Irrelevant Distractors Research Articles

Detection of object displacement during a saccade is prioritized by the oculomotor system.

The human eye-movement system is equipped with a sophisticated updating mechanism that can adjust for large retinal displacements produced by saccadic eye movements. The nature of this updating mechanism is still highly debated. Previous studies have demonstrated that updating can occur very rapidly and is initiated before the start of a saccade. In the present study, we used saccade curvature to demonstrate that the oculomotor system is tuned for detecting object displacements during saccades. Participants made a sequence of saccades while ignoring an irrelevant distractor. Curvature of the second saccade relative to the distractor was used to estimate the time course of updating. Saccade curvature away from the presaccadic location of the distractor emerged as early as 80 ms after the first saccade when the distractor was displaced during a saccade. This is about 50 ms earlier than when a distractor was only present before a saccade, only present after a saccade, or remained stationary across a saccade. This shows that the oculomotor system prioritizes detection of object displacements during saccades, which may be useful for guiding corrective saccades. The results also challenge previous views by demonstrating the additional role of postsaccadic information in updating target-distractor competition across saccades.

Cost-benefit trade-offs in decision-making and learning.

Value-based decision-making involves trading off the cost associated with an action against its expected reward. Research has shown that both physical and mental effort constitute such subjective costs, biasing choices away from effortful actions, and discounting the value of obtained rewards. Facing conflicts between competing action alternatives is considered aversive, as recruiting cognitive control to overcome conflict is effortful. Moreover, engaging control to proactively suppress irrelevant information that could conflict with task-relevant information would presumably also be cognitively costly. Yet, it remains unclear whether the cognitive control demands involved in preventing and resolving conflict also constitute costs in value-based decisions. The present study investigated this question by embedding irrelevant distractors (flanker arrows) within a reversal-learning task, with intermixed free and instructed trials. Results showed that participants learned to adapt their free choices to maximize rewards, but were nevertheless biased to follow the suggestions of irrelevant distractors. Thus, the perceived cost of investing cognitive control to suppress an external suggestion could sometimes trump internal value representations. By adapting computational models of reinforcement learning, we assessed the influence of conflict at both the decision and learning stages. Modelling the decision showed that free choices were more biased when participants were less sure about which action was more rewarding. This supports the hypothesis that the costs linked to conflict management were traded off against expected rewards. During the learning phase, we found that learning rates were reduced in instructed, relative to free, choices. Learning rates were further reduced by conflict between an instruction and subjective action values, whereas learning was not robustly influenced by conflict between one’s actions and external distractors. Our results show that the subjective cognitive control costs linked to conflict factor into value-based decision-making, and highlight that different types of conflict may have different effects on learning about action outcomes.

Individual differences in parietal and frontal cortex structure predict dissociable capacities for perception and cognitive control

Capacity limits in perception can lead to failures of awareness in situations that overload capacity, resulting in various phenomena of ‘inattentional blindness’. In contrast, capacity limits in cognitive control over attention by working memory lead to increased processing of irrelevant distractors (reduced inattentional blindness). Here, using Voxel-Based Morphometry combined with Principal Components Analysis, we establish distinct brain-structural correlates of perceptual capacity, dissociable from those of cognitive control. Perceptual capacity was measured as the principal component accounting for variance across tasks of multiple object tracking, change blindness and rapid visual enumeration (i.e. ‘subitizing’). Cognitive control capacity was measured as the principal component underlying performance of three different complex working memory span tasks (involving spatial, semantic and numerical domains). Volumetric differences in the right Inferior Parietal Lobule (IPL) were predictive of individual differences in perceptual capacity, while volumetric differences in left Middle Frontal Gyrus (MFG) (as well as lateral frontal and posterior cingulate cortex in a non-parametric analysis) were predictive of individual differences in cognitive control capacity. IPL remained a significant predictor of perceptual capacity when controlling for variance accounted for by cognitive control capacity and vice versa for the neural correlates of cognitive control. These results suggest that perceptual and cognitive control capacities represent dissociable and lasting, trait-like attributes which can be predicted from distinct signatures in regional grey matter.

Orbitofrontal cortex is selectively activated in a primate model of attentional bias to cocaine cues

Attentional bias to drug-associated cues correlates with extent of current use, and risk of relapse among those attempting abstinence. Electroencephalogram (EEG) and functional imaging measures in clinical studies have previously investigated the neural basis of attentional bias, but the lack of animal models precluded investigation at the single-unit level. To complement results obtained from clinical studies, we have employed a non-human primate model of attentional bias to cocaine cues while simultaneously recording single-unit activity in cortical and striatal regions implicated in reward processing. Rhesus macaques conditioned to associate particular colors with cocaine or water reward performed an attentional bias task, in which those colors served as irrelevant distractors. Concurrently, multiple electrode arrays for recording single-unit activity were acutely implanted into the orbitofrontal cortex, anterior cingulate cortex, dorsal anterior striatum, and ventral striatum. As in clinical studies, attentional bias was indicated by elongated response times on trials with cocaine-associated distractors compared with trials with water-associated, or control unconditioned distractors. In both animals studied, across an unbiased sample of neurons, the orbitofrontal cortex differentiated distractor condition by the proportion of single-units activated, as well as by population response. In one of the two, the anterior cingulate cortex did as well, but neither striatal region did in either animal. These direct measures of single-unit activity in a primate model complement clinical imaging observations suggesting that cortical mechanisms, especially in orbitofrontal cortex, are likely involved in attentional bias to cocaine-associated environmental cues.

Evoked Response Strength in Primary Auditory Cortex Predicts Performance in a Spectro-Spatial Discrimination Task in Rats.

The extent to which the primary auditory cortex (A1) participates in instructing animal behavior remains debated. Although multiple studies have shown A1 activity to correlate with animals' perceptual judgments (Jaramillo and Zador, 2011; Bizley et al., 2013; Rodgers and DeWeese, 2014), others have found no relationship between A1 responses and reported auditory percepts (Lemus et al., 2009; Dong et al., 2011). To address this ambiguity, we performed chronic recordings of evoked local field potentials (eLFPs) in A1 of head-fixed female rats performing a two-alternative forced-choice auditory discrimination task. Rats were presented with two interleaved sequences of pure tones from opposite sides and had to indicate the side from which the higher-frequency target stimulus was played. Animal performance closely correlated (rrm = 0.68) with the difference between the target and distractor eLFP responses: the more the target response exceeded the distractor response, the better the animals were at identifying the side of the target frequency. Reducing the evoked response of either frequency through stimulus-specific adaptation affected performance in the expected way: target localization accuracy was degraded when the target frequency was adapted and improved when the distractor frequency was adapted. Target frequency eLFPs were stronger on hit trials than on error trials. Our results suggest that the degree to which one stimulus stands out over others within A1 activity may determine its perceptual saliency for the animals and accordingly bias their behavioral choices.SIGNIFICANCE STATEMENT The brain must continuously calibrate the saliency of sensory percepts against their relevance to the current behavioral goal. The inability to ignore irrelevant distractors characterizes a spectrum of human attentional disorders. Meanwhile, the connection between the neural underpinnings of stimulus saliency and sensory decisions remains elusive. Here, we record local field potentials in the primary auditory cortex of rats engaged in auditory discrimination to investigate how the cortical representation of target and distractor stimuli impacts behavior. We find that the amplitude difference between target- and distractor-evoked activity predicts discrimination performance (rrm = 0.68). Specific adaptation of target or distractor shifts performance either below or above chance, respectively. It appears that recent auditory history profoundly influences stimulus saliency, biasing animals toward diametrically-opposed decisions.

Transcranial direct current stimulation of posterior temporal cortex modulates electrophysiological correlates of auditory selective spatial attention in posterior parietal cortex

Speech perception in “cocktail-party” situations, in which a sound source of interest has to be extracted out of multiple irrelevant sounds, poses a remarkable challenge to the human auditory system. Studies on structural and electrophysiological correlates of auditory selective spatial attention revealed critical roles of the posterior temporal cortex and the N2 event-related potential (ERP) component in the underlying processes. Here, we explored effects of transcranial direct current stimulation (tDCS) to posterior temporal cortex on neurophysiological correlates of auditory selective spatial attention, with a specific focus on the N2. In a single-blind, sham-controlled crossover design with baseline and follow-up measurements, monopolar anodal and cathodal tDCS was applied for 16 min to the right posterior superior temporal cortex. Two age groups of human subjects, a younger (n = 20; age 18–30 yrs) and an older group (n = 19; age 66–77 yrs), completed an auditory free-field multiple-speakers localization task while ERPs were recorded. The ERP data showed an offline effect of anodal, but not cathodal, tDCS immediately after DC offset for targets contralateral, but not ipsilateral, to the hemisphere of tDCS, without differences between groups. This effect mainly consisted in a substantial increase of the N2 amplitude by 0.9 μV (SE 0.4 μV; d = 0.40) compared with sham tDCS. At the same point in time, cortical source localization revealed a reduction of activity in ipsilateral (right) posterior parietal cortex. Also, localization error was improved after anodal, but not cathodal, tDCS. Given that both the N2 and the posterior parietal cortex are involved in processes of auditory selective spatial attention, these results suggest that anodal tDCS specifically enhanced inhibitory attentional brain processes underlying the focusing onto a target sound source, possibly by improved suppression of irrelevant distracters.

Neurophysiological evidence of impaired attention and working memory in untreated hematologic cancer patients

ObjectiveNeuroimaging studies of hematologic cancer patients report altered activity in dorsal attention and central executive networks. To determine the consequences of these altered brain networks, we evaluated neurophysiological correlates of attention and working memory in hematologic cancer patients prior to initiating treatment. MethodsHematologic cancer patients (19–80 years) were excluded for premorbid cognitive impairment, prior non-hematologic cancer diagnosis, and prior chemotherapy. Attention was manipulated by presenting an irrelevant spatial cue prior to visual search displays. Working memory was manipulated by presenting irrelevant distractors within memory displays. Electroencephalogram was recorded during task performance. ResultsPatients (n = 28) and controls (n = 15) were balanced on age, gender, and education. Spatial cues evoked larger N2pc amplitudes, a correlate of spatial attention, in patients than controls (p < .05; Cohen’s d > 0.7). Memory distractors evoked larger contralateral delay activity amplitudes, a correlate of working memory load, in patients (p = .028; Cohen’s d = 1.1) but not controls (p = .64). ConclusionsPrior to initiating treatment, hematologic cancer patients demonstrated poor control over spatial attention and working memory, consistent with altered dorsal attention and central executive network activity. SignificanceHematologic cancer patients may be at a higher risk for selecting, processing, and storing distracting information that would compete with more immediate goal-related behaviors.

Attention, mindwandering, and mood.

We tested the hypothesis that mindwandering and external distraction are both manifestations of a common state of reduced attention focus, and examined how both relate to reported level of happiness. We conducted real-time sampling of people's experience of mindwandering, irrelevant distraction (e.g. by music, phone, etc.), and happiness levels, in two studies with 524 people undertaking common daily-life activities. All irrelevant external distractions were positively correlated with mindwandering. Indeed mindwandering duration could be predicted from the reported duration of external distraction, when controlling for a range of background variables. An exploratory factor analysis of mindwandering and distraction reports suggested a single underlying construct. In addition, duration of irrelevant distraction by both mobile phones and mindwandering was significantly associated with reduced reported levels of happiness. The results are consistent with the hypothesis that that a state of reduced attention focus underlies both mindwandering and distractibility and clarify the link with happiness.

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).

Perceptual inhibition of emotional interference in children

In daily life, when a bee approaches us while we are sitting in the garden, we must pay attention to that threatening stimulus and give an appropriate response. However, if this bee approaches us while riding a bike, we must inhibit that distractor to avoid an accident. In this case, avoiding the interference of an emotional stimuli and continuing with the task should be preferential. In general, perceptual inhibition is responsible for controlling and suppressing the environmental distractions that interrupt the course of the realization of a goal. In this study, 435 children performed a modified flanker task with entirely irrelevant emotional and neutral stimuli in order to assess perceptual inhibition in contexts with high and low emotional salience. The results showed that entirely irrelevant distractors affected performance, but that there were no significant differences according to whether these distractors were emotionally salient or neutral. These results constitute a first approach to the problem of emotional interference in children considering the multidimensional approach of inhibition.

Object-based biased competition during covert spatial orienting.

Biased-competition models assert that spatial attention facilitates visual perception by biasing competitive interactions in favor of relevant input. In line with this view, past work has shown that the benefits of covert spatial attention are greatest when targets must compete with interfering stimuli. Here we propose a boundary condition for the resolution of interference via exogenous attention: Attention resolves visual interference between targets and distractors, but only when they can be individuated into distinct representations. Thus, we propose that biased competition may be object-based. We replicated previous observations of larger attention effects when targets were flanked by irrelevant distractors (interference-present displays) than when targets were presented alone (interference-absent displays). Critically, we then showed that this amplification of cueing effects in the presence of interference is eliminated when strong crowding hampers individuation of the targets and distractors. Likewise, when targets were embedded within a noise mask that did not evoke the percept of an individuated distractor, the attention effects were equivalent across noise and lone-target displays. Thus, we conclude that exogenous spatial attention resolves interference in an object-based fashion that depends on the perception of individuated targets and distractors.

Kanizsa-figure object completion gates selection in the attentional blink.

Previous work has demonstrated that perceptual grouping modulates the selectivity of attention across space. By contrast, how grouping influences the allocation of attention over time is much less clear. This study investigated this issue, using an attentional blink (AB) paradigm to test how grouping influences the initial selection and the subsequent short-term memory consolidation of a target. On a given trial, two red Kanizsa-type targets (T1 and T2) with varying grouping strength were embedded in a rapid serial visual presentation stream of irrelevant distractors. Our results showed the typical AB finding: impaired identification of T2 when presented close in time following T1. Moreover, the AB was modulated by the T2 grouping-independently of the T1 structure-with stronger grouping leading to a decreased AB and overall higher performance. Conversely, a reversed pattern, namely an increased AB with increasing grouping strength was observed when the Kanizsa figure was not task-relevant. Together, these findings suggest that the grouping benefit emerges at early perceptual stages, automatically drawing attentional resources, thereby leading to either sustained benefits or transient costs-depending on the task-relevance of the grouped object. This indicates that grouping modulates processing of objects in time.

Implications of capacity in the classroom: Simplifying tasks for autistic children may not be the answer

BackgroundResearch has demonstrated evidence for increased perceptual capacity in autism: autistic people can process more information at any given time than neurotypical individuals. The implications of this for educating autistic pupils have not been investigated. For example, this ability to process more information at any given time may explain why autistic children sometimes process more peripheral task-irrelevant information than neurotypical individuals (e.g. in background classroom wall-displays). AimsThe current study assessed the impact of different types of background information on autistic and non-autistic children’s ability to perform a learning task. Methods and ProceduresAutistic (N = 23) and non-autistic (N = 50) children took part in a computer-based task designed to simulate a lesson. They watched three videos of a teacher telling a story, each with a different background condition: blank, relevant images, or irrelevant images. Outcomes and ResultsWhen the visual display contained story-relevant information, both groups recalled background information in addition to the central story. When the background displays were irrelevant to the story, autistic children recalled more background information than their neurotypical peers, yet maintained their ability to recall information from the central story. Conclusion and ImplicationsThe current study suggests that pupils’ perceptual capacity– including those on the autistic spectrum - can indeed be capitalised on to support learning in the classroom. To do so, however, we must ensure that the child can use their capacity for task-relevant processing, rather than irrelevant distractions.

How feature relationships influence attention and awareness: Evidence from eye movements and EEG.

Many everyday tasks require selecting relevant objects in the visual field while ignoring irrelevant information. A widely held belief is that attention is tuned to the exact feature value(s) of a sought-after target object (e.g., color, shape). In contrast, subsequent studies have shown that attentional orienting (capture) is often determined by the relative feature(s) that the target has relative to other irrelevant items surrounding (e.g., redder, larger). However, it is unknown whether conscious awareness is also determined by relative features. Alternatively, awareness could be more strongly determined by exact feature values, which seem to determine dwelling on objects. The present study examined eye movements in a color search task with different types of irrelevant distractors to test (a) whether dwelling is more strongly influenced by exact feature matches than relative matches, and (b) which of the processes (capture vs. dwelling) is more important for conscious awareness of the distractor. A second experiment used an electrophysiological marker of attention (N2pc in the electroencephalogram of participants) to test whether the results generalize to covert attention shifts. As expected, the results revealed that the initial capture of attention was strongest for distractors matching the relative color of the target, whereas similarity to the target was the most important determiner for dwelling. Awareness was more strongly determined by the initial capture of attention than dwelling. These results provide important insights into the interplay of attention and awareness and highlight the importance of considering relative, context-dependent features in theories of awareness. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Differential activation of a central inhibition system by motion and colour distractors

ABSTRACTThe selection of relevant stimuli is partially achieved through inhibition of irrelevant distractors. Using the distractor induced blindness (DIB) paradigm, we investigated whether these inhibitory processes depend on the feature dimension that is used to define distractors. Following a pilot study that found motion and colour targets to be comparably salient, we analysed distractor effects of those two feature dimensions. In both feature dimensions, an inhibition effect depended on the number of distractors. Colour, however, was more sensitive to distractor episodes as compared to motion: The level of inhibition was more pronounced, and its activation required less distractors. The results of a control experiment provided further evidence that, in fact, the feature dimension -instead of design differences between tasks- is responsible for this observation. The dimension-sensitive bias in the activation of a central inhibition system may be attributed to a differential processing of visual signals, depending on their behavioural relevance.

The power of negative thinking: Paradoxical but effective ignoring of salient-but-irrelevant stimuli with a spatial cue

ABSTRACTA uniquely coloured singleton among other uniformly coloured stimuli can function as a powerful attractor of attention. However, top-down attentional mechanisms are also powerful, and there are circumstances in which they can suppress irrelevant distractors. The current study tested whether an endogenous spatial cue indicating the location of a salient colour singleton distractor can eliminate involuntary attentional allocation to such a stimulus. When an arrow cue indicated a to-be-ignored location that would never contain a target but would contain a colour singleton distractor, a significant singleton capture effect was eliminated on ignore trials regardless of the consistency of the singleton colour in Experiments 1 and 2. In Experiment 3, a consistent colour singleton was used without a spatial cue. Participants were not able to suppress singleton distractors in the absence of a cue. However, in Experiments 1 & 2, the status of a letter inscribed in the singleton (i.e., whether it is compatible or incompatible with the target of the search) did affect reaction time on ignore trials. If the compatibility effect indicates a shift of attention to the singleton, the data may mean that, with a spatial cue, participants inhibit a cued location by first selecting the location and then rapidly disengaging from it.

Turning distractors into targets increases the congruency sequence effect

The congruency effect in distractor-interference tasks is typically smaller after incongruent trials than after congruent trials. Current views posit that this congruency sequence effect (CSE) reflects control processes that come into play when an irrelevant distractor cues a different response than a relevant target. However, the CSE is counterintuitively larger in the prime-probe task when the prime is occasionally a second target than when the prime is more frequently a distractor. In the present study, we investigated whether this effect occurs because the appearance of an occasional prime target (a) constitutes a rare, unexpected event that triggers heightened control or (b) allows participants to use the same task set (i.e., stimulus-response mapping) for the prime and probe in each trial. Consistent with the latter hypothesis, we observed this effect in Experiment 1 even when the critical trial types appeared equally often. Further, in Experiment 2, we extended this finding while ruling out perceptual differences between conditions as an alternative account. These findings provide novel support for the task set hypothesis and reveal that the CSE reflects control processes that do more than minimize distraction from irrelevant stimuli.

Target-distractor competition cannot be resolved across a saccade

When a distractor is presented in close spatial proximity to a target, a saccade tends to land in between the two objects rather than on the target. This robust phenomenon (also referred to as the global effect) is thought to reflect unresolved competition between target and distractor. It is unclear whether this landing bias persists across saccades since a saccade displaces the retinotopic representations of target and distractor. In the present study participants made successive saccades towards two saccadic targets which were presented simultaneously with an irrelevant distractor in close proximity to the second saccade target. The second saccade was either visually-guided or memory-guided. For the memory-guided trials, the second saccade showed a landing bias towards the location of the distractor, despite the disappearance of the distractor after the first saccade. In contrast, for the visually-guided trials, the bias was corrected and the landing bias was eliminated, even for saccades with the shortest intersaccadic intervals. This suggests that the biased saccade plan was remapped across the first saccade. Therefore, we conclude that the target-distractor competition was not resolved across a saccade, but can be resolved based on visual information that is available after a saccade.

Oculomotor capture reveals trial-by-trial neural correlates of attentional guidance by contents of visual working memory

Evidence from attentional and oculomotor capture, contingent capture, and other paradigms suggests that mechanisms supporting human visual working memory (VWM) and visual attention are intertwined. Features held in VWM bias guidance toward matching items even when those features are task irrelevant. However, the neural basis of this interaction is underspecified. Prior examinations using fMRI have primarily relied on coarse comparisons across experimental conditions that produce varying amounts of capture. To examine the neural dynamics of attentional capture on a trial-by-trial basis, we applied an oculomotor paradigm that produced discrete measures of capture. On each trial, subjects were shown a memory item, followed by a blank retention interval, then a saccade target that appeared to the left or right. On some trials, an irrelevant distractor appeared above or below fixation. Once the saccade target was fixated, subjects completed a forced-choice memory test. Critically, either the target or distractor could match the feature held in VWM. Although task irrelevant, this manipulation produced differences in behavior: participants were more likely to saccade first to an irrelevant VWM-matching distractor compared with a non-matching distractor – providing a discrete measure of capture. We replicated this finding while recording eye movements and scanning participants' brains using fMRI. To examine the neural basis of oculomotor capture, we separately modeled the retention interval for capture and non-capture trials within the distractor-match condition. We found that frontal activity, including anterior cingulate cortex and superior frontal gyrus regions, differentially predicted subsequent oculomotor capture by a memory-matching distractor. Other regions previously implicated as involved in attentional capture by VWM-matching items showed no differential activity across capture and non-capture trials, even at a liberal threshold. Our findings demonstrate the power of trial-by-trial analyses of oculomotor capture as a means to examine the underlying relationship between VWM and attentional guidance systems.

Reconceptualizing perceptual load as a rate problem: The role of time in the allocation of selective attention.

In the literature about allocation of selective attention, a widely studied question is when will attention be allocated to information that is clearly irrelevant to the task at hand. The present study, by using convergent evidence, demonstrated that there is a trade-off between quantity of information present in a display and the time allowed to process it. Specifically, whether or not there is interference from irrelevant distractors depends not only on the amount of information present, but also on the amount of time allowed to process that information. When processing time is calibrated to the amount of information present, irrelevant distractors can be selectively ignored successfully. These results suggest that the perceptual load in the load theory of selective attention (i.e., Lavie, 2005) should be thought about as a dynamic rate problem rather than a static capacity limitation. The authors thus propose that rather than conceiving of perceptual load as a quantity of information, they should consider it as a quantity of information per unit of time. In other words, it is the relationship between the quantity of information in the task and the time for processing the information that determines the allocation of selective attention. Thus, the present findings extended load theory, allowing it to explain findings that were previously considered as counter evidence of load theory. (PsycINFO Database Record