiment 1 used an arrow as a pre-cue indicating which side of the screen the search target would appear on. Experiment 2 used two circles as pre-cues for the right-up/down location of the search target. Experiment 3 presented a memory-matching distractor for 300 ms followed by a blank screen. Experiment 4 presented a memory-matching distractor for 150 ms followed by the visual search task. All experiments resulted in significantly slower visual search reaction times (RTs) for the invalid condition (memory-matching distractor) compared to the neutral condition but with no significant differences in memory performance. This result suggests that the contents of working memory affect the deployment of attention in visual search. Our findings show that attentional capture occurs even within short periods of 150 ms, which demonstrates the robustness and speed of memory-driven attentional processes. Consequently, attentional capture appears to be initiated at an early phase of visual processing but can be strategically inhibited through cognitive control at later stages of analysis.

Capture and Control: Working Memory Modulates Attentional Capture by Reward-Related Stimuli

Physically salient but task-irrelevant distractors can capture attention in visual search, but resource-dependent, executive-control processes can help reduce this distraction. However, it is not only physically salient stimuli that grab our attention: Recent research has shown that reward history also influences the likelihood that stimuli will capture attention. Here, we investigated whether resource-dependent control processes modulate the effect of reward on attentional capture, much as for the effect of physical salience. To this end, we used eye tracking with a rewarded visual search task and compared performance under conditions of high and low working memory load. In two experiments, we demonstrated that oculomotor capture by high-reward distractor stimuli is enhanced under high memory load. These results highlight the role of executive-control processes in modulating distraction by reward-related stimuli. Our findings have implications for understanding the neurocognitive processes involved in real-life conditions in which reward-related stimuli may influence behavior, such as addiction.

Opposing effects of stimulus-driven and memory-driven attention in visual search.

When one searches for a specific target in a cluttered visual scene, a perceptually salient stimulus or a stimulus that matches working memory's contents is prioritized for attentional selection. In the present study, we aimed at clarifying under which circumstance stimulus-driven attention or memory-driven attention is more pronounced. We hypothesized that one crucial factor affecting stimulus-driven versus memory-driven attention is how a concurrent visual search task is performed. To address this issue, we employed two visual search tasks whose underlying mechanisms are known to be different: Landolt-C search and orientation feature search. One group of participants performed visual search tasks containing a memory-matching stimulus, and the other group conducted searches in the presence of a salient singleton distractor. The results showed that the effects of stimulus-driven and memory-driven attention differed, depending on the cognitive mechanisms underlying the visual search tasks. A memory-matching stimulus captured attention when participants performed the Landolt-C search, whereas this capture was diminished under feature search. In contrast, capture by the salient singleton distractor was found only under feature search. These results demonstrate that the nature of the underlying visual search tasks is an important factor for observing stimulus-driven versus memory-driven attention. Our results also provide a potential solution to resolve current debate regarding memory-driven attention in visual search.