scholarly journals Oscillatory Mechanisms of Preparing for Visual Distraction

2019 ◽  
Vol 31 (12) ◽  
pp. 1873-1894 ◽  
Author(s):  
Ingmar E. J. de Vries ◽  
Ece Savran ◽  
Joram van Driel ◽  
Christian N. L. Olivers
Keyword(s):  
Sensory Processing ◽  
Search Display ◽  
Delay Period ◽  
Alpha Power ◽  
Visual Distraction ◽  
Search Tasks ◽  
Active Attention ◽  
Target Templates ◽  
Suppression Mechanism ◽  
Oscillatory Mechanisms

Evidence shows that observers preactivate a target representation in preparation of a visual selection task. In this study, we addressed the question if and how preparing to ignore an anticipated distractor differs from preparing for an anticipated target. We measured EEG while participants memorized a laterally presented color, which was cued to be either a target or a distractor in two subsequent visual search tasks. Decoding the location of items in the search display from EOG channels revealed that, initially, the anticipated distractor attracted attention and could only be ignored later during the trial. This suggests that distractors could not be suppressed in advance but were represented in an active, attention-guiding format. Consistent with this, lateralized posterior alpha power did not dissociate between target and distractor templates during the delay periods, suggesting similar encoding and maintenance. However, distractor preparation did lead to relatively enhanced nonlateralized posterior alpha power, which appeared to gate sensory processing at search display onset to prevent attentional capture in general. Finally, anticipating distractors also led to enhanced midfrontal theta power during the delay period, a signal that was predictive of how strongly both target and distractor were represented in the search display. Together, our results speak against a distractor-specific advance inhibitory template, thus contrary to the preactivation of specific target templates. Rather, we demonstrate a general selection suppression mechanism, which serves to prevent initial involuntary capture by anticipated distracting input.

Visual Search: How Do We Find What We Are Looking For?

2020 ◽  
Vol 6 (1) ◽  
pp. 539-562 ◽  
Author(s):  
Jeremy M. Wolfe
Keyword(s):  
Visual Search ◽  
Long Term Memory ◽  
Simple Shape ◽  
Term Memory ◽  
Parallel Processes ◽  
Search Tasks ◽  
Street Sign ◽  
Complex Scenes ◽  
Target Templates

In visual search tasks, observers look for targets among distractors. In the lab, this often takes the form of multiple searches for a simple shape that may or may not be present among other items scattered at random on a computer screen (e.g., Find a red T among other letters that are either black or red.). In the real world, observers may search for multiple classes of target in complex scenes that occur only once (e.g., As I emerge from the subway, can I find lunch, my friend, and a street sign in the scene before me?). This article reviews work on how search is guided intelligently. I ask how serial and parallel processes collaborate in visual search, describe the distinction between search templates in working memory and target templates in long-term memory, and consider how searches are terminated.

Increases in Alpha Oscillatory Power Reflect an Active Retinotopic Mechanism for Distracter Suppression During Sustained Visuospatial Attention

2006 ◽  
Vol 95 (6) ◽  
pp. 3844-3851 ◽  
Author(s):  
Simon P. Kelly ◽  
Edmund C. Lalor ◽  
Richard B. Reilly ◽  
John J. Foxe
Keyword(s):  
Visual Cues ◽  
Letter Sequence ◽  
Alpha Power ◽  
Visual Spatial Attention ◽  
Visual Spatial ◽  
Random Letter ◽  
Oscillatory Power ◽  
Suppression Mechanism ◽  
Left And Right ◽  
S Period

Human electrophysiological (EEG) studies have demonstrated the involvement of alpha band (8- to 14-Hz) oscillations in the anticipatory biasing of attention. In the context of visual spatial attention within bilateral stimulus arrays, alpha has exhibited greater amplitude over parietooccipital cortex contralateral to the hemifield required to be ignored, relative to that measured when the same hemifield is to be attended. Whether this differential effect arises solely from alpha desynchronization (decreases) over the “attending” hemisphere, from synchronization (increases) over the “ignoring” hemisphere, or both, has not been fully resolved. This is because of the confounding effect of externally evoked desynchronization that occurs involuntarily in response to visual cues. Here, bilateral flickering stimuli were presented simultaneously and continuously over entire trial blocks, such that externally evoked alpha desynchronization is equated in precue baseline and postcue intervals. Equivalent random letter sequences were superimposed on the left and right flicker stimuli. Subjects were required to count the presentations of the target letter “X” at the cued hemifield over an 8-s period and ignore the sequence in the opposite hemifield. The data showed significant increases in alpha power over the ignoring hemisphere relative to the precue baseline, observable for both cue directions. A strong attentional bias necessitated by the subjective difficulty in gating the distracting letter sequence is reflected in a large effect size of 2.1 (η2 = 0.82), measured from the attention × hemisphere interaction. This strongly suggests that alpha synchronization reflects an active attentional suppression mechanism, rather than a passive one reflecting “idling” circuits.

scholarly journals The development of foraging organization

2021 ◽  
Author(s):  
Inga María Ólafsdóttir ◽  
Steinunn Gestsdóttir ◽  
Arni Kristjansson
Keyword(s):  
Path Length ◽  
Optimal Path ◽  
Age Groups ◽  
Search Display ◽  
Target Type ◽  
Search Tasks ◽  
Visual Orienting ◽  
Single Target ◽  
Feature Based ◽  
Promising Avenue

In foraging tasks multiple targets must be found within a single display. The targets can be of one or more types, typically surrounded by numerous distractors. Visual attention has traditionally been studied with single target search tasks but adding more targets to the search display results in several additional measures of interest, such as how attention is oriented to different features and locations over time. We measured foraging among five age groups: Children in grades 1, 4, 7, and 10, as well as adults, using both simple feature foraging tasks and more challenging conjunction foraging tasks, with two target types per task. We assessed participants’ foraging organization, or systematicity when selecting all the targets within the foraging display, on four measures: Intertarget distance, number of intersections, best-r, and the percentage above optimal path length (PAO). We found that foraging organization increases with age, in both simple feature-based foraging and more complex foraging for targets defined by feature conjunctions, and that feature foraging was more organized than conjunction foraging. Separate analyses for different target types indicated that children’s, and to some extent adults’, conjunction foraging consisted of two relatively organized foraging paths through the display where one target type is exhaustively selected before the other target type is selected. Lastly, we found that the development of foraging organization is closely related to the development of other foraging measures. Our results suggest that measuring foraging organization is a promising avenue for further research into the development of visual orienting.

Human Cortical-Evoked Fields during Detection, Localisation, and Identification of ‘Pop-out’ Targets

Perception ◽  
1998 ◽  
Vol 27 (2) ◽  
pp. 215-224 ◽  
Author(s):  
Jukka Saarinen ◽  
Simo Vanni ◽  
Riitta Hari
Keyword(s):  
Target Identification ◽  
Maximum Amplitude ◽  
Cortical Activity ◽  
Search Display ◽  
Detection Task ◽  
Temporal Region ◽  
Temporal Area ◽  
Search Tasks ◽  
Passive Viewing ◽  
The Right

We investigated human cortical activity during four ‘effortless-pop-out’ visual search tasks with the use of magnetoencephalography. The search display, which was identical across all the tasks, consisted of vertical line segments, one of which was rotated abruptly 45° clockwise or counterclockwise. In the passive-viewing task the observers gave no response to the search display. In the target-detection task they responded to the onset of the target motion irrespective of its location and direction. In the target-localisation task the observers reported whether the line rotation appeared above or below the fixation point while ignoring the direction of the rotation. In contrast, in the target-identification task they indicated the direction of the line rotation, and the location of the rotation in the array was irrelevant. Cortical activity was recorded with a whole-scalp magnetometer while the observers were performing each task. In addition to the expected activation of the occipital and somatomotor cortical regions, two other active cortical areas were consistently identified in both hemispheres: one in the occipito-temporal area, probably corresponding to the motion-specific V5 complex, and another in the parieto-temporal region. The activation of the right occipito-temporal source depended on the task. The maximum amplitude was smallest for the passive viewing, increased for the detection task, and was largest for the localisation and identification.

scholarly journals Impoverished Inhibitory Control Exacerbates Multisensory Impairments in Older Fallers

2021 ◽  
Vol 13 ◽  
Author(s):  
Alexandra N. Scurry ◽  
Zachary Lovelady ◽  
Daniela M. Lemus ◽  
Fang Jiang
Keyword(s):  
Older Adults ◽  
Inhibitory Control ◽  
Sensory Processing ◽  
Natural Aging ◽  
Gamma Activity ◽  
Oscillatory Activity ◽  
Alpha Power ◽  
Impaired Performance ◽  
Perceptual Performance ◽  
Illusory Percept

Impaired temporal perception of multisensory cues is a common phenomenon observed in older adults that can lead to unreliable percepts of the external world. For instance, the sound induced flash illusion (SIFI) can induce an illusory percept of a second flash by presenting a beep close in time to an initial flash-beep pair. Older adults that have enhanced susceptibility to a fall demonstrate significantly stronger illusion percepts during the SIFI task compared to those older adults without any history of falling. We hypothesize that a global inhibitory deficit may be driving the impairments across both postural stability and multisensory function in older adults with a fall history (FH). We investigated oscillatory activity and perceptual performance during the SIFI task, to understand how active sensory processing, measured by gamma (30–80 Hz) power, was regulated by alpha activity (8–13 Hz), oscillations that reflect inhibitory control. Compared to young adults (YA), the FH and non-faller (NF) groups demonstrated enhanced susceptibility to the SIFI. Further, the FH group had significantly greater illusion strength compared to the NF group. The FH group also showed significantly impaired performance relative to YA during congruent trials (2 flash-beep pairs resulting in veridical perception of 2 flashes). In illusion compared to non-illusion trials, the NF group demonstrated reduced alpha power (or diminished inhibitory control). Relative to YA and NF, the FH group showed reduced phase-amplitude coupling between alpha and gamma activity in non-illusion trials. This loss of inhibitory capacity over sensory processing in FH compared to NF suggests a more severe change than that consequent of natural aging.

scholarly journals Theta Oscillations Index Frontal Decision-Making and Mediate Reciprocal Frontal–Parietal Interactions in Willed Attention

2018 ◽  
Vol 29 (7) ◽  
pp. 2832-2843 ◽  
Author(s):  
Abhijit Rajan ◽  
Scott N Siegel ◽  
Yuelu Liu ◽  
Jesse Bengson ◽  
George R Mangun ◽  
...  
Keyword(s):  
Decision Making ◽  
Attentional Control ◽  
Decision Processes ◽  
Theta Oscillations ◽  
Alpha Power ◽  
Prior Work ◽  
Theta Band ◽  
Voluntary Attention ◽  
External Cues ◽  
Oscillatory Mechanisms

Abstract Attention can be attracted reflexively by sensory signals, biased by learning or reward, or focused voluntarily based on momentary goals. When voluntary attention is focused by purely internal decision processes (will), rather than instructions via external cues, we call this “willed attention.” In prior work, we reported ERP and fMRI correlates of willed spatial attention in trial-by-trial cuing tasks. Here we further investigated the oscillatory mechanisms of willed attention by contrasting the event-related EEG spectrogram between instructional and choice cues. Two experiments were conducted at 2 different sites using the same visuospatial attention paradigm. Consistent between the 2 experiments, we found increases in frontal theta power (starting at ~500 ms post cue) for willed attention relative to instructed attention. This frontal theta increase was accompanied by increased frontal–parietal theta-band coherence and bidirectional Granger causality. Additionally, the onset of attention-related posterior alpha power lateralization was delayed in willed attention relative to instructed attention, and the amount of delay was related to the timing of frontal theta increase. These results, replicated across 2 experiments, suggest that theta oscillations are the neuronal signals indexing decision-making in the frontal cortex, and mediating reciprocal communications between the frontal executive and parietal attentional control regions during willed attention.

scholarly journals Deciding on Optical Illusions: Reduced Alpha Power in Body Dysmorphic Disorder

2022 ◽  
Author(s):  
Anastasios E. Giannopoulos ◽  
Ioanna Zioga ◽  
Konstantinos Kontoangelos ◽  
Panos Papageorgiou ◽  
Fotini Kapsali ◽  
...  
Keyword(s):  
Decision Making ◽  
Task Performance ◽  
Body Dysmorphic Disorder ◽  
Quantitative Eeg ◽  
Delay Period ◽  
Alpha Power ◽  
Optical Illusions ◽  
Degree Of Confidence ◽  
Task Irrelevant ◽  
The Brain

Background: Body dysmorphic disorder (BDD) is a psychiatric disorder characterized by excessive preoccupation with imagined defects in appearance. Optical illusions induce illusory effects that distort the presented stimulus thus leading to ambiguous percepts. Using electroencephalography (EEG), we investigated whether BDD is related to differentiated perception during illusory percepts. Methods: 18 BDD patients and 18 controls were presented with 39 optical illusions together with a statement testing whether or not they perceived the illusion. After a delay period, they were prompted to answer whether the statement is right/wrong and their degree of confidence for their answer. We investigated differences of BDD on task performance and self-reported confidence and analysed the brain oscillations during decision-making using nonparametric cluster statistics. Results: Behaviorally, the BDD group exhibited reduced confidence when responding incorrectly, potentially attributed to higher levels of doubt. Electrophysiologically, the BDD group showed significantly reduced alpha power at mid-central scalp areas, suggesting impaired allocation of attention. Interestingly, the lower the alpha power of the identified cluster, the higher the BDD severity, as assessed by BDD psychometrics. Conclusions: Results evidenced that alpha power during illusory processing might serve as a quantitative EEG biomarker of BDD, potentially associated with reduced inhibition of task-irrelevant areas.

scholarly journals Unattended but actively stored: EEG dynamics reveal a dissociation between selective attention and storage in working memory

2018 ◽  
Author(s):  
E. Gunseli ◽  
J. Fahrenfort ◽  
D. van Moorselaar ◽  
K. Daoultzis ◽  
M. Meeter ◽  
...  
Keyword(s):  
Working Memory ◽  
Selective Attention ◽  
High Reliability ◽  
Information Loss ◽  
Delay Period ◽  
Alpha Power ◽  
Relative Importance ◽  
Eeg Signals ◽  
Contralateral Delay Activity ◽  
And Storage

AbstractSelective attention plays a prominent role in prioritizing information in working memory (WM), improving performance for attended representations. However, it remains unclear what the consequences of selection are for the maintenance of unattended WM representations, and whether this results in information loss. Here we tested the hypothesis that within WM, selectively attending to an item and the decision to stop storing other items involve independent mechanisms. We recorded EEG while participants performed a WM recall task in which the item most likely to be tested was cued retrospectively. By manipulating retro-cue reliability (i.e. the ratio of valid to invalid cue trials) we varied the incentive to retain uncued items. Contralateral alpha power suppression, a proxy for attention, indicated that, initially, the cued item was attended equally following high and low reliability cues, but attention was sustained throughout the delay period only after high reliability cues. Furthermore, contralateral delay activity (CDA), a proxy for storage, indicated that non-cued items were dropped sooner from WM after highly reliability cues than after cues with low reliability. These results show that attention and storage in WM are distinct processes that can behave differently depending on the relative importance of WM representations, as expressed in dissociable EEG signals.

scholarly journals Binding language: Structuring sentences through precisely timed oscillatory mechanisms

2017 ◽  
Author(s):  
Katrien Segaert ◽  
Ali Mazaheri ◽  
Peter Hagoort
Keyword(s):  
Target Word ◽  
Cognitive Processes ◽  
Alpha Power ◽  
Frequency Bands ◽  
Beta Power ◽  
Neural Processes ◽  
Data Driven Approach ◽  
Oscillatory Mechanisms ◽  
Beta Frequency ◽  
Syntactic Binding

AbstractSyntactic binding refers to combining words into larger structures. Using EEG, we investigated the neural processes involved in syntactic binding. Participants were auditorily presented two-word sentences (i.e. a pronoun and pseudoverb such as ‘she dotches’, for which syntactic binding can take place) and wordlists (i.e. two pseudoverbs such as ‘pob dotches’, for which no binding can occur). Comparing these two conditions, we targeted syntactic binding while minimizing contributions of semantic binding and of other cognitive processes such as working memory. We found a converging pattern of results using two distinct analysis approaches: one approach using frequency bands as defined in previous literature, and one data-driven approach in which we looked at the entire range of frequencies between 3-30 Hz without the constraints of pre-defined frequency bands. In the syntactic binding (relative to the wordlist) condition, a power increase was observed in the alpha and beta frequency range shortly preceding the presentation of the target word that requires binding, which was maximal over frontal-central electrodes. Our interpretation is that these signatures reflect that language comprehenders expect the need for binding to occur. Following the presentation of the target word in a syntactic binding context (relative to the wordlist condition), an increase in alpha power maximal over a left lateralized cluster of frontal-temporal electrodes was observed. We suggest that this alpha increase relates to syntactic binding taking place. Taken together, our findings suggest that increases in alpha and beta power are reflections of distinct the neural processes underlying syntactic binding.

scholarly journals Preparatory Template Activation during Search for Alternating Targets

2020 ◽  
Vol 32 (8) ◽  
pp. 1525-1535
Author(s):  
Anna Grubert ◽  
Martin Eimer
Keyword(s):  
Executive Control ◽  
Attentional Control ◽  
Time Course ◽  
Search Display ◽  
Target Color ◽  
Target Template ◽  
Target Templates ◽  
Irrelevant Color ◽  
Task Irrelevant ◽  
Time Point

Visual search is guided by representations of target-defining features (attentional templates). We tracked the time course of template activation processes during the preparation for search in a task where the identity of color-defined search targets switched across successive trials (ABAB). Task-irrelevant color probes that matched either the upcoming relevant target color or the previous now-irrelevant target color were presented every 200 msec during the interval between search displays. N2pc components (markers of attentional capture) were measured for both types of probes at each time point. A reliable probe N2pc indicates that the corresponding color template is active at the time when the probe appears. N2pcs of equal size emerged from 1000 msec before search display onset for both relevant-color and irrelevant-color probes, demonstrating that both color templates were activated concurrently. Evidence for color-selective attentional control was found only immediately before the arrival of the search display, where N2pcs were larger for relevant-color probes. These results reveal important limitations in the executive control of search preparation in tasks where two targets alternate across trials. Although the identity of the upcoming target is fully predictable, both task-relevant and task-irrelevant target templates are coactivated. Knowledge about target identity selectively biases these template activation processes in a temporally discrete fashion, guided by temporal expectations about when the target template will become relevant.

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