Task-relevant Distractors Research Articles

Task-irrelevant filler items alter the dynamics of electrical brain activity during visual search.

In electroencephalography (EEG) studies of visual search, task-irrelevant fillers are included in displays to balance bottom-up stimulation across the visual field and generally considered as inconsequential for performance or EEG results. We examined the impact of fillers on target and distractor processing using lateralised event-related potentials (ERPs). Two task-relevant items (TRIs) were presented, with or without fillers. One TRI (target or target-colour distractor) was on the vertical midline and the other in a lateral position (left or right visual field) on an imaginary circle around fixation. An N2pc was elicited by lateral targets and task-relevant distractors, suggesting that attention was allocated to the lateral TRI because it possessed a target defining feature (colour). A Ptc was only elicited by lateral task-relevant distractors, in line with previous research suggesting that this component is associated with distractor processing. When fillers were also in the circular arrangement, alterations in performance and neural activity occurred. Fillers enhanced and delayed attentional deployment (N2pc) and delayed distractor processing (Ptc). Critically, we observed no difference in Ptc amplitude according to filler presence. Thus, if the Ptc reflects active suppression (or attentional disengagement), it was not required for fillers. ERPs were also modulated by the distance between TRIs (which could be separated by one or four filler positions), but differently according to the colour scheme (blue TRIs with grey fillers or vice versa). Our results suggest that fillers affect lateralised electrophysiological activity at multiple loci during visual search and should not be considered inconsequential.

Controlling the Flow of Distracting Information in Working Memory

Visual working memory (WM) must maintain relevant information, despite the constant influx of both relevant and irrelevant information. Attentional control mechanisms help determine which of this new information gets access to our capacity-limited WM system. Previous work has treated attentional control as a monolithic process-either distractors capture attention or they are suppressed. Here, we provide evidence that attentional capture may instead be broken down into at least two distinct subcomponent processes: (1) Spatial capture, which refers to when spatial attention shifts towards the location of irrelevant stimuli and (2) item-based capture, which refers to when item-based WM representations of irrelevant stimuli are formed. To dissociate these two subcomponent processes of attentional capture, we utilized a series of electroencephalography components that track WM maintenance (contralateral delay activity), suppression (distractor positivity), item individuation (N2pc), and spatial attention (lateralized alpha power). We show that new, relevant information (i.e., a task-relevant distractor) triggers both spatial and item-based capture. Irrelevant distractors, however, only trigger spatial capture from which ongoing WM representations can recover more easily. This fractionation of attentional capture into distinct subcomponent processes provides a refined framework for understanding how distracting stimuli affect attention and WM.

Closing-In Behavior and Motor Distractibility in Persons with Brain Injury.

This study investigates closing-in behavior (CIB), a phenomenon observed in graphic copying tasks when responses encroach upon or overlap the model. The behavior is most common amongst individuals with dementia and amongst pre-school children. We explored the relationship between CIB and the 'distractor effect' in reaching, whereby salient visual stimuli can influence the spatial trajectory of the reach. A group of individuals with overlap-CIB (n = 9), without CIB (n = 9) and healthy controls (HC; n = 6) underwent a task-irrelevant and a task-relevant distractors and the deviation of the movement trajectory towards the distractor location was measured in both tasks. Individuals with graphic CIB showed more distractor-directed veering during reaching than did individuals without CIB or HC, provided that the distractor was relevant for the reaching task. These results strengthen the relationship between CIB and the distractor effect and reinforce the hypothesis that CIB represents a disinhibited tendency to act towards the focus of attention.

Gaze Behavior in a Natural Environment with a Task-Relevant Distractor: How the Presence of a Goalkeeper Distracts the Penalty Taker.

Gaze behavior in natural scenes has been shown to be influenced not only by top–down factors such as task demands and action goals but also by bottom–up factors such as stimulus salience and scene context. Whereas gaze behavior in the context of static pictures emphasizes spatial accuracy, gazing in natural scenes seems to rely more on where to direct the gaze involving both anticipative components and an evaluation of ongoing actions. Not much is known about gaze behavior in far-aiming tasks in which multiple task-relevant targets and distractors compete for the allocation of visual attention via gaze. In the present study, we examined gaze behavior in the far-aiming task of taking a soccer penalty. This task contains a proximal target, the ball; a distal target, an empty location within the goal; and a salient distractor, the goalkeeper. Our aim was to investigate where participants direct their gaze in a natural environment with multiple potential fixation targets that differ in task relevance and salience. Results showed that the early phase of the run-up seems to be driven by both the salience of the stimulus setting and the need to perform a spatial calibration of the environment. The late run-up, in contrast, seems to be controlled by attentional demands of the task with penalty takers having habitualized a visual routine that is not disrupted by external influences (e.g., the goalkeeper). In addition, when trying to shoot a ball as accurately as possible, penalty takers directed their gaze toward the ball in order to achieve optimal foot-ball contact. These results indicate that whether gaze is driven by salience of the stimulus setting or by attentional demands depends on the phase of the actual task.

The exogenous and endogenous control of attentional focusing.

Selective visual attention involves prioritizing both the location (orienting) and distribution (focusing) of processing. To date, much more research has examined attentional orienting than focusing. One of the most well-established findings is that orienting can be exogenous, as when a unique change in luminance draws attention to a spatial location (e.g., Theeuwes in Atten Percept Psychophys 51:599-606, 1992; Yantis and Jonides in J Exp Psychol Hum Percept Perform 10:601, 1984), and endogenous, as when a red distractor shape diverts attention when one is looking for a red target (e.g., Bacon and Egeth in Percept Psychophys 55:485-496, 1994; Folk et al. in J Exp Psychol Hum Percept Perform 18:1030, 1992). Here we ask whether attentional focusing-the broadening and contracting of prioritized processing-is influenced by the same two factors. Our methodology involved a dual-stream attentional blink task; participants monitored two spatially separated streams of items for two targets that could appear unpredictably either in the same stream or in opposite streams. The spatial distribution of attention was assessed by examining second-target accuracy in relation to inter-target lag and target location (same or opposite streams). In Experiment 1, we found that attentional contracting was more rapid when the targets differed in luminance from the distractor items. In Experiments 2 and 3, we found that the rate of attentional contracting was slower when there were task-relevant distractors in the stream opposite the first target. These results indicate that the rate of attentional focusing, like orienting, can be modulated by both exogenous and endogenous mechanisms.

The necessity of visual attention to scene categorization: Dissociating "task-relevant" and "task-irrelevant" scene distractors.

The extent to which scenes are categorized and understood in the absence of attention has been the focus of a continuous debate over the last decade. Most studies investigating this question have used experimental paradigms in which participants explicitly searched for a certain scene category, or alternatively, scenes were task-irrelevant yet their identity was explicitly reported by participants. Although the first type of studies may have overestimated unattended scene processing, the latter type of studies may have underestimated scene processing due to the reliance on subjective response criteria and on working memory capacity limits. The present research examined scene processing by using an implicit, online behavioral measure which assessed the influence of both task-relevant (i.e., to-be-detected) and task-irrelevant distractor scenes on behavior. The effect of scene categorization was compared when scenes were fully attended (Experiment 1) versus when they were positioned in an unattended location and served as relevant/irrelevant distractors (Experiments 2 and 3). Our results demonstrated that in contrast to attended scenes, unattended distractor scenes which were not part of one's task-set were not automatically categorized and did not exert influence on performance. Critically, however, the very same scene distractors affected behavior when they contained a to-be-detected category, suggesting a qualitative dissociation between task-relevant and task-irrelevant distractors. Our study provides a systematic examination of scene distractor processing outside the focus of visual attention and a framework that may reconcile previous conflicting evidence. (PsycINFO Database Record

Contingent attentional capture across multiple feature dimensions in a temporal search task

The present study examined whether attention can be flexibly controlled to monitor two different feature dimensions (shape and color) in a temporal search task. Specifically, we investigated the occurrence of contingent attentional capture (i.e., interference from task-relevant distractors) and resulting set reconfiguration (i.e., enhancement of single task-relevant set). If observers can restrict searches to a specific value for each relevant feature dimension independently, the capture and reconfiguration effect should only occur when the single relevant distractor in each dimension appears. Participants identified a target letter surrounded by a non-green square or a non-square green frame. The results revealed contingent attentional capture, as target identification accuracy was lower when the distractor contained a target-defining feature than when it contained a nontarget feature. Resulting set reconfiguration was also obtained in that accuracy was superior when the current target's feature (e.g., shape) corresponded to the defining feature of the present distractor (shape) than when the current target's feature did not match the distractor's feature (color). This enhancement was not due to perceptual priming. The present study demonstrated that the principles of contingent attentional capture and resulting set reconfiguration held even when multiple target feature dimensions were monitored.

Evaluative pressure overcomes perceptual load effects.

Perceptual load has been found to be a powerful bottom-up determinant of distractibility, with high perceptual load preventing distraction by any irrelevant information. However, when under evaluative pressure, individuals exert top-down attentional control by giving greater weight to task-relevant features, making them more distractible from task-relevant distractors. One study tested whether the top-down modulation of attention under evaluative pressure overcomes the beneficial bottom-up effect of high perceptual load on distraction. Using a response-competition task, we replicated previous findings that high levels of perceptual load suppress task-relevant distractor response interference, but only for participants in a control condition. Participants under evaluative pressure (i.e., who believed their intelligence was assessed) showed interference from task-relevant distractor at all levels of perceptual load. This research challenges the assumptions of the perceptual load theory and sheds light on a neglected determinant of distractibility: the self-relevance of the performance situation in which attentional control is solicited.

Treatments for neuropathic pain differentially affect delayed matching accuracy by macaques: Effects of amitriptyline and gabapentin

Current clinical treatments for neuropathic pain include amitriptyline, a tricyclic antidepressant with mixed pharmacology that is also clinically reported to impair cognitive performance; and gabapentin, a compound that selectively interacts with α2δ-1 calcium channel subunits. Since few assessments of cognitive performance have been made in non-human primates with these marketed treatments, the purpose of this study was to determine their relative abilities to alter working memory as measured in mature macaques in their performance of a delayed matching-to-sample task. Four delay intervals of increasing duration provided increasing impairment in task accuracies during vehicle sessions. Administration of clinically relevant doses of amitriptyline significantly decreased task accuracy at the highest dose tested (3mg/kg). Administration of gabapentin increased mean task accuracy, though the effect was not statistically significant until intra-subject variability was reduced by selecting the individual best dose for each animal (which averaged 12.8mg/kg). Most of the effect was obtained during the presentation of long delay trials (18.2% above vehicle). Task improvement was sustained during sessions run 24h after gabapentin administration. In a series that used a task-relevant distractor to determine gabapentin’s effect on attention, drug treatment reversed distractor-impaired accuracy during long delay trials (25.4% above vehicle). The selective improvement in long delay accuracy in both paradigms suggests improvement in encoding or retention components of working memory. It is currently unclear whether the ability of acute administration of gabapentin to modestly improve working memory occurs by a mechanism that could be related to its anti-allodynic mechanism of action.

Short article: Distractor interference in focused attention tasks is not mediated by attention capture

Distractor stimuli possessing information that is relevant for a task (henceforth, task-relevant distractors) often interfere with task performance. The interference by task-relevant distractors is observed even when distractors are positioned outside the main attentional focus. We investigated whether such interference is due to an attention capture by the distractors. Participants responded to a target colour while ignoring word distractors positioned within (Experiment 1) or outside (Experiments 2 and 3) the attentional focus. The words carried task-relevant information in their colour and personally significant information in their content. Because personally significant information affects performance only when positioned in an attended region, it was used as a marker for the locus of the attentional focus. As expected, when distractors were attended, both task-relevant and personally significant information affected performance. However, when distractors were unattended, only task-relevant information caused interference, suggesting that attention did not shift to the distractors' location. We discuss possible accounts for interference effects in focused-attention tasks.

The contents of perceptual hypotheses: Evidence from rapid resumption of interrupted visual search

Observers can resume a previously interrupted visual search trial significantly more quickly than they can start a new search trial (Lleras, Rensink, & Enns, 2005). This rapid resumption of search is possible because evidence accumulated during the previous exposure, a perceptual hypothesis, can carry over to a subsequent presentation. We present four interrupted visual search experiments in which the content of the perceptual hypotheses used during visual search trials was characterized. These experiments suggest that prior to explicit target identification, observers have accumulated evidence about the locations, but not the identities, of local, task-relevant distractors, as well as preliminary evidence for the identity of the target. Our results characterize the content of perceptual search hypotheses and highlight the utility of interrupted search for studying online search processing prior to target identification.

Attention to self-referential stimuli: Can I ignore my own face?

Auto-referential materials (i.e., the own name) have been described as particularly prone to capture attention. Some recent studies have questioned this view and shown that these own name effects are temporary and appear only in specific conditions: when enough resources are available (Harris, C. R., & Pashler, H. (2004). Attention and the processing of emotional words and names: Not so special after all. Psychological Science, 15, 171–178) or when the own name is presented within the focus of attention if it is a task-irrelevant stimulus (Gronau, N., Cohen, A., & Ben-Shakhar, G. (2003). Dissociations of personally significant and task-relevant distractors inside and outside the focus of attention: A combined behavioral and psychophysiological study. Journal of Experimental Psychology: General, 132, 512–529). In the present study, a stimulus that is unique to each individual was used: the self-face. In Experiment 1, the self-face produced a temporary distraction when presented at fixation during a digit-parity task. However, this distraction was not different from that triggered by another highly familiar face. In Experiment 2, the self-face failed to produce interference when presented outside the focus of attention. These results confirm recent findings showing that auto-referential materials do not automatically summon attention and have a distractive power only in specific conditions.

Failures to ignore entirely irrelevant distractors: The role of load.

In daily life (e.g., in the work environment) people are often distracted by stimuli that are clearly irrelevant to the current task and should be ignored. In contrast, much applied distraction research has focused on task interruptions by information that requires a response and therefore cannot be ignored. Moreover, the most commonly used laboratory measures of distractibility (e.g., in the response-competition and attentional-capture paradigms), typically involve distractors that are task relevant (e.g., through response associations or location). A series of experiments assessed interference effects from stimuli that are entirely unrelated to the current task, comparing the effects of perceptual load on task-irrelevant and task-relevant (response competing) distractors. The results showed that an entirely irrelevant distractor can interfere with task performance to the same extent as a response-competing distractor and that, as with other types of distractors, the interfering effects of the irrelevant distractors can be eliminated with high perceptual load in the relevant task. These findings establish a new laboratory measure of a form of distractibility common to everyday life and highlight load as an important determinant of such distractibility.

Enhanced attention in rhesus monkeys as a common factor for the cognitive effects of drugs with abuse potential.

One of the common neurochemical features of many drugs of abuse is their ability to directly or indirectly enhance dopaminergic activity in the brain, particularly within the ventral tegmental-nucleus accumbens pathway. Dopaminergic pathways in the frontal and limbic cortex also may be targets for these agents, where pharmacological effects could result in heightened attention and/or support self-administration behavior. The purpose of this study was to determine whether drugs from differing pharmacological classes that exhibit abuse potential would share the ability to counter distractability in the delayed matching task. Well trained mature macaques performed a computer-assisted delayed matching-to-sample task which included trials associated with three delay intervals and randomly interspersed task-relevant distractors. Drug regimens included four to five doses and subjects were tested no more than twice per week. All but one of the six compounds (tomoxetine), on average, increased task accuracy for either non-distractor or distractor trials. It was evident that for several compounds, doses required to improve accuracy for non-distractor trials were routinely greater than the doses required to improve accuracy for distractor trials. Data for the individualized Best dose (based upon the subject's optimal level of accuracy during distractor trials) revealed statistically significant distractor-related improvements in task accuracy for the same five compounds. The relative efficacy for reversing distractor-induced decrements in task accuracy was estimated by the level of improvement with respect to baseline: nomifensine (31%)>nicotine (22%) approximately morphine (19%) approximately caffeine (19%) approximately methylphenidate (22%) >tomoxetine (9%). Tomoxetine (noradrenergic preferring) was the only compound that did not produce a significant improvement in accuracy. These results provide pharmacological support for the concept that attentional mechanisms may play an important role in the "environmental" associative aspects of drug seeking behavior, and as such they may provide the basis for treatment strategies aimed at preventing relapse in detoxified addicts.

Interference from multi-dimensional objects during feature and conjunction discriminations.

Feature discrimination performance within an attended object and interference from irrelevant, multi-dimensional objects (distractors) were examined in a two-choice, response compatibility paradigm. Results showed that the amount of interference by multi-dimensional distractors was dependent on three factors: (1) the discriminability of the incompatible, task-relevant distractor features; (2) the number of incompatible, task-relevant distractor features; and (3) whether the task-relevant, incompatible features matched the task goals. The most interesting finding was that additive priming effects were found for multiple, task-relevant features that matched the task goals, whether these features were present in the attended object or in the ignored object. Models that assume that each task-relevant feature primes its corresponding decision/response asynchronously and that this priming is combined to meet a decision/response criterion (at least when attended) can account for distractor interference during conjunction discriminations. Implications of these findings for feature integration models, template models, and a response selection model are discussed.

The effect of variability of unattended information on global and local processing: evidence for lateralization at early stages of processing

Visual objects can often be analyzed as hierarchical in structure, composed of local elements that are spatially arranged to form a global shape. The brain mechanisms involved in the analysis of hierarchical figures have been under considerable scrutiny in recent years, and one of the many interesting features that have emerged is that there is an asymmetry across the two hemispheres for global (right hemisphere) vs local (left hemisphere) processing. Event-related potentials (ERP) were used to examine selective attention to global or local levels of hierarchical figures to determine the stage of processing at which the asymmetry first emerges. Two conditions were tested, one in which unattended information was variable from trial to trial, and one in which it was not. The variability of unattended information influenced the lateralization of processing. Presentation of invariable, neutral distractors resulted in global/local processing asymmetries at early stages (P1). In contrast, presentation of variable, task-relevant distractors resulted in processing asymmetries that occurred at much later stages (N2). Our hypothesis is that lateralized enhancement of neural populations in extrastriate cortex results from both selective attention to locations in the visual field, as well as selective attention to global or local information. We suggest that unattended information that varies from trial to trial is processed in parallel with attended information, masking hemisphere biases for local vs global information at early stages of processing.