Distractor Location Research Articles

Dynamics of Saccade Trajectory Modulation by Distractors: Neural Activity Patterns in the Frontal Eye Field.

The sudden appearance of a visual distractor shortly before saccade initiation can capture spatial attention and modulate the saccade trajectory in spite of the ongoing execution of the initial plan to shift gaze straight to the saccade target. To elucidate the neural correlates underlying these curved saccades, we recorded from single neurons in the frontal eye field (FEF) of two male rhesus monkeys shifting gaze to a target while a distractor with the same eccentricity appeared either left or right of the target at various delays after target presentation. We found that the population level of pre-saccadic activity of neurons representing the distractor location encoded the direction of the saccade trajectory. Stronger activity occurred when saccades curved toward the distractor, and weaker when saccades curved away. This relationship held whether the distractor was ipsilateral or contralateral to the recorded neurons. Meanwhile, visually responsive neurons showed asymmetrical patterns of excitatory responses that varied with the location of the distractor and the duration of distractor processing relating to attentional capture and distractor inhibition. During earlier distractor processing, neurons encoded curvature towards the distractor. During later distractor processing, neurons encoded curvature away from the distractor. This was observed when saccades curved away from distractors contralateral to the recording site and when saccades curved towards distractors ipsilateral to the recording site. These findings indicate that saccadic motor planning involves dynamic push-pull hemispheric interactions producing attraction or repulsion for potential but unselected saccade targets.Significant Statement This study not only advances our understanding of oculomotor function in dynamic environments but also has potential clinical relevance for diagnosing and understanding disorders characterized by abnormal saccade trajectories. Our research elucidates the neural mechanisms behind saccade trajectories that are not always linear due to the brain's integration of multiple visual cues and/or motor plans. By analyzing the frontal eye field (FEF) activity in rhesus monkeys, we found that saccade directionality and timing are influenced by the interaction between FEF visual neurons representing target and distractor stimuli. The FEF's role extends beyond a winner-takes-all approach, incorporating saccade vector averaging computations that produce curved saccades. Furthermore, ipsilateral visual neurons encode distractor suppression that drives curvature away from the distractor.

The Role of Spatial Reference Frame in Implicit Distractor Location Learning

The Role of Spatial Reference Frame in Implicit Distractor Location Learning

Distractor location frequencies better account for the instantiation of learned distractor suppression than do reinforcement learning prediction errors

Distractor location frequencies better account for the instantiation of learned distractor suppression than do reinforcement learning prediction errors

Dynamic suppression of likely distractor locations: Task-critical modulation

ABSTRACT When a distractor frequently appears in a certain region of a search display, it interferes less with performance, reflecting learned distractor suppression. While this effect is well established, it remains unknown whether this suppression is ongoing (tonic) or deactivated upon task completion (phasic). To address this, the present eye-tracking study examined the time course of distractor suppression. Participants searched for and compared two targets to determine whether to make a response or withhold responding (“No-go” trials). The No-go trials allowed observation of post-decision suppression via eye movements. Response-critical target features either remained present for the whole trial (Experiment 1) or were removed halfway through (Experiment 2). In Experiment 1, distractors in the frequent region were substantially less likely to attract eye movements, including after inspection of both targets. However, in Experiment 2, the post-target distractor-region effect disappeared when the response-critical information was removed, indicating that suppression operates phasically and flexibly.

The proactive and reactive mechanisms of learned spatial suppression.

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

Tracking the Misallocation and Reallocation of Spatial Attention toward Auditory Stimuli.

Completely ignoring a salient distractor presented concurrently with a target is difficult, and sometimes attention is involuntarily attracted to the distractor's location (attentional capture). Employing the N2ac component as a marker of attention allocation toward sounds, in this study we investigate the spatiotemporal dynamics of auditory attention across two experiments. Human participants (male and female) performed an auditory search task, where the target was accompanied by a distractor in two-third of the trials. For a distractor more salient than the target (Experiment 1), we observe not only a distractor N2ac (indicating attentional capture) but the full chain of attentional dynamics implied by the notion of attentional capture, namely, (1) the distractor captures attention before the target is attended, (2) allocation of attention to the target is delayed by distractor presence, and (3) the target is attended after the distractor. Conversely, for a distractor less salient than the target (Experiment 2), although responses were delayed, no attentional capture was observed. Together, these findings reveal two types of spatial attentional dynamics in the auditory modality (distraction with and without attentional capture).

Object-based suppression in target search but not in distractor inhibition.

The present study investigated the effect of object representation on attentional priority regarding distractor inhibition and target search processes while the statistical regularities of singleton distractor location were biased. A color singleton distractor appeared more frequently at one of six stimulus locations, called the 'high-probability location,' to induce location-based suppression. Critically, three objects were presented, each of which paired two adjacent stimuli in a target display by adding background contours (Experiment 1) or using perceptual grouping (Experiments 2 and 3). The results revealed that attention capture by singleton distractors was hardly modulated by objects. In contrast, target selection was impeded at the location in the object containing the high-probability location compared to an equidistant location in a different object. This object-based suppression in target selection was evident when object-related features were parts of task-relevant features. These findings suggest that task-irrelevant objects modulate attentional suppression. Moreover, different features are engaged in determining attentional priority for distractor inhibition and target search processes.

Numerical study of the impact of osteotomies and distractor location in surgically assisted rapid palatal expansion for transverse maxillary deficiency

IntroductionThis paper employs finite element analysis to assess the biomechanical behavior of surgically assisted rapid palatal expansion (SARPE) with a bone-borne transpalatal distractor (TPD) by varying surgical parameters. Material and methodsNine models were constructed to scrutinize the effects of pterygomaxillary disjunction (PMD), lateral osteotomy positioning, and TPD placement on displacement profiles and Von Mises stresses. These models encompassed variations such as no, unilateral or bilateral PMD, asymmetrical lateral osteotomy, and five TPD locations. ResultsPerforming a PMD reduces posterior resistance to transverse expansion, resulting in 10–20 % stress reduction around the maxillofacial complex. No significant changes in horizontal tipping were observed post-PMD. The asymmetric lateral osteotomy model exhibited larger displacements on the side with a more superiorly positioned osteotomy. Reduced stresses were observed at the maxillary body and medial pterygoid plate (superiorly), while increased stresses were observed at the medial (inferiorly) and lateral pterygoid plates. More posterior TPD placement facilitated more parallel expansion thus less horizontal tipping, albeit with increased vertical tipping. DiscussionSARPE procedures (distractor and osteotomy positions) can be tailored based on desired outcomes. PMD reduces stress within the maxillofacial complex but doesn't significantly affect tipping. Higher lateral osteotomies lead to increased displacements, more posterior distractors to more parallel expansion.

Contextual cueing—Eye movements in rotated and recombined displays

Contextual cueing leads to improved efficiency in visual search resulting from the extraction of spatial regularities in repeated visual stimuli. Previous research has demonstrated the independent contributions of global configuration and spatial position to contextual cueing. The present study aimed to investigate whether learned spatial configuration or individual locations would elicit fixation patterns resembling those observed in the original displays. We found that search guidance based on either local or global spatial context, by combining distractor locations from two learned displays or rotating displays, kept not only search time facilitation intact, in agreement with previous studies, but also enabled search with less fixations and more direct scan paths to the target. Fixation distribution maps of recombined or rotated displays were more similar to the original displays than random new displays. However, for rotated displays this was only true when the rotation angle was taken into account. Overall, this shows an astonishingly flexible use of the oculomotor system for search in incompletely repeated displays.

Post-error adjustments occur in both reaching and grasping.

Post-error slowing (PES), the tendency to slow down a behavioral response after a previous error, has typically been investigated during simple cognitive tasks using response time as a measure of PES magnitude. More recently, PES was investigated during a single reach-to-grasp task to determine where post-error adjustments are employed in a more ecological setting. Kinematic analyses in the previous study detected PES during pre-movement planning and within the grasping component of movement execution. In the current study (N = 22), we increased the cognitive demands of a reach-to-grasp task by adding a choice between target and distractor locations to further explore PES, and other post-error adjustments, under different task conditions. We observed a significant main effect of task condition on overall reaction time (RT); however, it did not significantly impact PES or other post-error adjustments. Nonetheless, the results of this study suggest post-error adjustment is a flexible process that can be observed during pre-movement planning and within the onset and magnitude of the reaching component, as well as in the magnitudes of the grasping component. Considering the sum of the results in the context of existing literature, we conclude that the findings add support to a functional account of error reactivity, such that post-error adjustments are implemented intentionally to improve performance.

Steady-state Visual Evoked Potentials Reveal Dynamic (Re)allocation of Spatial Attention during Maintenance and Utilization of Visual Working Memory.

Visual working memory (VWM) allows storing goal-relevant information to guide future behavior. Prior work suggests that VWM is spatially organized and relies on spatial attention directed toward locations at which memory items were encoded, even if location is task-irrelevant. Importantly, attention often needs to be dynamically redistributed between locations, for example, in preparation for an upcoming probe. Very little is known about how attentional resources are distributed between multiple locations during a VWM task and even less about the dynamic changes governing such attentional shifts over time. This is largely due to the inability to use behavioral outcomes to reveal fast dynamic changes within trials. We here demonstrated that EEG steady-state visual evoked potentials (SSVEPs) successfully track the dynamic allocation of spatial attention during a VWM task. Participants were presented with to-be-memorized gratings and distractors at two distinct locations, tagged with flickering discs. This allowed us to dynamically track attention allocated to memory and distractor items via their coupling with space by quantifying the amplitude and coherence of SSVEP responses in the EEG signal to flickering stimuli at the former memory and distractor locations. SSVEP responses did not differ between memory and distractor locations during early maintenance. However, shortly before probe comparison, we observed a decrease in SSVEP coherence over distractor locations indicative of a reallocation of spatial attentional resources. RTs were shorter when preceded by stronger decreases in SSVEP coherence at distractor locations, likely reflecting attentional shifts from the distractor to the probe or memory location. We demonstrate that SSVEPs can inform about dynamic processes in VWM, even if location does not have to be reported by participants. This finding not only supports the notion of a spatially organized VWM but also reveals that SSVEPs betray a dynamic prioritization process of working memory items and locations over time that is directly predictive of memory performance.

Development and Validation of the Spatial Separation Sentence Test in Kannada.

This study aimed to develop and validate a modified version of the Speech in Noise Sentence Test in Kannada, which would be appropriate for testing the speech comprehension ability of children aged 8-12 years. A total of 120 sentences were chosen from 200 familiar sentences and split into four lists. Continuous discourse was used as a competition or distractor. Using MATLAB, the target stimulus was presented at 0-degree azimuth while the distractor's location varied (+90° and -90° azimuth). The test was programmed to dynamically adjust the signal-to-noise ratio (SNR) based on participants' responses. After initial validation, a pilot study was conducted with 60 typically hearing children aged 8 to 12 years. The SNR50 scores significantly improved when the distractor and target sentences were spatially separated across all groups. Age had a significant influence on the spatial separation scores. The test-retest reliability was excellent. The developed stimuli effectively measured spatial separation, and the normative and psychometric analyses demonstrated reliable outcomes.

Learned relevance of a distracting cue can influence feature interference errors

ABSTRACT Previous research has shown that attention can be guided via past experiences and learned regularities of target and/or distractor location. Here, we ask: could the learned relevance of a distracting cue affect our ability to suppress it and prevent feature interference errors? Participants reported the colour of a target item, while a salient distractor cue appeared on some trials. Critically, the experiment was split into two contexts, which differed based on whether the target and distracting cue could appear at the same location. We used a probabilistic mixture model to estimate feature report errors. We found a significant difference in swap rates (misreporting the colour at the salient distractor location instead of target colour) between the two contexts depending on the order they were experienced. These results suggest that the learned relevance of a distractor cue can affect how likely it is to capture attention and impact target feature perception.

Handling distractor interference in mixed and fixed search

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

Activated long-term memory and visual working memory during hybrid visual search: Effects on target memory search and distractor memory.

In hybrid visual search, observers must maintain multiple target templates and subsequently search for any one of those targets. If the number of potential target templates exceeds visual working memory (VWM) capacity, then the target templates are assumed to be maintained in activated long-term memory (aLTM). Observers must search the array for potential targets (visual search), as well as search through memory (target memory search). Increasing the target memory set size reduces accuracy, increases search response times (RT), and increases dwell time on distractors. However, the extent of observers' memory for distractors during hybrid search is largely unknown. In the current study, the impact of hybrid search on target memory search (measured by dwell time on distractors, false alarms, and misses) and distractor memory (measured by distractor revisits and recognition memory of recently viewed distractors) was measured. Specifically, we aimed to better understand how changes in behavior during hybrid search impacts distractor memory. Increased target memory set size led to an increase in search RTs, distractor dwell times, false alarms, and target identification misses. Increasing target memory set size increased revisits to distractors, suggesting impaired distractor location memory, but had no effect on a two-alternative forced-choice (2AFC) distractor recognition memory test presented during the search trial. The results from the current study suggest a lack of interference between memory stores maintaining target template representations (aLTM) and distractor information (VWM). Loading aLTM with more target templates does not impact VWM for distracting information.

Contextual uncertainty determines early attentional orienting in visual selection

ABSTRACT Our attention can be inadvertently captured by irrelevant or distracting stimuli. Past work has shown that knowledge about the search context in which targets and distractors occur, such as where distractors often occur, can greatly reduce attentional capture. In this study, we set out to show that uncertainty about this context (or contextual variability) is another critical determinant of attentional capture by physically salient distractors. Specifically, in three (preregistered) capture-probe experiments (n =288, n = 114, n = 114), we manipulated singleton distractor location and context uncertainty separately from set size. We found that rendering the distractor location less variable did not affect attentional capture. However, when contextual uncertainty was reduced, by keeping parts of the search display fixed across trials or by exposing participants to a restricted set of search configurations, attentional capture disappeared. Our findings support the notion that contextual uncertainty is a critical factor determining whether salient distractors capture attention.

Performance on a spatially selective auditory attention listening task for sources in the horizontal or coronal planes

Listeners can use spatially selective auditory attention (SSAA) to focus on one talker in a complex acoustic scene. SSAA has been primarily investigated with targets and distractors arrayed in the frontal horizontal plane. In this study we compared normally hearing human listeners' performance on static and dynamic SSAA tasks in a frontal target/distractor configuration to performance with sources arrayed in either the rear horizontal plane, the overhead coronal plane, or the “underhead” coronal plane, all of which provide similar binaural difference cues with which to differentiate target and distractor locations. To achieve the coronal plane configurations, the listener's head was tipped forward to align the normally vertical axis with the horizontal plane. In the SSAA task, listeners attempted to report a 4-digit sequence of spoken digits from the target location while ignoring two simultaneous equal-intensity sequences spoken by the same talker presented from flanking loudspeakers separated by ±22.5° from the target. Listeners either held their head still (static conditions) with the front (horizontal configurations) or top (coronal configurations) of the head oriented toward 0 azimuth, or were oscillated passively at ∼0.14 Hz with an amplitude of ±45 degrees about the vertical axis (dynamic conditions).

The effect of gaze information associated with the search items on contextual cueing effect.

Previous research on the mechanisms of contextual cueing effect has been inconsistent, with some researchers showing that the contextual benefit was derived from the attentional guidance whereas others argued that the former theory was not the source of contextual cueing effect. We brought the "stare-in-the-crowd" effect that used pictures of gaze with different orientations as stimuli into a traditional contextual cueing effect paradigm to investigate whether attentional guidance plays a part in this effect. We embedded the letters used in a traditional contextual cueing effect paradigm into the gaze pictures with direct and averted orientation. In Experiment 1, we found that there was a weak interaction between the contextual cueing effect and the "stare-in-the-crowd" effect. In Experiments 2 and 3, we found that the contextual cueing effect was influenced differently when the direct gaze was combined with the target or distractors. These results suggested that attentional guidance played an important role in the generation of a contextual cueing effect and the direct gaze had a special impact on visual search. To summarize the three findings, the direct gaze on target location facilitates the contextual cueing effect, and such an effect is even greater when we compared condition with the direct gaze on target location with condition with the direct gaze on distractor location (Experiments 2 and 3). Such an effect of gaze on a contextual cueing effect is manifested even when the effect of gaze ("stare-in-the-crowd" effect) was absent in the New configurations (search trials without learning).

Cue Predictability Modulates the Perceptual Load's Attentional Control on Threatening Facial Distractors

Background: According to the perceptual load theory, distractor processing is determined by the perceptual load. Alternatively, some explanations suggest that perceptual load and distractor salience may have opposing effects. Objectives: Although numerous studies have been conducted on the effect of distractor salience on attentional capture, even under conditions of high perceptual load, it is still unclear whether spatial cueing of the distractor interferes with the perceptual load. Methods: In two experiments, the effect of the predictability of distractor cueing on attentional capture due to threatening facial stimuli was studied using a modified flanker task. In experiment 2, unlike the first experiment, heterogeneous targets and distractors were used to mimic real-life experiences. Results: In experiment 1, the high perceptual load was associated with decreased distractor processing, whether the cueing was completely valid, invalid, or absent. However, the distractor processing between low and high perceptual loads was not different in ambiguous cueing. In the second experiment, contrary to the first experiment, no perceptual load effect was observed in the absence of spatial cueing. Conclusions: Even in displays with high perceptual load, some stimulus-driven features-inability to predict the distractor's location—can interfere with attentional control. Therefore, although the perceptual load is an influential factor in the selection, it clearly cannot be the only factor determining attentional control. Additionally, this study reveals that the effect of perceptual load on attentional control in everyday life should be further studied and questioned.

Suppression of a salient distractor protects the processing of target features.

We are often bombarded with salient stimuli that capture our attention and distract us from our current goals. Decades of research have shown the robust detrimental impacts of salient distractors on search performance and, of late, in leading to altered feature perception. These feature errors can be quite extreme, and thus, undesirable. In search tasks, salient distractors can be suppressed if they appear more frequently in one location, and this learned spatial suppression can lead to reductions in the cost of distraction as measured by reaction time slowing. Can learned spatial suppression also protect against visual feature errors? To investigate this question, participants were cued to report one of four briefly presented colored squares on a color wheel. On two-thirds of trials, a salient distractor appeared around one of the nontarget squares, appearing more frequently in one location over the course of the experiment. Participants' responses were fit to a model estimating performance parameters and compared across conditions. Our results showed that general performance (guessing and precision) improved when the salient distractor appeared in a likely location relative to elsewhere. Critically, feature swap errors (probability of misreporting the color at the salient distractor's location) were also significantly reduced when the distractor appeared in a likely location, suggesting that learned spatial suppression of a salient distractor helps protect the processing of target features. This study provides evidence that, in addition to helping us avoid salient distractors, suppression likely plays a larger role in helping to prevent distracting information from being encoded.