Distractor Color Research Articles

Effects of target and distractor saturations on the cognitive performance of an integrated display interface

Color coding is often used to enhance decision quality in complex man-machine interfaces of integrated display systems. However, people are easily distracted by irrelevant colors and by the numerous data points and complex structures in the interface. Although an increasing number of studies are seriously focusing on the problem of achieving efficient color coding, few are able to determine the effects of target and distractor saturations on cognitive performance. To study the performances of target colors among distractors, a systematic experiment is conducted to assess the influence of high and low saturated targets on cognitive performance, and the affecting extent of different saturated distractors of homogeneous colors on targets. According to the analysis of the reaction time through the non-parametric statistical method, a calculation method of the cognitive performance of each color is proposed. Based on the calculation of the color differences and the accumulation of the reaction times, it is shown that with the different saturated distractors of homogeneous colors, the high saturated yellow targets perform better than the low saturated ones, and the green and blue targets have moderate performances. When searching for a singleton target placed on a black background, the color difference between the target and the distractor should be more than 20ΔE*ab units in the yellow saturation coding, whereas the color difference should be more than 40ΔE*ab units in the blue and green saturation coding. In addition, as regards saturation coding, the influence of the color difference between the target and the background on cognitive performance is greater than that of the color difference between the target and the distractor. Seemingly, the hue attribute determines whether the saturation difference between the target and the distractor affects the cognitive performance. Based on the experimental results, the simulation design of the instrument dials in a flight situation awareness interface is completed and tested. Simulation results show the feasibility of the method of choosing the target and distractor colors, and the proposed research provides the instruction for the color saturation design of the interface.

Hyperfocusing in schizophrenia: Evidence from interactions between working memory and eye movements.

Recent research suggests that processing resources are focused more narrowly but more intensely in people with schizophrenia (PSZ) than in healthy control subjects (HCS), possibly reflecting local cortical circuit abnormalities. This hyperfocusing hypothesis leads to the counterintuitive prediction that, although PSZ cannot store as much information in working memory as HCS, the working memory representations that are present in PSZ may be more intense than those in HCS. To test this hypothesis, we used a task in which participants make a saccadic eye movement to a peripheral target and avoid a parafoveal nontarget while they are holding a color in working memory. Previous research with this task has shown that the parafoveal nontarget is more distracting when it matches the color being held in working memory. This effect should be enhanced in PSZ if their working memory representations are more intense. Consistent with this prediction, we found that the effect of a match between the distractor color and the memory color was larger in PSZ than in HCS. We also observed evidence that PSZ hyperfocused spatially on the region surrounding the fixation point. These results provide further evidence that some aspects of cognitive dysfunction in schizophrenia may be a result of a narrower and more intense focusing of processing resources.

Effect of task set-modulating attentional capture depends on the distractor cost in visual search: evidence from N2pc.

Previous studies have confirmed that attention can be modulated by the current task set while involuntarily captured by salient items. However, little is known on which factors the modulation of attentional capture is dependent on when the same stimuli with different task sets are presented. In the present study, participants conducted two visual search tasks with the same search arrays by varying target and distractor settings (color singleton as target, onset singleton as distractor, named as color task, and vice versa). Ipsilateral and contralateral color distractors resulted in two different relative saliences in two tasks, respectively. Both reaction times (RTs) and N2-posterior-contralateral (N2pc) results showed that there was no difference between ipsilateral and contralateral color distractors in the onset task. However, both RTs and the latency of N2pc showed a delay to the ipsilateral onset distractor compared with the contralateral onset distractor. Moreover, the N2pc observed under the contralateral distractor condition in the color task was reversed, and its amplitude was attenuated. On the basis of these results, we proposed a parameter called distractor cost (DC), computed by subtracting RTs under the contralateral distractor condition from the ipsilateral condition. The results suggest that an enhanced DC might be related to the modification of N2pc in searching for the color target. Taken together, these findings provide evidence that the effect of task set-modulating attentional capture in visual search is related to the DC.

The politics of color: preferences for Republican red versus Democratic blue.

The present study reveals that Election Day differentially affects the color preferences of US Republicans and Democrats. Voters' preferences for Republican red and Democratic blue were assessed, along with several distractor colors, on and around the 2010 interim and 2012 presidential elections. On non-Election Days, Republicans and Democrats preferred Republican red equally, and Republicans actually preferred Democratic blue more than Democrats did. On Election Day, however, Republicans' and Democrats' color preferences changed to become more closely aligned with their own party's colors. Republicans liked Republican red more than Democrats did, and no longer preferred Democratic blue more than Democrats did. These results are consistent with the hypothesis that color preferences are determined by people's preferences for correspondingly colored objects/entities (Palmer & Schloss in Proceedings of the National Academy of Sciences 107:8877-8882, 2010). They further suggest that color preferences are calculated at a given moment, depending on which color-object associations are currently most activated or salient. Color preferences are thus far more dynamic and context-dependent than has previously been believed.

The distractor positivity (Pd) signals lowering of attentional priority: Evidence from event‐related potentials and individual differences

We investigated the effects of task demands and individual differences on the allocation of attention. Using the same stimuli, participants indicated the orientation of a line contained in a shape singleton (identification task) or the presence of singletons (detection task). Shape singletons in the identification task elicited a contralateral negativity (N2pc) whereas shape singletons in the detection task elicited a contralateral positivity (Pd). We suggest that the reduction of attentional priority of a salient stimulus, reflected by the Pd, occurred more rapidly with the less demanding detection task. Further, fewer distractible participants showed a larger N2pc to lateral color distractors than highly distractible participants. We suggest that highly distractible participants developed compensatory mechanisms to suppress distracting stimuli.

Inhibitory deficits in trait anxiety: Increased stimulus-based or response-based interference?

Trait anxiety is associated with an impaired ability to inhibit task-irrelevant distractions. However, distractions may cause conflict at multiple stages within the information-processing stream, which may be resolved by different subsystems, depending on the type of conflict. Here, we contrasted two forms of conflict that have been distinguished in the literature: stimulus-stimulus (SS) versus stimulus-response (SR) competition. Across two experiments, participants completed a Stroop-like task that included distractor color words that could be either a different color promoting the same response as the target (SS interference) or a different color promoting a different response (SR interference). In line with previous studies, anxiety increased overall task-irrelevant distraction, measured by incongruent versus congruent reaction times. Importantly, this increase was driven solely by SR conflict, with no evidence of group differences in SS interference, despite clear within-subjects costs. These results clarify that trait anxiety may modulate inhibitory responses primarily by disrupting the resolution of response competition, while having little effect on stimulus conflict. Additionally, the results highlight the utility of distinguishing forms of conflict resolution, particularly in individual-difference approaches in which inhibition is impaired in a variety of clinical and nonclinical populations.

The attentional blink freezes spatial attention allocation to targets, not distractors: Evidence from human electrophysiology

Previous work found a significant reduction of the amplitude of the N2pc ERP component during the attentional blink in response to lateral visual targets, suggesting that the allocation of attention to visual targets is impaired during the attentional blink. Recent theorizing on the processes reflected by the N2pc suggests the possibility of distinct sets of neural mechanisms underlying its generation, one responsible for target activation, and one for distractor inhibition. To disentangle whether either or both of these mechanisms are impaired during the attentional blink, an RSVP sequence of circles, equidistant from fixation was used. The first target frame (T1) contained the same repeated target colour circle and target whereas the second target frame (T2) contained a distractor colour singleton as well as a target colour singleton. Only the target or only the distractor was presented at a lateral position; the other singleton was presented on the vertical midline so as not to elicit any event-related lateralization. Impaired T2 report accuracy at a short stimulus-onset asynchrony (SOA) was accompanied by a significant delay of the N2pc to lateral T2 targets when compared to a long SOA condition. No such delay was found when the lateralized stimulus was a distractor, suggesting that the attentional blink impacts attention allocation to targets, not distractors. We also observed a lateralized component earlier than the N2pc, a posterior contralateral positivity (Ppc) that did not depend on T1–T2 SOA and that was elicited by both lateral targets and distractors. We conclude that, contrary to N2pc, the Ppc likely reflects activity of bottom-up mechanisms responding unselectively to asymmetrical visual displays.

Neural Responses to Target Features outside a Search Array Are Enhanced during Conjunction but Not Unique-Feature Search

The visual world is typically too complex to permit full apprehension of its content from a single fixation. Humans therefore use visual search to direct attention and eye movements to locations or objects of interest in cluttered scenes. Psychophysical investigations have revealed that observers can select target elements from within an array of distractors on the basis of their spatial location or simple features, such as color. It remains unclear, however, how stimuli that lie outside the current search array are represented in the visual system. To investigate this, we recorded continuous neural activity using EEG while participants searched a foveal array of colored targets and distractors, and ignored irrelevant objects in the periphery. Search targets were defined either by a unique feature within the array or by a conjunction of features. Objects outside the array could match the target or distractor color within the array, or otherwise possessed a baseline (neutral) color present only in the periphery. The search array and irrelevant peripheral objects flickered at unique rates and thus evoked distinct frequency-tagged neural oscillations. During conjunction but not unique-feature search, target-colored objects outside the array evoked enhanced activity relative to distractor-colored and neutral objects. The results suggest that feature-based selection applies to stimuli at ignored peripheral locations, but only when central targets compete with distractors within the array. Distractor-colored and neutral objects evoked equivalent oscillatory responses, suggesting that feature-based selection at ignored locations during visual search arises exclusively from enhancement rather than suppression of neural activity.

Explaining efficient search for conjunctions of motion and form: Evidence from negative color effects

Dent, Humphreys, and Braithwaite (2011) showed substantial costs to search when a moving target shared its color with a group of ignored static distractors. The present study further explored the conditions under which such costs to performance occur. Experiment 1 tested whether the negative color-sharing effect was specific to cases in which search showed a highly serial pattern. The results showed that the negative color-sharing effect persisted in the case of a target defined as a conjunction of movement and form, even when search was highly efficient. In Experiment 2, the ease with which participants could find an odd-colored target amongst a moving group was examined. Participants searched for a moving target amongst moving and stationary distractors. In Experiment 2A, participants performed a highly serial search through a group of similarly shaped moving letters. Performance was much slower when the target shared its color with a set of ignored static distractors. The exact same displays were used in Experiment 2B; however, participants now responded "present" for targets that shared the color of the static distractors. The same targets that had previously been difficult to find were now found efficiently. The results are interpreted in a flexible framework for attentional control. Targets that are linked with irrelevant distractors by color tend to be ignored. However, this cost can be overridden by top-down control settings.

Tracking by location and features: Object correspondence across spatiotemporal discontinuities during multiple object tracking.

We examined whether surface feature information is utilized to track the locations of multiple objects. In particular, we tested whether surface features and spatiotemporal information are weighted according to their availability and reliability. Accordingly, we hypothesized that surface features should affect location tracking across spatiotemporal discontinuities. Three kinds of spatiotemporal discontinuities were implemented across five experiments: abrupt scene rotations, abrupt zooms, and a reduced presentation frame rate. Objects were briefly colored across the spatiotemporal discontinuity. Distinct coloring that matched spatiotemporal information across the discontinuity improved tracking performance as compared with homogeneous coloring. Swapping distinct colors across the discontinuity impaired performance. Correspondence by color was further demonstrated by more mis-selected distractors appearing in a former target color than distractors appearing in a former distractor color in the swap condition. This was true even when color never supported tracking and when participants were instructed to ignore color. Furthermore, effects of object color on tracking occurred with unreliable spatiotemporal information but not with reliable spatiotemporal information. Our results demonstrate that surface feature information can be utilized to track the locations of multiple objects. This is in contrast to theories stating that objects are tracked based on spatiotemporal information only. We introduce a flexible-weighting tracking account stating that spatiotemporal information and surface features are both utilized by the location tracking mechanism. The two sources of information are weighted according to their availability and reliability. Surface feature effects on tracking are particularly likely when distinct surface feature information is available and spatiotemporal information is unreliable.

Erratum to: Visual priming through a boost of the target signal: Evidence from saccadic landing positions

Searching for a target is slower when target features change from trial to trial than when they are repeated. Although heavily studied, it is still not wholly clear what process is influenced by such visual priming. Here, we introduce a new measure to study priming. When a target and distractor are in close proximity, fast saccades generally fall in between the two, a finding known as the global effect. We elicited global effect saccades to study the effects of repeating target or distractor colors on overt attention. Saccades landed closer to a target or distractor in the color of a previous target, suggesting that priming enhances target color signals. This was true even for the fastest eye movements, in the range of express saccades. Distractor color repetition, on the other hand, had no effect, at least in isolation. Visual priming is, we conclude, at least partly the result of boosting perceptual target signals.

Capture by fear revisited: An electrophysiological investigation

The present study, using a cueing paradigm, reexamined the claim of an attentional bias towards fearful faces. In Experiment 1, participants searched a target display for a letter in a specific colour. This target display was preceded by a noninformative cue display, which contained coloured boxes (one in the target colour and one in the distractor colour) or emotional faces (one fearful face and one neutral face). Each cue could appear in the same location as the target (validly cued) or different (invalidly cued). To determine whether the cues captured attention, we used an electrophysiological measure of spatial attention known as the N2pc effect. The target colour cue produced a substantial N2pc effect and a robust cue validity effect on behavioural data, indicating capture by stimuli that match what participants are looking for. However, neither effect was present for the task-irrelevant fearful face cue. These findings suggest that negative stimuli (such as fearful facial expressions) do not generally have the inherent power to capture spatial attention against our will. Experiment 2 showed that these same fearful faces could capture attention when fearful expressions became task relevant. Thus, the critical determinant of capture appears to be task relevance, rather than perceived threat.

Visual priming through a boost of the target signal: Evidence from saccadic landing positions

Searching for a target is slower when target features change from trial to trial than when they are repeated. Although heavily studied, it is still not wholly clear what process is influenced by such visual priming. Here, we introduce anew measure to study priming. When a target and distractor are in close proximity, fast saccades generally fall in between the two, a finding known as the global effect. We elicited global effect saccades to study the effects of repeating target or distractor colors on overt attention. Saccades landed closer to a target or distractor in the color of a previous target, suggesting that priming enhances target color signals. This was true even for the fastest eye movements, in the range of express saccades. Distractor color repetition, on the other hand, had no effect, at least in isolation. Visual priming is, we conclude, at least partly the result of boosting perceptual target signals [corrected].

Context-dependent sequential effects of target selection for action

Humans exhibit variation in behavior from moment to moment even when performing a simple, repetitive task. Errors are typically followed by cautious responses, minimizing subsequent distractor interference. However, less is known about how variation in the execution of an ultimately correct response affects subsequent behavior. We asked participants to reach toward a uniquely colored target presented among distractors and created two categories to describe participants' responses in correct trials based on analyses of movement trajectories; partial errors referred to trials in which observers initially selected a nontarget for action before redirecting the movement and accurately pointing to the target, and direct movements referred to trials in which the target was directly selected for action. We found that latency to initiate a hand movement was shorter in trials following partial errors compared to trials following direct movements. Furthermore, when the target and distractor colors were repeated, movement time and reach movement curvature toward distractors were greater following partial errors compared to direct movements. Finally, when the colors were repeated, partial errors were more frequent than direct movements following partial-error trials, and direct movements were more frequent following direct-movement trials. The dependence of these latter effects on repeated-task context indicates the involvement of higher-level cognitive mechanisms in an integrated attention-action system in which execution of a partial-error or direct-movement response affects memory representations that bias performance in subsequent trials. Altogether, these results demonstrate that whether a nontarget is selected for action or not has a measurable impact on subsequent behavior.

Response retrieval in a go/no-go priming-of-popout task

Priming of popout is the finding that singleton search is faster when features of a target and of nontargets are repeated across trials than when the features switch. Theoretical accounts suggest that intertrial repetition influences perceptual and attentional selection processes, episodic retrieval processes, or both. The present study combined a popout search task with a go/no-go task. In Experiment 1, the nontarget distractors in each display carried the go/no-go feature, and in Experiment 2, the texture of all items carried the go/no-go feature. Results showed that the go/no-go task moderated the intertrial repetition effects. In Experiment 1, the target color elicited retrieval of the preceding distractor color and associated no-go response, resulting in larger interference effects. In Experiment 2, the target color elicited retrieval of the preceding target color and no-go response, resulting in reduced facilitation effects. Additional results from both experiments showed that the colors in a search display also influenced target selection on the following trial. Taken together, the results of both experiments suggest that intertrial repetition influences both early selection and postselection retrieval processes.

Evaluation of a dichromatic color-appearance simulation by a visual search task

We used a visual search task to investigate the validity of the dichromatic simulation model proposed by Brettel et al. Although the dichromatic simulation could qualitatively predict reaction times for color-defective observers, the reaction times for color-defective observers tended to be longer than those of the trichromatic observers in Experiment 1. In Experiment 2, we showed that a reduction of purity excitation of simulated colors can provide a good prediction. Further, we propose an adaptive dichromatic simulation model based on the color differences between a simulated target color and simulated distractor colors in order to obtain a better quantitative prediction of reaction times in the visual search task for color defects.

Attentional capture during visual search is attenuated by target predictability: Evidence from the N2pc, Pd, and topographic segmentation

Attentional capture by salient distractors has been confirmed by the occurrence of an N2pc to the salient distractor. To clarify some failures to replicate this finding, we varied target predictability to induce different search modes. In the unpredictable target condition, the target shape varied randomly from trial to trial, favoring singleton detection mode. In the predictable target condition, the target shape remained the same in a block of trials, favoring feature search mode. With unpredictable targets, we observed an N2pc toward the salient color distractor, confirming attentional capture in singleton search mode. With predictable targets, there was no N2pc to the salient distractor, but a distractor positivity (Pd), suggesting distractor suppression. Also, differences emerged in the topographic segmentation of N2pc and Pd. Further, the amplitude of the N2pc toward the target was larger with predictable than with unpredictable targets.

Socially anxious individuals with low working memory capacity could not inhibit the goal-irrelevant information

Socially anxious individuals are interfered by distractors. Recent work has suggested that low working memory capacity and inappropriate temporary goal induce attention to distractors. We investigated the effects of working memory capacity and temporary goal on attention to distractors in social anxiety. Participants viewed a rapid serial visual presentation, in which participants reported the identity of a single target letter drawn in red. Distractors appeared before the target was presented. When the color of distractors was red (i.e., goal-relevant stimuli), low-capacity individuals were strongly interfered by the distractors compared to high-capacity individuals regardless of social anxiety. When the color of distractors was goal-irrelevant, low-capacity and high socially anxious individuals were strongly interfered by the distractors. These results suggest that socially anxious individuals with low working memory capacity could not inhibit the goal-irrelevant information and direct attention to distractors.

Learning to ignore salient color distractors during serial search: evidence for experience-dependent attention allocation strategies

Previous research has investigated whether visual salience (i.e., how much an item stands out) or perceptual load (i.e., display complexity) is the dominant factor in visual selective attention. The evidence has been mixed, with some findings supporting a dominant role for visual salience and some findings supporting a dominant role for perceptual load. However, the complex displays used to impose high perceptual load also introduce a third factor that has gone understudied until recently: the interplay between identity dilution and exposure duration. Adding display items to increase perceptual load dilutes a distractor's identity, which could decrease interference, but the task generally takes longer, which could increase distractor interference. To clarify how these factors interact, the present study used converging measures of distractor interference—both compatibility and singleton presence—to disambiguate effects due to salience, perceptual load, and identity dilution/exposure duration. Compatibility effects support perceptual load as the dominant factor, whereas singleton presence effects do not (Experiment 1). Consistent with salience-based mechanisms, significant distractor processing (both compatibility and presence effects) occurred under high perceptual load when singleton present trials preceded singleton absent trials (Experiment 2A). However, consistent with load-based mechanisms, non-significant compatibility effects occurred under high perceptual load when singleton absent trials preceded singleton present trials (Experiment 2B). Thus, the competition between salience-based and load-based mechanisms depended on the amount of prior experience with singleton present vs. absent displays, which in turn depended on the use of broad vs. narrow attentional allocation strategies. These experience-dependent effects provide further evidence that attention allocation strategies are contingent on factors such as task context and experience.

All set! Evidence of simultaneous attentional control settings for multiple target colors.

Although models of visual search have often assumed that attention can only be set for a single feature or property at a time, recent studies have suggested that it may be possible to maintain more than one attentional control setting. The aim of the present study was to investigate whether spatial attention could be guided by multiple attentional control settings for color. In a standard spatial cueing task, participants searched for either of two colored targets accompanied by an irrelevantly colored distractor. Across five experiments, results consistently showed that nonpredictive cues matching either target color produced a significant spatial cueing effect, while irrelevantly colored cues did not. This was the case even when the target colors could not be linearly separated from irrelevantly cue colors in color space, suggesting that participants were not simply adopting one general color set that included both target colors. The results could not be explained by intertrial priming by previous targets, nor could they be explained by a single inhibitory set for the distractor color. Overall, the results are most consistent with the maintenance of multiple attentional control settings.