Spatial suppression due to statistical regularities is driven by distractor suppression not by target activation

2018 ◽  
Author(s):  
Michel Failing ◽  
Benchi Wang ◽  
Jan Theeuwes
Keyword(s):  
High Probability ◽  
Target Location ◽  
Target Selection ◽  
Visual Space ◽  
Alternative Interpretation ◽  
Distractor Location ◽  
Target Presentation ◽  
Statistical Regularities ◽  
Low Probability ◽  
Presentation Experiment

Where and what we attend to is not only determined by what we are currently looking for but also by what we have encountered in the past. Recent studies suggest that biasing the probability by which distractors appear at locations in visual space may lead to attentional suppression of high probability distractor locations which effectively reduces capture by a distractor but also impairs target selection at this location. However, in many of these studies introducing a high probability distractor location was tantamount to increasing the probability of the target appearing in any of the other locations (i.e. the low probability distractor locations). Here, we investigate an alternative interpretation of previous findings according to which attentional selection at high probability distractor locations is not suppressed. Instead, selection at low probability distractor locations is facilitated. In two visual search tasks, we found no evidence for this hypothesis: neither when there was only a bias in target presentation but no bias in distractor presentation (Experiment 1), nor when there was only a bias in distractor presentation but no bias in target presentation (Experiment 2). We conclude that recurrent presentation of a distractor in a specific location leads to attentional suppression of that location through a mechanism that is unaffected by any regularities regarding the target location.

scholarly journals Statistical regularities cause attentional suppression with target-matching distractors

2020 ◽  
Author(s):  
Dirk Kerzel ◽  
Stanislas Huynh Cong
Keyword(s):  
High Frequency ◽  
Target Location ◽  
Low Frequency ◽  
Target Display ◽  
Distractor Location ◽  
Target Feature ◽  
Statistical Regularities ◽  
Feature Based ◽  
The Impact ◽  
Target Matching

AbstractVisual search may be disrupted by the presentation of salient, but irrelevant stimuli. To reduce the impact of salient distractors, attention may suppress their processing below baseline level. While there are many studies on the attentional suppression of distractors with features distinct from the target (e.g., a color distractor with a shape target), there is little and inconsistent evidence for attentional suppression with distractors sharing the target feature. In this study, distractor and target were temporally separated in a cue–target paradigm, where the cue was shown briefly before the target display. With target-matching cues, RTs were shorter when the cue appeared at the target location (valid cues) compared with when it appeared at a nontarget location (invalid cues). To induce attentional suppression, we presented the cue more frequently at one out of four possible target positions. We found that invalid cues appearing at the high-frequency cue position produced less interference than invalid cues appearing at a low-frequency cue position. Crucially, target processing was also impaired at the high-frequency cue position, providing strong evidence for attentional suppression of the cued location. Overall, attentional suppression of the frequent distractor location could be established through feature-based attention, suggesting that feature-based attention may guide attentional suppression just as it guides attentional enhancement.

Spatial suppression due to statistical regularities in a visual detection task

2021 ◽  
Author(s):  
Dirk van Moorselaar ◽  
Jan Theeuwes
Keyword(s):  
Statistical Learning ◽  
Attentional Capture ◽  
High Probability ◽  
Visual Detection ◽  
Detection Task ◽  
Distractor Location ◽  
Specific Location ◽  
Statistical Regularities ◽  
Unique Shape ◽  
Singleton Target

AbstractIncreasing evidence demonstrates that observers can learn the likely location of salient singleton distractors during visual search. To date, the reduced attentional capture at high-probability distractor locations has typically been examined using so called compound search, in which by design a target is always present. Here, we explored whether statistical distractor learning can also be observed in a visual detection task, in which participants respond target present if the singleton target is present and respond target absent when the singleton target is absent. If so, this allows us to examine suppression of the location that is likely to contain a distractor both in the presence, but critically also in the absence, of a priority signal generated by the target singleton. In an online variant of the additional singleton paradigm, observers had to indicate whether a unique shape was present or absent, while ignoring a colored singleton, which appeared with a higher probability in one specific location. We show that attentional capture was reduced, but not absent, at high-probability distractor locations, irrespective of whether the display contained a target or not. By contrast, target processing at the high-probability distractor location was selectively impaired on distractor-present displays. Moreover, all suppressive effects were characterized by a gradient such that suppression scaled with the distance to the high-probability distractor location. We conclude that statistical distractor learning can be examined in visual detection tasks, and discuss the implications for attentional suppression due to statistical learning.

scholarly journals Involvement of the Dorsolateral Prefrontal Cortex of Monkeys in Visuospatial Target Selection

2003 ◽  
Vol 89 (1) ◽  
pp. 587-599 ◽  
Author(s):  
Michiyo Iba ◽  
Toshiyuki Sawaguchi
Keyword(s):  
Prefrontal Cortex ◽  
Visual Search ◽  
Dorsolateral Prefrontal Cortex ◽  
Target Location ◽  
Target Selection ◽  
Visual Space ◽  
Reversible Inactivation ◽  
Correct Performance ◽  
Dorsolateral Prefrontal ◽  
Target Locations

To examine the involvement of the dorsolateral prefrontal cortex (PFC) in visuospatial target selection, we induced local, reversible inactivation with muscimol at various sites in the dorsolateral PFC of two rhesus monkeys while they performed oculomotor visual search (OVS) and oculomotor detection (OD) tasks. The OVS task required the subject to select a target stimulus from among distractors and to make a saccade to the target location (target selection was required for correct performance), whereas the OD task only required a saccade to the target (target selection was not required for correct performance). The local injection of muscimol (5 μg, 1 μl) into the dorsolateral PFC induced a specific deficit in the OVS task but not in the OD task. The deficit in the OVS task was characterized by the disordering of saccades for some (mostly a few) particular target locations as well as by prolongation of the time required for the visual search in most cases. The target locations affected by muscimol were biased to the contralateral visual field. Further, the OVS task with “pop-out” and “non-pop-out” conditions was similarly impaired by muscimol injection. These results suggest that the dorsolateral PFC plays a role in target selection in visual space to guide goal-directed motor acts and particular sites are involved in target selection for a particular visuospatial coordinate. Further, this function of the dorsolateral PFC appears to involve both top-down (active) and bottom-up (passive) target-selection/selective attention processes to control interfering information (distractors).

scholarly journals Proactive distractor suppression elicited by statistical regularities in visual search

2021 ◽  
Author(s):  
Changrun Huang ◽  
Ana Vilotijević ◽  
Jan Theeuwes ◽  
Mieke Donk
Keyword(s):  
Visual Search ◽  
Statistical Learning ◽  
High Probability ◽  
Search Task ◽  
Reaction Times ◽  
Distractor Interference ◽  
Probe Task ◽  
Priority Map ◽  
Statistical Regularities ◽  
Low Probability

AbstractIrrelevant salient objects may capture our attention and interfere with visual search. Recently, it was shown that distraction by a salient object is reduced when it is presented more frequently at one location than at other locations. The present study investigates whether this reduced distractor interference is the result of proactive spatial suppression, implemented prior to display onset, or reactive suppression, occurring after attention has been directed to that location. Participants were asked to search for a shape singleton in the presence of an irrelevant salient color singleton which was presented more often at one location (the high-probability location) than at all other locations (the low-probability locations). On some trials, instead of the search task, participants performed a probe task, in which they had to detect the offset of a probe dot. The results of the search task replicated previous findings showing reduced distractor interference in trials in which the salient distractor was presented at the high-probability location as compared with the low-probability locations. The probe task showed that reaction times were longer for probes presented at the high-probability location than at the low-probability locations. These results indicate that through statistical learning the location that is likely to contain a distractor is suppressed proactively (i.e., prior to display onset). It suggests that statistical learning modulates the first feed-forward sweep of information processing by deprioritizing locations that are likely to contain a distractor in the spatial priority map.

Brain-Electrical Correlates of Negative Location Priming Under Sustained and Transient Attentional Context Conditions

2006 ◽  
Vol 20 (3) ◽  
pp. 160-169 ◽  
Author(s):  
Hannes Ruge ◽  
Ewald Naumann
Keyword(s):  
Sustained Attention ◽  
Target Location ◽  
Event Related Potentials ◽  
Distractor Location ◽  
Target Presentation ◽  
After Effects ◽  
Probe Target ◽  
Related Potentials ◽  
Physically Identical ◽  
Lateralization Effect

In the present study event-related potentials (ERPs) and event-related lateralizations (ERLs) were analyzed to investigate mechanisms of attentional inhibition engaged when a target stimulus has to be located within a simultaneous target-distractor display. The putative after-effects of inhibition were examined with a prime-probe technique by comparing a “DT” condition (the prime Distractor location becomes the probe Target location) with a control condition (the probe target appears at a previously empty position). The specific aim was to dissociate more “automatic” aspects from more “controlled” aspects associated with the inhibition of distractor locations. To do so, we compared physically identical prime-probe pairs in a sustained-attention context (same target throughout a block) and a transient-attention context (trial-by-trial target specification). Three early ERP/ERL components showed differential effects for DT compared to control: (1) the posterior N1 with a diminished amplitude contralateral to the visual half-field side of target presentation, (2) the N2pc with an enhanced amplitude contralateral to the visual half-field side of target presentation, and (3) the posteriorly distributed N2 with a nonlateralized enhancement for DT compared to control. These effects were differently affected by the context manipulation. While the N2pc effect was observed exclusively under sustained attention, the N1 lateralization effect and the N2 effect were not differentially modulated. The N1 lateralization effect seems consistent with an inhibition-of-return explanation. The N2pc and N2 effects are supposed to be reflecting different aspects of a biased-competition model of distractor inhibition.

scholarly journals Incomplete Suppression of Distractor-Related Activity in the Frontal Eye Field Results in Curved Saccades

2006 ◽  
Vol 96 (5) ◽  
pp. 2699-2711 ◽  
Author(s):  
Robert M. McPeek
Keyword(s):  
Target Location ◽  
Temporal Structure ◽  
Target Selection ◽  
Neural Correlates ◽  
Frontal Eye Field ◽  
Stimulation Site ◽  
Related Activity ◽  
Distractor Location ◽  
Significant Difference ◽  
Eye Field

Saccades in the presence of distractors show significant trajectory curvature. Based on previous work in the superior colliculus (SC), we speculated that curvature arises when a movement is initiated before competition between the target and distractor goals has been fully resolved. To test this hypothesis, we recorded frontal eye field (FEF) activity for curved and straight saccades in search. In contrast to the SC, activity in FEF is normally poorly correlated with saccade dynamics. However, the FEF, like the SC, is involved in target selection. Thus if curvature is caused by incomplete target selection, we expect to see its neural correlates in the FEF. We found that saccades that curve toward a distractor are accompanied by an increase in perisaccadic activity of FEF neurons coding the distractor location, and saccades that curve away are accompanied by a decrease in activity. In contrast, for FEF neurons coding the target location, there is no significant difference in activity between curved and straight saccades. To establish that the distractor-related activity is causally related to saccade curvature, we applied microstimulation to sites in the FEF before saccades to targets presented without distractors. The stimulation was subthreshold for evoking saccades and the temporal structure of the stimulation train resembled the activity recorded for curved saccades. The resulting movements curved toward the location coded by the stimulation site. These results support the idea that saccade curvature results from incomplete suppression of distractor-related activity during target selection.

Validation of a machine learned model to predict the diagnosis of myocardial infarction

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
D Doudesis ◽  
J Yang ◽  
A Tsanas ◽  
C Stables ◽  
A Shah ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Coronary Syndrome ◽  
Predictive Value ◽  
High Probability ◽  
Cardiovascular Death ◽  
Gradient Boosting ◽  
Funding Source ◽  
Coronary Syndrome ◽  
Low Probability ◽  
One Year

Abstract Introduction The myocardial-ischemic-injury-index (MI3) is a promising machine learned algorithm that predicts the likelihood of myocardial infarction in patients with suspected acute coronary syndrome. Whether this algorithm performs well in unselected patients or predicts recurrent events is unknown. Methods In an observational analysis from a multi-centre randomised trial, we included all patients with suspected acute coronary syndrome and serial high-sensitivity cardiac troponin I measurements without ST-segment elevation myocardial infarction. Using gradient boosting, MI3 incorporates age, sex, and two troponin measurements to compute a value (0–100) reflecting an individual's likelihood of myocardial infarction, and estimates the negative predictive value (NPV) and positive predictive value (PPV). Model performance for an index diagnosis of myocardial infarction, and for subsequent myocardial infarction or cardiovascular death at one year was determined using previously defined low- and high-probability thresholds (1.6 and 49.7, respectively). Results In total 20,761 of 48,282 (43%) patients (64±16 years, 46% women) were eligible of whom 3,278 (15.8%) had myocardial infarction. MI3 was well discriminated with an area under the receiver-operating-characteristic curve of 0.949 (95% confidence interval 0.946–0.952) identifying 12,983 (62.5%) patients as low-probability (sensitivity 99.3% [99.0–99.6%], NPV 99.8% [99.8–99.9%]), and 2,961 (14.3%) as high-probability (specificity 95.0% [94.7–95.3%], PPV 70.4% [69–71.9%]). At one year, subsequent myocardial infarction or cardiovascular death occurred more often in high-probability compared to low-probability patients (17.6% [520/2,961] versus 1.5% [197/12,983], P<0.001). Conclusions In unselected consecutive patients with suspected acute coronary syndrome, the MI3 algorithm accurately estimates the likelihood of myocardial infarction and predicts probability of subsequent adverse cardiovascular events. Performance of MI3 at example thresholds Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): Medical Research Council

scholarly journals Prediction of Patients with Acute Cholecystitis Requiring Emergent Cholecystectomy: A Simple Score

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Wael N. Yacoub ◽  
Mikael Petrosyan ◽  
Indu Sehgal ◽  
Yanling Ma ◽  
Parakrama Chandrasoma ◽  
...  
Keyword(s):  
Heart Rate ◽  
Logistic Regression ◽  
Acute Cholecystitis ◽  
High Probability ◽  
Acute Inflammation ◽  
Gallbladder Wall ◽  
Cutoff Score ◽  
Gangrenous Cholecystitis ◽  
Pathological Review ◽  
Low Probability

The objective was to develop a score, to stratify patients with acute cholecystitis into high, intermediate, or low probability of gangrenous cholecystitis. The probability of gangrenous cholecystitis (score) was derived from a logistic regression of a clinical and pathological review of 245 patients undergoing urgent cholecystectomy. Sixty-eight patients had gangrenous inflammation, 132 acute, and 45 no inflammation. The score comprised of: age > 45 years (1 point), heart rate > 90 beats/min (1 point), male (2 points), Leucocytosis > 13,000/mm3(1.5 points), and ultrasound gallbladder wall thickness>4.5 mm (1 point). The prevalence of gangrenous cholecystitis was 13% in the low-probability (0–2 points), 33% in the intermediate-probability (2–4.5 points), and 87% in the high probability category (>4.5 points). A cutoff score of 2 identified 31 (69%) patients with no acute inflammation (PPV 90%). This scoring system can prioritize patients for emergent cholecystectomy based on their expected pathology.

Frequency of enforcement is more important than the severity of punishment in reducing violation behaviors

2021 ◽  
Vol 118 (42) ◽  
pp. e2108507118
Author(s):  
Kinneret Teodorescu ◽  
Ori Plonsky ◽  
Shahar Ayal ◽  
Rachel Barkan
Keyword(s):  
High Probability ◽  
Real Life ◽  
Expected Value ◽  
Relative Importance ◽  
Decisions From Experience ◽  
High Severity ◽  
Low Probability ◽  
Violation Rate ◽  
Severity Of Punishment ◽  
Enforcement Policies

External enforcement policies aimed to reduce violations differ on two key components: the probability of inspection and the severity of the punishment. Different lines of research offer different insights regarding the relative importance of each component. In four studies, students and Prolific crowdsourcing participants (Ntotal = 816) repeatedly faced temptations to commit violations under two enforcement policies. Controlling for expected value, we found that a policy combining a high probability of inspection with a low severity of fines (HILS) was more effective than an economically equivalent policy that combined a low probability of inspection with a high severity of fines (LIHS). The advantage of prioritizing inspection frequency over punishment severity (HILS over LIHS) was greater for participants who, in the absence of enforcement, started out with a higher violation rate. Consistent with studies of decisions from experience, frequent enforcement with small fines was more effective than rare severe fines even when we announced the severity of the fine in advance to boost deterrence. In addition, in line with the phenomenon of underweighting of rare events, the effect was stronger when the probability of inspection was rarer (as in most real-life inspection probabilities) and was eliminated under moderate inspection probabilities. We thus recommend that policymakers looking to effectively reduce recurring violations among noncriminal populations should consider increasing inspection rates rather than punishment severity.

Portable Ventilation/Perfusion Scanning is Useful for Evaluating Clinically Significant Pulmonary Embolism in the ICU Despite Abnormal Chest Radiography

2018 ◽  
Vol 35 (10) ◽  
pp. 1032-1038 ◽  
Author(s):  
Aaron S. Weinberg ◽  
William Chang ◽  
Grace Ih ◽  
Alan Waxman ◽  
Victor F. Tapson
Keyword(s):  
Pulmonary Embolism ◽  
Chest Radiograph ◽  
High Probability ◽  
Hemodynamic Instability ◽  
X Rays ◽  
X Ray ◽  
Abnormal Chest ◽  
Chest X Ray ◽  
Low Probability ◽  
Clinically Significant

Objective: Computed tomography angiography is limited in the intensive care unit (ICU) due to renal insufficiency, hemodynamic instability, and difficulty transporting unstable patients. A portable ventilation/perfusion (V/Q) scan can be used. However, it is commonly believed that an abnormal chest radiograph can result in a nondiagnostic scan. In this retrospective study, we demonstrate that portable V/Q scans can be helpful in ruling in or out clinically significant pulmonary embolism (PE) despite an abnormal chest x-ray in the ICU. Design: Two physicians conducted chart reviews and original V/Q reports. A staff radiologist, with 40 years of experience, rated chest x-ray abnormalities using predetermined criteria. Setting: The study was conducted in the ICU. Patients: The first 100 consecutive patients with suspected PE who underwent a portable V/Q scan. Interventions: Those with a portable V/Q scan. Results: A normal baseline chest radiograph was found in only 6% of patients. Fifty-three percent had moderate, 24% had severe, and 10% had very-severe radiographic abnormalities. Despite the abnormal x-rays, 88% of the V/Q scans were low probability for a PE despite an average abnormal radiograph rating of moderate. A high-probability V/Q for PE was diagnosed in 3% of the population despite chest x-ray ratings of moderate to severe. Six patients had their empiric anticoagulation discontinued after obtaining the results of the V/Q scan, and no anticoagulation was started for PE after a low-probability V/Q scan. Conclusion: Despite the large percentage of moderate-to-severe x-ray abnormalities, PE can still be diagnosed (high-probability scan) in the ICU with a portable V/Q scan. Although low-probability scans do not rule out acute PE, it appeared less likely that any patient with a low-probability V/Q scan had severe hypoxemia or hemodynamic instability due to a significant PE, which was useful to clinicians and allowed them to either stop or not start anticoagulation.

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