scholarly journals Spatial attention follows category-based attention during naturalistic visual search: evidence from MEG decoding

2018 ◽  
Author(s):  
Elisa Battistoni ◽  
Daniel Kaiser ◽  
Clayton Hickey ◽  
Marius V. Peelen
Keyword(s):  
Visual Search ◽  
Time Course ◽  
Target Location ◽  
Daily Life ◽  
Stimulus Onset ◽  
Target Presence ◽  
Object Categories ◽  
Search Experiment ◽  
Category Search ◽  
High Level

AbstractIn daily life, attention is often directed to high-level object attributes, such as when we look out for cars before crossing a road. Previous work used MEG decoding to investigate the influence of such category-based attention on the time course of object category representations. Attended object categories were more strongly represented than unattended categories from 180 ms after scene onset. In the present study, we used a similar approach to determine when, relative to this category-level modulation, attention is spatially focused on the target. Participants completed two tasks. In the first, they detected cars and people at varying locations in photographs of real-world scenes. In the second, they detected a cross that appeared at salient locations in an array of lines. Multivariate classifiers were trained on data of the artificial salience experiment and tested on data of the naturalistic visual search experiment. Results showed that the location of both target and distracter objects could be accurately decoded shortly after scene onset (50 ms). However, the emergence of spatial attentional selection - reflected in better decoding of target location than distracter location - emerged only later in time (240 ms). Target presence itself (irrespective of location and category) could be decoded from 180 ms after stimulus onset. Combined with earlier work, these results indicate that naturalistic category search operates through an initial spatially-global modulation of category processing that then guides attention to the location of the target.

scholarly journals The Rapid Extraction of Gist—Early Neural Correlates of High-level Visual Processing

2012 ◽  
Vol 24 (2) ◽  
pp. 521-529 ◽  
Author(s):  
Frank Oppermann ◽  
Uwe Hassler ◽  
Jörg D. Jescheniak ◽  
Thomas Gruber
Keyword(s):  
Visual Processing ◽  
Time Course ◽  
Occipital Cortex ◽  
Stimulus Onset ◽  
Gamma Band ◽  
Oscillatory Activity ◽  
Rapid Extraction ◽  
The Right ◽  
High Level ◽  
Individual Objects

The human cognitive system is highly efficient in extracting information from our visual environment. This efficiency is based on acquired knowledge that guides our attention toward relevant events and promotes the recognition of individual objects as they appear in visual scenes. The experience-based representation of such knowledge contains not only information about the individual objects but also about relations between them, such as the typical context in which individual objects co-occur. The present EEG study aimed at exploring the availability of such relational knowledge in the time course of visual scene processing, using oscillatory evoked gamma-band responses as a neural correlate for a currently activated cortical stimulus representation. Participants decided whether two simultaneously presented objects were conceptually coherent (e.g., mouse–cheese) or not (e.g., crown–mushroom). We obtained increased evoked gamma-band responses for coherent scenes compared with incoherent scenes beginning as early as 70 msec after stimulus onset within a distributed cortical network, including the right temporal, the right frontal, and the bilateral occipital cortex. This finding provides empirical evidence for the functional importance of evoked oscillatory activity in high-level vision beyond the visual cortex and, thus, gives new insights into the functional relevance of neuronal interactions. It also indicates the very early availability of experience-based knowledge that might be regarded as a fundamental mechanism for the rapid extraction of the gist of a scene.

scholarly journals Visual search for object categories is predicted by the representational architecture of high-level visual cortex

2017 ◽  
Vol 117 (1) ◽  
pp. 388-402 ◽  
Author(s):  
Michael A. Cohen ◽  
George A. Alvarez ◽  
Ken Nakayama ◽  
Talia Konkle
Keyword(s):  
Visual Cortex ◽  
Visual Search ◽  
Visual System ◽  
Visual Processing ◽  
Search Task ◽  
Visual Search Task ◽  
Visual Object ◽  
Neural Responses ◽  
Object Categories ◽  
High Level

Visual search is a ubiquitous visual behavior, and efficient search is essential for survival. Different cognitive models have explained the speed and accuracy of search based either on the dynamics of attention or on similarity of item representations. Here, we examined the extent to which performance on a visual search task can be predicted from the stable representational architecture of the visual system, independent of attentional dynamics. Participants performed a visual search task with 28 conditions reflecting different pairs of categories (e.g., searching for a face among cars, body among hammers, etc.). The time it took participants to find the target item varied as a function of category combination. In a separate group of participants, we measured the neural responses to these object categories when items were presented in isolation. Using representational similarity analysis, we then examined whether the similarity of neural responses across different subdivisions of the visual system had the requisite structure needed to predict visual search performance. Overall, we found strong brain/behavior correlations across most of the higher-level visual system, including both the ventral and dorsal pathways when considering both macroscale sectors as well as smaller mesoscale regions. These results suggest that visual search for real-world object categories is well predicted by the stable, task-independent architecture of the visual system. NEW & NOTEWORTHY Here, we ask which neural regions have neural response patterns that correlate with behavioral performance in a visual processing task. We found that the representational structure across all of high-level visual cortex has the requisite structure to predict behavior. Furthermore, when directly comparing different neural regions, we found that they all had highly similar category-level representational structures. These results point to a ubiquitous and uniform representational structure in high-level visual cortex underlying visual object processing.

Attention Effects on Form Discrimination at Different Eccentricities

1989 ◽  
Vol 41 (4) ◽  
pp. 719-746 ◽  
Author(s):  
MaryLou Cheal ◽  
Don Lyon
Keyword(s):  
Time Course ◽  
Target Location ◽  
Short Soas ◽  
Stimulus Onset ◽  
Attention Shifting ◽  
Form Discrimination ◽  
Discrimination Accuracy ◽  
Target Stimulus Onset Asynchrony ◽  
Time Course Of Attention ◽  
Onset Asynchrony

Considerable disagreement exists in the visual attention literature about how attention is allocated over the visual field. One frequently expressed metaphor is that attention moves like a spotlight, and in some variants it is assumed that attention takes longer to shift to targets further from fixation. In order to test this metaphor, five experiments were conducted in which target location was precued and form discrimination accuracy was assessed. By varying the interval between the precue and the target (stimulus onset asynchrony, SOA), a time course of attention effects was obtained for targets at 2°, 6°, and 10° eccentricity. In the first three experiments, precueing effects were found, but there were no differences in performance as a function of eccentricity for very short SOAs, with either a peripheral cue or a foveal arrow cue. For long SOAs, however, performance was better for targets that were closer to fixation. In Experiments 4 (peripheral cue) and 5 (foveal cue), the targets were scaled to make them equally discriminable at all eccentricities. Again precueing effects were found, but there were no differences in accuracy as a function of eccentricity for most SOAs. These results suggest that attention shifting is not analogous to a constant-velocity moving spotlight.

scholarly journals Searching for Something Familiar or Novel: Top–Down Attentional Selection of Specific Items or Object Categories

2013 ◽  
Vol 25 (5) ◽  
pp. 719-729 ◽  
Author(s):  
Rachel Wu ◽  
Gaia Scerif ◽  
Richard N. Aslin ◽  
Tim J. Smith ◽  
Rebecca Nako ◽  
...  
Keyword(s):  
Visual Search ◽  
Attentional Control ◽  
Target Selection ◽  
Top Down ◽  
Prime Stimulus ◽  
Attentional Guidance ◽  
Object Categories ◽  
Item Level ◽  
Category Search ◽  
Selection Of

Visual search is often guided by top–down attentional templates that specify target-defining features. But search can also occur at the level of object categories. We measured the N2pc component, a marker of attentional target selection, in two visual search experiments where targets were defined either categorically (e.g., any letter) or at the item level (e.g., the letter C) by a prime stimulus. In both experiments, an N2pc was elicited during category search, in both familiar and novel contexts (Experiment 1) and with symbolic primes (Experiment 2), indicating that, even when targets are only defined at the category level, they are selected at early sensory-perceptual stages. However, the N2pc emerged earlier and was larger during item-based search compared with category-based search, demonstrating the superiority of attentional guidance by item-specific templates. We discuss the implications of these findings for attentional control and category learning.

Irrelevant Singletons in Visual Search Do Not Capture Attention but Can Produce Nonspatial Filtering Costs

2011 ◽  
Vol 23 (3) ◽  
pp. 645-660 ◽  
Author(s):  
Agnieszka Wykowska ◽  
Anna Schubö
Keyword(s):  
Visual Search ◽  
Visual Processing ◽  
Time Course ◽  
Target Location ◽  
Gain Control ◽  
Top Down ◽  
Preattentive Processing ◽  
Singleton Distractor ◽  
And Performance ◽  
Singleton Condition

It is not clear how salient distractors affect visual processing. The debate concerning the issue of whether irrelevant salient items capture spatial attention [e.g., Theeuwes, J., Atchley, P., & Kramer, A. F. On the time course of top–down and bottom–up control of visual attention. In S. Monsell & J. Driver (Eds.), Attention and performance XVIII: Control of cognitive performance (pp. 105–124). Cambridge, MA: MIT Press, 2000] or produce only nonspatial interference in the form of, for example, filtering costs [Folk, Ch. L., & Remington, R. Top–down modulation of preattentive processing: Testing the recovery account of contingent capture. Visual Cognition, 14, 445–465, 2006] has not yet been settled. The present ERP study examined deployment of attention in visual search displays that contained an additional irrelevant singleton. Display-locked N2pc showed that attention was allocated to the target and not to the irrelevant singleton. However, the onset of the N2pc to the target was delayed when the irrelevant singleton was presented in the opposite hemifield relative to the same hemifield. Thus, although attention was successfully focused on the target, the irrelevant singleton produced some interference resulting in a delayed allocation of attention to the target. A subsequent probe discrimination task allowed for locking ERPs to probe onsets and investigating the dynamics of sensory gain control for probes appearing at relevant (target) or irrelevant (singleton distractor) positions. Probe-locked P1 showed sensory gain for probes positioned at the target location but no such effect for irrelevant singletons in the additional singleton condition. Taken together, the present data support the claim that irrelevant singletons do not capture attention. If they produce any interference, it is rather due to nonspatial filtering costs.

scholarly journals Visual search behavior and performance in luggage screening: effects of time pressure, automation aid, and target expectancy

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Tobias Rieger ◽  
Lydia Heilmann ◽  
Dietrich Manzey
Keyword(s):  
Visual Search ◽  
Target Location ◽  
Time Pressure ◽  
Response Times ◽  
Search Behavior ◽  
High Time ◽  
Luggage Screening ◽  
Negative Effect ◽  
And Performance ◽  
Automated Support

AbstractVisual inspection of luggage using X-ray technology at airports is a time-sensitive task that is often supported by automated systems to increase performance and reduce workload. The present study evaluated how time pressure and automation support influence visual search behavior and performance in a simulated luggage screening task. Moreover, we also investigated how target expectancy (i.e., targets appearing in a target-often location or not) influenced performance and visual search behavior. We used a paradigm where participants used the mouse to uncover a portion of the screen which allowed us to track how much of the stimulus participants uncovered prior to their decision. Participants were randomly assigned to either a high (5-s time per trial) or a low (10-s time per trial) time-pressure condition. In half of the trials, participants were supported by an automated diagnostic aid (85% reliability) in deciding whether a threat item was present. Moreover, within each half, in target-present trials, targets appeared in a predictable location (i.e., 70% of targets appeared in the same quadrant of the image) to investigate effects of target expectancy. The results revealed better detection performance with low time pressure and faster response times with high time pressure. There was an overall negative effect of automation support because the automation was only moderately reliable. Participants also uncovered a smaller amount of the stimulus under high time pressure in target-absent trials. Target expectancy of target location improved accuracy, speed, and the amount of uncovered space needed for the search.Significance Statement Luggage screening is a safety–critical real-world visual search task which often has to be done under time pressure. The present research found that time pressure compromises performance and increases the risk to miss critical items even with automation support. Moreover, even highly reliable automated support may not improve performance if it does not exceed the manual capabilities of the human screener. Lastly, the present research also showed that heuristic search strategies (e.g., areas where targets appear more often) seem to guide attention also in luggage screening.

scholarly journals Complete heart block in cardiac sarcoidosis reversed by corticosteroid therapy: time course of resolution

2021 ◽  
Vol 14 (3) ◽  
pp. e240834
Author(s):  
Anna Tomdio ◽  
Huzaefah Syed ◽  
Kenneth Ellenbogen ◽  
Jordana Kron
Keyword(s):  
Heart Block ◽  
Time Course ◽  
Cardiac Sarcoidosis ◽  
Complete Heart Block ◽  
Positron Emission ◽  
Av Conduction ◽  
Magnetic Resonance Imaging Mri ◽  
High Level ◽  
Active Inflammation ◽  
Lateral Walls

A 53-year-old man was admitted for recurrent syncope and found to have complete heart block (CHB). Cardiac magnetic resonance imaging MRI) showed extensive patchy late gadolinium enhancement in the apical and lateral walls, consistent with cardiac sarcoidosis (CS) but no scar in the septum. A fluorodeoxyglucose (FDG)–positron emission tomography showed FDG uptake in the septum and basal lateral walls. Imaging suggested active inflammation in the septum affecting atrioventricular (AV) conduction but no irreversible fibrosis. Diagnosis of isolated CS requires a high level of suspicion and multidisciplinary teamwork involving heart failure specialists, electrophysiologists and rheumatologists. After specialist and patient discussion, treatment of the disease was initiated with prednisone 40 mg daily, 11 months after presenting with CHB. Three weeks later, ECG with pacing inhibited showed second-degree AV block Mobitz type II and 4 weeks later, AV conduction recovery. This highlights the importance of immediate therapy in reversing AV conduction abnormalities in CS.

Temporal Dynamics of Shape Analysis in Macaque Visual Area V2

2004 ◽  
Vol 92 (5) ◽  
pp. 3030-3042 ◽  
Author(s):  
Jay Hegdé ◽  
David C. Van Essen
Keyword(s):  
Cortical Neurons ◽  
Time Course ◽  
Temporal Dynamics ◽  
Visual Stimulation ◽  
Signal To Noise Ratio ◽  
Stimulus Onset ◽  
Visual Area ◽  
Response Modulation ◽  
Population Response ◽  
Area V2

The firing rate of visual cortical neurons typically changes substantially during a sustained visual stimulus. To assess whether, and to what extent, the information about shape conveyed by neurons in visual area V2 changes over the course of the response, we recorded the responses of V2 neurons in awake, fixating monkeys while presenting a diverse set of static shape stimuli within the classical receptive field. We analyzed the time course of various measures of responsiveness and stimulus-related response modulation at the level of individual cells and of the population. For a majority of V2 cells, the response modulation was maximal during the initial transient response (40–80 ms after stimulus onset). During the same period, the population response was relatively correlated, in that V2 cells tended to respond similarly to specific subsets of stimuli. Over the ensuing 80–100 ms, the signal-to-noise ratio of individual cells generally declined, but to a lesser degree than the evoked-response rate during the corresponding time bins, and the response profiles became decorrelated for many individual cells. Concomitantly, the population response became substantially decorrelated. Our results indicate that the information about stimulus shape evolves dynamically and relatively rapidly in V2 during static visual stimulation in ways that may contribute to form discrimination.

Neural structures involved in visual search guidance by reward-enhanced contextual cueing of the target location

NeuroImage ◽  
2016 ◽  
Vol 124 ◽  
pp. 887-897 ◽  
Author(s):  
Stefan Pollmann ◽  
Jana Eštočinová ◽  
Susanne Sommer ◽  
Leonardo Chelazzi ◽  
Wolf Zinke
Keyword(s):  
Visual Search ◽  
Target Location ◽  
Contextual Cueing ◽  
Search Guidance

Converging Evidence That Neural Plasticity Underlies Transcranial Direct-Current Stimulation

2021 ◽  
Vol 33 (1) ◽  
pp. 146-157
Author(s):  
Chong Zhao ◽  
Geoffrey F. Woodman
Keyword(s):  
Visual Search ◽  
Direct Current ◽  
Neural Plasticity ◽  
Transcranial Direct Current Stimulation ◽  
Time Course ◽  
Memory Task ◽  
Long Term Memory ◽  
Visual Stream ◽  
Direct Current Stimulation ◽  
The Brain

It is not definitely known how direct-current stimulation causes its long-lasting effects. Here, we tested the hypothesis that the long time course of transcranial direct-current stimulation (tDCS) is because of the electrical field increasing the plasticity of the brain tissue. If this is the case, then we should see tDCS effects when humans need to encode information into long-term memory, but not at other times. We tested this hypothesis by delivering tDCS to the ventral visual stream of human participants during different tasks (i.e., recognition memory vs. visual search) and at different times during a memory task. We found that tDCS improved memory encoding, and the neural correlates thereof, but not retrieval. We also found that tDCS did not change the efficiency of information processing during visual search for a certain target object, a task that does not require the formation of new connections in the brain but instead relies on attention and object recognition mechanisms. Thus, our findings support the hypothesis that direct-current stimulation modulates brain activity by changing the underlying plasticity of the tissue.

Sign in / Sign up

Export Citation Format

Share Document