scholarly journals Electrophysiological correlates of active suppression and attentional selection in preview visual search

2018 ◽  
Vol 120 ◽  
pp. 75-85
Author(s):  
Nick Berggren ◽  
Martin Eimer
Keyword(s):  
Visual Search ◽  
Attentional Selection ◽  
Active Suppression

scholarly journals Why the item will remain the unit of attentional selection in visual search

2017 ◽  
Vol 40 ◽  
Author(s):  
Martin Eimer
Keyword(s):  
Visual Search ◽  
Parallel Architecture ◽  
Attentional Selection ◽  
Attentional Biases ◽  
Unit Of Selection ◽  
Critical Unit

AbstractHulleman & Olivers (H&O) reject item-based serial models of visual search, and they suggest that items are processed equally and globally during each fixation period. However, neuroscientific studies have shown that attentional biases can emerge in parallel but in a spatially selective item-based fashion. Even within a parallel architecture for visual search, the item remains the critical unit of selection.

An EEG study of the combined effects of top-down and bottom-up attentional selection under varying task difficulty

2021 ◽  
Author(s):  
Einat Rashal ◽  
Mehdi Senoussi ◽  
Elisa Santandrea ◽  
Suliann Ben Hamed ◽  
Emiliano Macaluso ◽  
...  
Keyword(s):  
Visual Search ◽  
Attentional Control ◽  
Task Difficulty ◽  
Target Selection ◽  
Attentional Selection ◽  
Combined Effects ◽  
Top Down ◽  
Bottom Up ◽  
Search Tasks

This work reports an investigation of the effect of combined top-down and bottom-up attentional control sources, using known attention-related EEG components that are thought to reflect target selection (N2pc) and distractor suppression (PD), in easy and difficult visual search tasks.

scholarly journals Dynamics of Feature-based Attentional Selection during Color–Shape Conjunction Search

2018 ◽  
Vol 30 (12) ◽  
pp. 1773-1787 ◽  
Author(s):  
Jeongmi Lee ◽  
Carly J. Leonard ◽  
Steven J. Luck ◽  
Joy J. Geng
Keyword(s):  
Sensory Neurons ◽  
Search Task ◽  
Attentional Selection ◽  
Conjunction Search ◽  
Attentional Processing ◽  
Active Suppression ◽  
Target Shape ◽  
Feature Based

Feature-based attentional selection is accomplished by increasing the gain of sensory neurons encoding target-relevant features while decreasing that of other features. But how do these mechanisms work when targets and distractors share features? We investigated this in a simplified color–shape conjunction search task using ERP components (N2pc, PD, and SPCN) that index lateralized attentional processing. In Experiment 1, we manipulated the presence and frequency of color distractors while holding shape distractors constant. We tested the hypothesis that the color distractor would capture attention, requiring active suppression such that processing of the target can continue. Consistent with this hypothesis, we found that color distractors consistently captured attention, as indexed by a significant N2pc, but were reactively suppressed (indexed by PD). Interestingly, when the color distractor was present, target processing was sustained (indexed by SPCN), suggesting that the dynamics of attentional competition involved distractor suppression interlinked with sustained target processing. In Experiment 2, we examined the contribution of shape to the dynamics of attentional competition under similar conditions. In contrast to color distractors, shape distractors did not reliably capture attention, even when the color distractor was very frequent and attending to target shape would be beneficial. Together, these results suggest that target-colored objects are prioritized during color–shape conjunction search, and the ability to select the target is delayed while target-colored distractors are actively suppressed.

scholarly journals Contribution of FEF to attentional periodicity during visual search: a TMS study

2018 ◽  
Author(s):  
Laura Dugué ◽  
Alexy Asaf Beck ◽  
Philippe Marque ◽  
Rufin VanRullen
Keyword(s):  
Feature Extraction ◽  
Visual Search ◽  
Search Task ◽  
Target Recognition ◽  
Higher Order ◽  
Attentional Selection ◽  
Two Stage ◽  
Theta Frequency ◽  
Stage Process ◽  
High Level

AbstractVisual search, looking for a target embedded among distractors, has long been used to study attention. Current theories postulate a two-stage process in which early visual areas perform feature extraction, while higher-order regions perform attentional selection. Such a model implies iterative communication between low- and high-level regions to sequentially select candidate targets in the array, focus attention on these elements, and eventually permit target recognition. This leads to two predictions: (1) high-level, attentional regions and (2) early visual regions should both be iteratively (periodically) involved during the search. Here, we used Transcranial Magnetic Stimulation (TMS) applied over the Frontal-Eye Field (FEF), known to be involved in attentional selection, at various delays while observers performed a difficult, attentional search task. We observed a periodic pattern of interference at 7 Hz (theta) suggesting that the FEF is periodically involved during this difficult search task. We further compared this result with two previous studies (Dugué et al., 2011; 2015a) in which a similar TMS procedure was applied over the early visual cortex (V1) while observers performed the same task. This analysis revealed, for both studies, the same pattern of interference, i.e. V1 is periodically involved during this difficult search task, at the theta frequency. Together, these converging findings confirm our predictions that difficult search is supported by the periodic involvement of both low- and high-level regions, at the theta frequency.Significant statementAttention models postulate a two-stage process during visual search in which early visual regions perform feature extraction, while higher-order regions perform attentional selection, these two levels iteratively (periodically) communicating until target recognition. Using TMS, we tested whether there is a causal link between both attentional and early visual regions, and attentional search performance. We showed that a difficult, attentional search is supported by the periodic involvement of both V1 and the FEF, at the theta frequency (∼6-7 Hz). This finding support the idea that visual search tasks are processed by a hierarchical system involving periodic, iterative connections between low- and high-level regions allowing successful attentional exploration.

scholarly journals The Attentional Template is Shifted and Asymmetrically Sharpened by Distractor Context

2018 ◽  
Author(s):  
Xinger Yu ◽  
Joy Geng
Keyword(s):  
Visual Search ◽  
Attentional Selection ◽  
Long Term Memory ◽  
Search Performance ◽  
Term Memory ◽  
Target Template ◽  
Colored Target

Theories of attention hypothesize the existence of an “attentional template” that contains target features in working or long-term memory. It is often assumed that the template contents are veridical, but recent studies have found that this is not true when the distractor set is linearly separable from the target (e.g., all distractors are “yellower” than an orange colored target). In such cases, the target representation in memory shifts away from distractor features (Navalpakkam & Itti, 2007) and develop a sharper boundary with distractors (Geng, DiQuattro & Helm, 2017). These changes in the target template are presumed to increase the target-to-distractor psychological distinctiveness and lead to better attentional selection, but it remains unclear what characteristics of the distractor context produce shifting vs. sharpening. Here, we test the hypothesis that the template representation shifts whenever the distractor set (i.e., all of the distractors) is linearly separable from the target, but that asymmetrical sharpening only occurs when linearly separable distractors are highly target-similar. Our results were consistent, suggesting that template shifting and asymmetrical sharpening are two mechanisms that increase the representational distinctiveness of targets from expected distractors and improve visual search performance.

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