The generality of the critical spacing for crowded optotypes: From Bouma to the 21st century

Coates, Daniel R.; Ludowici, Charles; Chung, Susana T. L.

doi:10.1167/jov.21.11.18

Cited by 13 publications

(17 citation statements)

References 75 publications

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“…Theoretically, results from just an unflanked measurement and a single nominal spacing may be sufficient to determine the critical spacing ( Song et al., 2014 ), although this depends on assumptions about testing conditions. Critical spacings obtained with this procedure have been shown to be consistent with critical spacings obtained with the more commonplace procedure of fixing the letter size and testing different absolute flanker spacings ( Coates et al., 2021 ). On the other hand, this procedure is sensitive to limitations from both target resolution as well as influence from the flankers, so the source of errors in a given condition may not be readily apparent, although we discuss an analysis that addresses this issue.…”

Section: Methodssupporting

confidence: 65%

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Cortical distance unifies the extent of parafoveal contour interactions

et al. 2022

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It is well known that crowding, the disruptive influence of flanking items on identification of targets, is the primary limiting factor to object identification in the periphery, while limits in the fovea are more determined by the ability to resolve individual items. Whether this is a dichotomous or merely a quantitative difference, and the transition between these two regimes, has remained unexplained. Here, using an adaptive optics system for optimal control of optical and stimulus factors, we measured threshold acuity for identification of Tumbling Es flanked by bars at a variety of flanker spacings and eight eccentricities in the parafovea. Thresholds at each eccentricity were influenced by resolution, contour interaction, and a saturating pedestal effect. When target-flanker spacing was plotted in terms of cortical distance, a single canonical clipped-line fit unified the resultant curves. The critical spacing for letters flanked by bars was found to be 1.3 to 1.5 cortical millimeters, corresponding to approximately 0.1*E outside the fovea.

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Section: Methodssupporting

confidence: 65%

“…The more common approach nowadays is to test target and flankers of a single size at different spacings and construct a performance versus spacing curve ( Toet & Levi, 1992 ). The two methods give comparable results for critical spacing, with empirical and theoretical issues summarized in Coates et al. (2021) .…”

Section: Methodsmentioning

confidence: 71%

Cortical distance unifies the extent of parafoveal contour interactions

et al. 2022

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“…Although this method confounds size and separation by varying both, the extent of amblyopic and peripheral crowding is limited by center-to-center separation and not target size ( Hariharan, Levi, & Klein, 2005 ). As such, only the variations in center-to-center separation should affect the strength of crowding and thus the measurement of its extent ( Levi, Song, & Pelli, 2007 ; Song, Levi, & Pelli, 2014 ; Coates, Ludowici, & Chung, 2021 ). The resulting threshold gave the upper bound for the sizes and target–flanker separations used in the orientation-matching task, ensuring that stimuli were placed within the spatial extent of crowding.…”

Section: Methodsmentioning

confidence: 99%

Crowding changes appearance systematically in peripheral, amblyopic, and developing vision

et al. 2022

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Visual crowding is the disruptive effect of clutter on object recognition. Although most prominent in adult peripheral vision, crowding also disrupts foveal vision in typically developing children and those with strabismic amblyopia. Do these crowding effects share the same mechanism? Here we exploit observations that crowded errors in peripheral vision are not random: Target objects appear either averaged with the flankers (assimilation) or replaced by them (substitution). If amblyopic and developmental crowding share the same mechanism, then their errors should be similarly systematic. We tested foveal vision in children aged 3 to 8 years with typical vision or strabismic amblyopia and peripheral vision in typical adults. The perceptual effects of crowding were measured by requiring observers to adjust a reference stimulus to match the perceived orientation of a target “Vac-Man” element. When the target was surrounded by flankers that differed by ± 30°, all three groups (adults and children with typical or amblyopic vision) reported orientations between the target and flankers (assimilation). Errors were reduced with ± 90° differences but primarily matched the flanker orientation (substitution) when they did occur. A population pooling model of crowding successfully simulated this pattern of errors in all three groups. We conclude that the perceptual effects of amblyopic and developing crowding are systematic and resemble the near periphery in adults, suggesting a common underlying mechanism.

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“…Although this method confounds size and separation by varying both, the extent of amblyopic and peripheral crowding are limited by centre-to-centre separation and not target size (Hariharan, Levi, & Klein, 2005). As such, it is only the variations in centre-to-centre separation that should affect the strength of crowding, and thus the measurement of its extent (Levi, Song, & Pelli, 2007; Song, Levi, & Pelli, 2014; Coates, Ludowici, & Chung, 2021). The resulting threshold gave the upper bound for the sizes and target-flanker separations used in the orientation-matching task, ensuring that stimuli were placed within the spatial extent of crowding.…”

Section: Methodsmentioning

confidence: 99%

Crowding changes appearance systematically in peripheral, amblyopic, and developing vision

Kalpadakis-Smith

Tailor

Dahlmann‐Noor

et al. 2021

Preprint

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Visual crowding is the disruptive effect of clutter on object recognition. Although most prominent in adult peripheral vision, crowding also disrupts foveal vision in typically-developing children and those with strabismic amblyopia. Do these crowding effects share the same mechanism? Here we exploit observations that crowded errors in peripheral vision are not random: target objects appear either averaged with the flankers (assimilation), or replaced by them (substitution). If amblyopic and developmental crowding share the same mechanism then their errors should be similarly systematic. We tested foveal vision in children aged 3-9 years with typical vision or strabismic amblyopia, and peripheral vision in adults. The perceptual effects of crowding were measured by requiring observers to adjust a reference stimulus to match the perceived orientation of a target ‘Vac-Man’ element. When the target was surrounded by flankers that differed by ±30°, adults and children reported orientations between the target and flankers (assimilation). Errors were reduced with ±90° differences, but primarily matched the flanker orientation (substitution) when they did occur. A population pooling model of crowding successfully simulated this pattern of errors in all three groups. We conclude that the perceptual effects of amblyopic and developing crowding are systematic and resemble the near periphery in adults, suggesting a common underlying mechanism.

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The generality of the critical spacing for crowded optotypes: From Bouma to the 21st century

Cited by 13 publications

References 75 publications

Cortical distance unifies the extent of parafoveal contour interactions

Cortical distance unifies the extent of parafoveal contour interactions

Crowding changes appearance systematically in peripheral, amblyopic, and developing vision

Crowding changes appearance systematically in peripheral, amblyopic, and developing vision

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