scholarly journals Modeling the Effects of Perceptual Load: Saliency, Competitive Interactions, and Top-Down Biases

2016 ◽  
Vol 7 ◽  
Author(s):  
Kleanthis Neokleous ◽  
Andria Shimi ◽  
Marios N. Avraamides
Keyword(s):  
Perceptual Load ◽  
Competitive Interactions ◽  
Top Down

scholarly journals Perceptual-Load-Induced Selection as a Result of Local Competitive Interactions in Visual Cortex

2008 ◽  
Vol 19 (10) ◽  
pp. 1045-1050 ◽  
Author(s):  
Ana Torralbo ◽  
Diane M. Beck
Keyword(s):  
Visual Cortex ◽  
Perceptual Load ◽  
A Priori ◽  
Visual Fields ◽  
Competitive Interactions ◽  
Spatial Interactions ◽  
Distractor Processing ◽  
Per Se ◽  
Definition Of ◽  
Perceptual Capacity

A growing literature suggests that the degree to which distracting information can be ignored depends on the perceptual load of the task, or the extent to which the task exhausts perceptual capacity. However, there is currently no a priori definition of what constitutes high or low perceptual load. We propose that interactions among cells in visual cortex that represent nearby stimuli determine the perceptual load of a task, and that manipulations designed to modulate these competitive spatial interactions should modulate distractor processing. We found that either spatially separating the task-relevant items in a display or placing the target and nontargets in different visual fields increased interference from a distractor that was to be ignored. These data are consistent with the idea that the ability to ignore such distracting information results in part from the need to actively resolve competitive interactions in visual cortex, and is not the consequence of an exhausted capacity per se.

scholarly journals Visual attention mediated by biased competition in extrastriate visual cortex

1998 ◽  
Vol 353 (1373) ◽  
pp. 1245-1255 ◽  
Author(s):  
Robert Desimone
Keyword(s):  
Visual Field ◽  
Visual Attention ◽  
Spatial Location ◽  
Competitive Interactions ◽  
Extrastriate Cortex ◽  
Neuronal Responses ◽  
Top Down ◽  
Biased Competition ◽  
Enhancing Effect ◽  
Neuronal Systems

According to conventional neurobiological accounts of visual attention, attention serves to enhance extrastriate neuronal responses to a stimulus at one spatial location in the visual field. However, recent results from recordings in extrastriate cortex of monkeys suggest that any enhancing effect of attention is best understood in the context of competitive interactions among neurons representing all of the stimuli present in the visual field. These interactions can be biased in favour of behaviourally relevant stimuli as a result of many different processes, both spatial and non–spatial, and both bottom–up and top–down. The resolution of this competition results in the suppression of the neuronal representations of behaviourally irrelevant stimuli in extrastriate cortex. A main source of top–down influence may derive from neuronal systems underlying working memory.

scholarly journals Top-down effects of semantic knowledge in visual search are modulated by cognitive but not perceptual load

2008 ◽  
Vol 70 (8) ◽  
pp. 1444-1458 ◽  
Author(s):  
E. BELKE ◽  
G. W. HUMPHREYS ◽  
D. G. WATSON ◽  
A. S. MEYER ◽  
A. L. TELLING
Keyword(s):  
Visual Search ◽  
Perceptual Load ◽  
Semantic Knowledge ◽  
Top Down

Top-Down Processing and Visual Reorientation Illusions in a Virtual Reality Environment

2004 ◽  
Vol 63 (3) ◽  
pp. 143-149 ◽  
Author(s):  
Fred W. Mast ◽  
Charles M. Oman
Keyword(s):  
Virtual Reality ◽  
Visual Processing ◽  
Line Length ◽  
Perceptual Cues ◽  
Virtual Reality Environment ◽  
Top Down ◽  
Test Conditions ◽  
The Subject ◽  
Processing Mechanisms

The role of top-down processing on the horizontal-vertical line length illusion was examined by means of an ambiguous room with dual visual verticals. In one of the test conditions, the subjects were cued to one of the two verticals and were instructed to cognitively reassign the apparent vertical to the cued orientation. When they have mentally adjusted their perception, two lines in a plus sign configuration appeared and the subjects had to evaluate which line was longer. The results showed that the line length appeared longer when it was aligned with the direction of the vertical currently perceived by the subject. This study provides a demonstration that top-down processing influences lower level visual processing mechanisms. In another test condition, the subjects had all perceptual cues available and the influence was even stronger.

Functional Anatomy of Intensity Aspects of Attention

2003 ◽  
Vol 14 (3) ◽  
pp. 181-190 ◽  
Author(s):  
Walter Sturm
Keyword(s):  
Right Hemisphere ◽  
Functional Anatomy ◽  
Fmri Data ◽  
Functional Networks ◽  
Top Down ◽  
Stimulus Modality ◽  
Spatial Orienting ◽  
Phasic Alertness ◽  
Co Activation ◽  
Attention System

Abstract: Behavioral and PET/fMRI-data are presented to delineate the functional networks subserving alertness, sustained attention, and vigilance as different aspects of attention intensity. The data suggest that a mostly right-hemisphere frontal, parietal, thalamic, and brainstem network plays an important role in the regulation of attention intensity, irrespective of stimulus modality. Under conditions of phasic alertness there is less right frontal activation reflecting a diminished need for top-down regulation with phasic extrinsic stimulation. Furthermore, a high overlap between the functional networks for alerting and spatial orienting of attention is demonstrated. These findings support the hypothesis of a co-activation of the posterior attention system involved in spatial orienting by the anterior alerting network. Possible implications of these findings for the therapy of neglect are proposed.

Auswirkungen eines Aufmerksamkeitstrainings auf die aphasische Symptomatik bei Schlaganfallpatienten

2011 ◽  
Vol 22 (1) ◽  
pp. 21-32 ◽  
Author(s):  
Julia Graf ◽  
Hartwig Kulke ◽  
Christa Sous-Kulke ◽  
Wilfried Schupp ◽  
Stefan Lautenbacher
Keyword(s):  
Top Down

Aufmerksamkeit kann als Kontrollsystem neuronaler Aktivität verstanden werden, welches Neuroplastizität top-down modulieren hilft. Bisher wurde selten versucht, durch deren gezielte Förderung Funktionswiederherstellungen nach Hirnschädigung zu begünstigen. In vorliegender Studie wurde dies am Beispiel der Aphasie erprobt. 15 Schlaganfallpatienten erhielten ein dreiwöchiges Training der selektiven Aufmerksamkeit mit den PC-Programmen CogniPlus und „Konzentration“ bei fünf Sitzungen pro Woche zusätzlich zur Standardtherapie, 13 weitere bildeten eine Kontrollgruppe ohne Aufmerksamkeitstraining. Zur Effektivitätskontrolle dienten zwei Versionen des Untertests Go/Nogo (Testbatterie zur Aufmerksamkeitsprüfung) und die Kurze Aphasieprüfung. Nach dem Training manifestierte sich zwischen den Untersuchungsgruppen kein Unterschied in Aufmerksamkeits- und Sprachfunktionen; das zusätzliche Aufmerksamkeitstraining war also wirkungslos. Allerdings zeigten Patienten mit deutlichen Aufmerksamkeitsverbesserungen tendenziell weniger Aphasie-Symptome, was die Hypothese aufmerksamkeitsvermittelter Plastizitätsmodulation nach Hirnschädigung partiell stützt.

Aufmerksamkeitswechsel und Konzentration: Von den Funktionen zum Mechanismus

2001 ◽  
Vol 209 (1) ◽  
pp. 34-53 ◽  
Author(s):  
Rainer Bösel
Keyword(s):  
Top Down ◽  
Eeg Alpha

Zusammenfassung. Aufmerksamkeit wird sowohl als Selektivität in der bewußter Verarbeitung oder auch als selektive neuronale Aktivierung verstanden. Die neuronalen Strukturen, die Objektdiskrimination ermöglichen, erlauben eine Interaktion von datengetriebenen und endogenen top-down Prozessen, die zu einer selektiven Bereitstellung von Verarbeitungs-Ressourcen führen. Zielgerichtetes Verhalten erfordert manchmal einen Wechsel in der Ressourcen-Bereitstellung und eine Konzentration von mentaler Aktivität. Aufmerksamkeitswechsel kann als ein zweiphasiger Prozeß verstanden werden, der aus einer breiten Mobilisierung von Gedächtnis-Ressourcen besteht (angezeigt durch EEG-Theta), gefolgt von einer re-organisierenden Einengung neuronaler Aktivität (angezeigt durch langsames EEG-Alpha). Dieser Beitrag unterstützt die Annahme, daß die Analyse des gekoppelten Wechselspiels aus Mobilisierung und Konzentration in bestimmten Teilen der posterioren und anterioren Rindenregionen ein Schlüssel für das Verständnis von Aufmerksamkeitswechsel sein könnte.

Psychology and Culture: Top Down Versus Bottom Up?

PsycCRITIQUES ◽  
2005 ◽  
Vol 50 (19) ◽  
Author(s):  
Michael Cole
Keyword(s):  
Top Down ◽  
Bottom Up
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