Evidence that global processing does not limit thresholds for RF shape discrimination

Potentially relevant for those of us that use radial frequency patterns as stimuli: Discrimination thresholds are driven by local rather than global processing.

 

 

Feed: Journal of Vision current issue
Posted on: dinsdag 8 maart 2011 15:18
Author: Mullen, K. T., Beaudot, W. H. A., Ivanov, I. V.
Subject: Evidence that global processing does not limit thresholds for RF shape discrimination

 

In studies of shape processing, a crucial distinction is made between the global stages, which integrate across features to define shape, and earlier stages that encode individual components. We investigate whether shape discrimination thresholds for radial frequency (RF) patterns are limited at this global stage or whether the information in individual components supports threshold. We use achromatic and chromatic (L/M- and S-cone opponent) radial frequency (RF) patterns of different contour thicknesses (0.75–6 cpd). First, we show using sections of an RF4 that shape discrimination thresholds are invariant with cycle number from 1 to the complete pattern. Performance for a single cycle displayed alone is as good as for the whole RF, indicating that information within a single RF cycle is sufficient to support the whole shape discrimination threshold, arguing against an influence of global processing. Second, we find similar thresholds for the discrimination of RF patterns and modulated line stimuli, also arguing against global effects. Third, we calculate a metric for the intrinsic orientation variation in a stimulus cycle at threshold and show that this potentially accounts for the improvement in shape and line discrimination thresholds with modulation frequency from RF1 to RF6. Higher threshold discrimination for chromatic compared to achromatic patterns may reflect the poorer orientation discrimination of color vision, rather than a deficit for global processing. We propose that the global stages of shape processing are not revealed at threshold but are enabled only for well-defined shapes at suprathreshold modulations.

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Increased Stroop interference with better second-language reading skill

 

 

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Increased Stroop interference with better second-language reading skill

via : Articles recently published in by Op de Beeck, Hans on 2/26/11

 

 

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Visual cognition

Feed: ScienceDirect Publication: Vision Research
Posted on: woensdag 16 februari 2011 6:42
Author: ScienceDirect Publication: Vision Research
Subject: Visual cognition

 

Publication year: 2011 Source: Vision Research, In Press, Accepted Manuscript, Available online 15 February 2011 Patrick, Cavanagh Visual cognition, high-level vision, mid-level vision and top-down processing all refer to decision-based scene analyses that combine prior knowledge with retinal input to generate representations. The label "visual cognition" is little used at present, but research and experiments on mid- and high-level, inference-based vision have flourished, becoming in the 21st century a significant, if often understated part, of current vision research. How does visual cognition work? What are its moving parts? This paper reviews the origins and architecture of visual cognition and briefly describes some work in the areas of routines, attention, surfaces, objects, and events (motion, causality, and agency)....

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Mechanisms of Percept–Percept and Image–Percept Integration in Vision: Behav...

 

 

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Mechanisms of Percept–Percept and Image–Percept Integration in Vision: Behavioral and Electrophysiological Evidence

via ScienceDirect Publication: Journal of Experimental Psychology: Human Perception and Performance on 2/15/11

Publication year: 2011
Source: Journal of Experimental Psychology: Human Perception and Performance, Volume 37, Issue 1, February 2011, Pages 1-11
Silvia, Dalvit , Martin, Eimer
Previous research has shown that the detection of a visual target can be guided not only by the temporal integration of two percepts, but also by integrating a percept and an image held in working memory. Behavioral and event-related brain potential (ERP) measures were obtained in a target detection task that required temporal integration of 2 successively presented stimuli in the left or right hemifield. Task performance was good when both displays followed each other immediately (percept–percept integration) and when displays were separated by a 300- or 900-ms interval (image–percept integration), but was poor with intermediate interstimulus intervals. An enhanced...

 

 

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Motion Psychophysics: 1985-2010

 

 

Feed: ScienceDirect Publication: Vision Research
Posted on: dinsdag 15 februari 2011 6:38
Author: ScienceDirect Publication: Vision Research
Subject: Motion Psychophysics: 1985-2010

 

Publication year: 2011 Source: Vision Research, In Press, Accepted Manuscript, Available online 13 February 2011 David, Burr , Peter, Thompson This review traces progress made in the field of visual motion research from 1985 through to 2010. While it is certainly not exhaustive, it attempts to cover most of the major achievements during that period, and speculate on where the field is heading.

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Grasping the non-conscious: Preserved grip scaling to unseen objects for immediate but not delayed grasping following a unilateral lesion to primary visual cortex

 

 

Feed: ScienceDirect Publication: Vision Research
Posted on: dinsdag 15 februari 2011 6:38
Author: ScienceDirect Publication: Vision Research
Subject: Grasping the non-conscious: Preserved grip scaling to unseen objects for immediate but not delayed grasping following a unilateral lesion to primary visual cortex

 

Publication year: 2011 Source: Vision Research, In Press, Accepted Manuscript, Available online 13 February 2011 Robert L., Whitwell , Christopher L., Striemer , David A., Nicolle , Melvyn A., Goodale Patients with damage to primary visual cortex can sometimes direct actions towards 'unseen' targets located in areas of the visual field that are deemed 'blind' on the basis of static perimetry tests. Here, we show that a patient with a complete right homonymous hemianopia after a V1 lesion remains sensitive to the width of objects presented in her blind field but only when reaching out to grasp them in 'real-time'. A subsequent fMRI experiment revealed spared extra-geniculostriate pathways, which may mediate her preserved abilities. Taken together, the results support the view that visually guided movements can be mediated by pathways...

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When believing is seeing - The role of predictions in shaping visual perception

 

 

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When believing is seeing - The role of predictions in shaping visual perception

via The Quarterly Journal of Experimental Psychology: Articles recently published in by Król, Magdalena Ewa on 2/6/11

 

 

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