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 Trial History Effects in the Ventral Attentional Network

2014 ◽  
Vol 26 (12) ◽  
pp. 2789-2797 ◽  
Author(s):  
Paige E. Scalf ◽  
JeeWon Ahn ◽  
Diane M. Beck ◽  
Alejandro Lleras
Keyword(s):  
Visual Search ◽  
Quantitative Analysis ◽  
Visual System ◽  
Task Performance ◽  
Attentional Biases ◽  
Top Down ◽  
History Effects ◽  
Attentional Network ◽  
Trial History ◽  
Stimulus Environment

The ventral attentional network (VAN) is thought to drive “stimulus driven attention” [e.g., Asplund, C. L., Todd, J. J., Snyder, A. P., & Marois, R. A central role for the lateral prefrontal cortex in goal-directed and stimulus-driven attention. Nature Neuroscience, 13, 507–512, 2010; Shulman, G. L., McAvoy, M. P., Cowan, M. C., Astafiev, S. V., Tansy, A. P., D' Avossa, G., et al. Quantitative analysis of attention and detection signals during visual search. Journal of Neurophysiology, 90, 3384–3397, 2003]; in other words, it instantiates within the current stimulus environment the top–down attentional biases maintained by the dorsal attention network [e.g., Kincade, J. M., Abrams, R. A., Astafiev, S. V., Shulman, G. L., & Corbetta, M. An event-related functional magnetic resonance imaging study of voluntary and stimulus-driven orienting of attention. The Journal of Neuroscience: The Official Journal of the Society for Neuroscience, 25, 4593–4604, 2005]. Previous work has shown that the dorsal attentional network is sensitive to trial history, such that it is challenged by changes in task goals and facilitated by repetition thereof [e.g., Kristjánsson, A., Vuilleumier, P., Schwartz, S., Macaluso, E., & Driver, J. Neural basis for priming of pop-out during visual search revealed with fMRI. Cerebral Cortex, 17, 1612–1624, 2007]. Here, we investigate whether the VAN also preserves information across trials such that it is challenged when previously rejected stimuli become task relevant. We used fMRI to investigate the sensitivity of the ventral attentional system to prior history effects as measured by the distractor preview effect. This behavioral phenomenon reflects a bias against stimuli that have historically not supported task performance. We found regions traditionally considered to be part of the VAN (right middle frontal gyrus, inferior frontal gyrus and right supramarginal gyrus) [Shulman, G. L., McAvoy, M. P., Cowan, M. C., Astafiev, S. V., Tansy, A. P., D' Avossa, G., et al. Quantitative analysis of attention and detection signals during visual search. Journal of Neurophysiology, 90, 3384–3397, 2003] to be more active when task-relevant stimuli had not supported task performance in a previous trial than when they had. Investigations of the ventral visual system suggest that this effect is more reliably driven by trial history preserved within the VAN than that preserved within the visual system per se. We conclude that VAN maintains its interactions with top–down stimulus biases and bottom–up stimulation across time, allowing previous experience with the stimulus environment to influence attentional biases under current circumstances.

Item-based selection is in good shape in visual compound search: A view from electrophysiology

2017 ◽  
Vol 40 ◽  
Author(s):  
Thomas Töllner ◽  
Dragan Rangelov
Keyword(s):  
Visual Search ◽  
Target Identification ◽  
Search Behaviour ◽  
Single Item ◽  
Good Shape ◽  
Unit Of Selection

AbstractWe argue that although the framework put forward by Hulleman & Olivers (H&O) can successfully explain much of visual search behaviour, it appears limited to tasks without precise target identification demands. In particular, we contend that the unit of selection may be larger than a single item in standard detection tasks, whereas the unit may mandatorily be item-based in compound tasks.

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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