Saccade-confounded image statistics explain visual crowding

Nandy, Anirvan S.; Tjan, Bosco S.

doi:10.1038/nn.3021

Cited by 112 publications

(117 citation statements)

References 47 publications

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“…Contrary to recent suggestions that crowding and saccades are closely linked (37)(38)(39), four aspects of our data lead us to reject an inextricable linkage between these processes. First, although crowding and saccades show similar patterns of variation, saccadic precision is worse in the lower visual field than in the upper-the opposite pattern not only to crowding, but also to a wide range of perceptual tasks (24,25).…”

Section: Discussioncontrasting

confidence: 99%

“…Recent studies suggest that there may be a particularly strong link between these processes (37)(38)(39), despite the more general dissociation between perceptual and saccadic localization (40)(41)(42)(43) and their apparently distinct cortical routes (34). Our first aim was therefore to examine whether saccadic precision and crowding covary across the visual field by measuring the size of crowded interference zones and the precision of saccade landing positions ("saccade error zones") for the same stimuli in a range of visual-field locations.…”

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confidence: 99%

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Variations in crowding, saccadic precision, and spatial localization reveal the shared topology of spatial vision

Greenwood

Szinte

Sayim

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

121

152

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Visual sensitivity varies across the visual field in several characteristic ways. For example, sensitivity declines sharply in peripheral (vs. foveal) vision and is typically worse in the upper (vs. lower) visual field. These variations can affect processes ranging from acuity and crowding (the deleterious effect of clutter on object recognition) to the precision of saccadic eye movements. Here we examine whether these variations can be attributed to a common source within the visual system. We first compared the size of crowding zones with the precision of saccades using an oriented clock target and two adjacent flanker elements. We report that both saccade precision and crowded-target reports vary idiosyncratically across the visual field with a strong correlation across tasks for all participants. Nevertheless, both group-level and trial-by-trial analyses reveal dissociations that exclude a common representation for the two processes. We therefore compared crowding with two measures of spatial localization: Landolt-C gap resolution and three-dot bisection. Here we observe similar idiosyncratic variations with strong interparticipant correlations across tasks despite considerably finer precision. Hierarchical regression analyses further show that variations in spatial precision account for much of the variation in crowding, including the correlation between crowding and saccades. Altogether, we demonstrate that crowding, spatial localization, and saccadic precision show clear dissociations, indicative of independent spatial representations, whilst nonetheless sharing idiosyncratic variations in spatial topology. We propose that these topological idiosyncrasies are established early in the visual system and inherited throughout later stages to affect a range of higher-level representations.O ur sensitivity to visual stimuli varies substantially across the visual field with characteristic patterns that are evident across a wide range of tasks. Most notably, our ability to see fine detail decreases sharply as objects move into peripheral vision (1). These abilities are further disrupted by crowding, the impairment of object recognition in clutter, which also increases with eccentricity (2, 3). Both of these effects have been attributed to an overrepresentation of the fovea at the expense of peripheral vision, known as "cortical magnification" (4, 5), which has been observed in a range of retinotopically organized areas of the brain (6, 7). Here we ask whether other variations in visual sensitivity can similarly be attributed to topological principles within the visual system and consider whether these variations might share a common source.Variations across the visual field are particularly apparent with crowding, a process that presents the fundamental limitation on object recognition in peripheral vision (8). Crowding disrupts the recognition of a target object when flanker objects fall within a surrounding "interference zone." As well as increasing in size with eccentricity, these zones show an elliptical shap...

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Section: Discussioncontrasting

confidence: 99%

mentioning

confidence: 99%

Variations in crowding, saccadic precision, and spatial localization reveal the shared topology of spatial vision

Greenwood

Szinte

Sayim

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

121

152

View full text Add to dashboard Cite

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“…Basic detectors signal the presence of the target (hence, target detection is not impaired). At the integration stage, feature location is lost since, for example, receptive fields are large and features are jumbled (Greenwood, Bex, & Dakin, 2009;Pelli et al, 2004) or inappropriate representations of image statistics are acquired due to saccade programming (Nandy & Tjan, 2012). In foveal vision, often lateral inhibition is proposed as a mechanism of interference by flankers (Westheimer & Hauske, 1975).…”

Section: Neural Mechanismsmentioning

confidence: 99%

Grouping, pooling, and when bigger is better in visual crowding

2012

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In crowding, perception of a target is strongly deteriorated by nearby elements. Crowding is often explained by pooling models predicting that adding flankers increases crowding. In contrast, the centroid hypothesis proposes that adding flankers decreases crowding--"bigger is better." In foveal vision, we have recently shown that adding flankers can increase or decrease crowding depending on whether the target groups or ungroups from the flankers. We have further shown how configural effects, such as good and global Gestalt, determine crowding. Foveal and peripheral crowding do not always reveal the same characteristics. Here, we show that the very same grouping and Gestalt results of foveal vision are also found in the periphery. These results can neither be explained by simple pooling nor by centroid models. We discuss when bigger is better and how grouping might shape crowding.

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“…Finally, the zone of crowding is not circular but, instead, exhibits a radialtangential anisotropy, such that flankers positioned along the radial axis from the fovea to the target will produce more crowding than those placed tangentially to this axis (Toet & Levi, 1992). Recently, Nandy and Tjan (2012) showed that all of these characteristics of crowding can be explained as a consequence of saccades confounding the statistics of natural images. However, identifying a central letter is very different from identifying a word.…”

Section: Intraword Spacing Effectsmentioning

confidence: 99%

Effects of intraword and interword spacing on eye movements during reading: Exploring the optimal use of space in a line of text

Slattery

Rayner

2013

Atten Percept Psychophys

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Two eye movement experiments investigated intraword spacing (the space between letters within words) and interword spacing (the space between words) to explore the influence these variables have on eye movement control during reading. Both variables are important factors in determining the optimal use of space in a line of text, and fonts differ widely in how they employ these spaces. Prior research suggests that the proximity of flanking letters influences the identification of a central letter via lateral inhibition or crowding. If so, decrements in intraword spacing may produce inhibition in word processing. Still other research suggests that increases in intraword spacing can disrupt the integrity of word units. In English, interword spacing has a large influence on word segmentation and is important for saccade target selection. The results indicate an interplay between intra-and interword spacing that influences a font's readability. Additionally, these studies highlight the importance of word segmentation processes and have implications for the nature of lexical processing (serial vs. parallel).

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Saccade-confounded image statistics explain visual crowding

Cited by 112 publications

References 47 publications

Variations in crowding, saccadic precision, and spatial localization reveal the shared topology of spatial vision

Variations in crowding, saccadic precision, and spatial localization reveal the shared topology of spatial vision

Grouping, pooling, and when bigger is better in visual crowding

Effects of intraword and interword spacing on eye movements during reading: Exploring the optimal use of space in a line of text

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