Crowding by a repeating pattern

Rosen, Sarah; Pelli, Denis G.

doi:10.1167/15.6.10

Cited by 18 publications

(21 citation statements)

References 44 publications

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“…Gestalt approaches (21) argue that crowding occurs when the target is 'grouped' with the flankers, e.g. by forming a pattern with the flankers (44), and that it is reduced when the flankers form patterns that exclude the target (45). The topdown nature of grouping suggests that it should apply to the collection of features within the target as a whole, making it an allor-none process that is inconsistent with the dissociations we observe here.…”

Section: Discussioncontrasting

confidence: 60%

Dissociable effects of visual crowding on the perception of colour and motion

Greenwood

Parsons

2019

Preprint

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Our ability to recognise objects in peripheral vision is fundamentally limited by crowding, the deleterious effect of clutter that disrupts the recognition of features ranging from orientation and colour to motion and depth. Prior research is equivocal on whether this reflects a singular process that disrupts all features simultaneously or multiple processes that affect each independently. We examined crowding for motion and colour, two features that allow a strong test of feature independence. 'Cowhide' stimuli were presented 15 degrees in peripheral vision, either in isolation or surrounded by flankers to give crowding. Observers reported either the target hue (blue/purple) or its direction (clockwise/counterclockwise from upwards). We first established that both features show systematic crowded errors (predominantly biased towards the flanker identities) and selectivity for target-flanker similarity (with reduced crowding for dissimilar target/flanker elements). The multiplicity of crowding was then tested with observers identifying both features: a singular object-selective mechanism predicts that when crowding is weak for one feature and strong for the other that crowding should be all-or-none for both. In contrast, when crowding was weak for colour and strong for motion, errors were reduced for colour but remained for motion, and vice versa with weak motion and strong colour crowding. This double dissociation follows the predictions of independent crowding processes, suggesting that crowding can disrupt vision in a feature-specific manner. The ability to recognise one aspect of a cluttered scene, like colour, thus offers no guarantees for the correct recognition of other aspects, like motion. Significance statementThe fundamental limitation on our peripheral vision is crowding, the disruptive effect of image clutter on object recognition. Crowding is widely assumed to be a singular process, affecting all of the features (e.g. orientation, motion, and colour) within an object simultaneously. In contrast, we find a double dissociation for these disruptions: observers can make errors in judging the colour of a crowded object whilst correctly judging its movement direction, and vice versa. This dissociation is well described by a population-coding model that independently pools the motion and colour of target and flanker elements. We suggest that crowding may be a generic set of processes distributed throughout the visual system that independently simplify the representation of our visual field.

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Section: Discussioncontrasting

confidence: 60%

Dissociable effects of visual crowding on the perception of colour and motion

Greenwood

Parsons

2019

Preprint

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“…Adding flankers outside Bouma's window can improve performance contrary to theories a and b. It is important to note that adding elements outside Bouma's window can also increase crowding (Manassi et al, 2012;Rosen & Pelli, 2015;Saarela et al, 2010;Vickery, Shim, Chakravarthi, Jiang, & Luedeman, 2009). Hence, neither Bouma's window nor the number or extent of flankers determines crowding.…”

Section: Crowding Characteristics and Modelsmentioning

confidence: 99%

What crowding can tell us about object representations

et al. 2016

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In crowding, perception of a target usually deteriorates when flanking elements are presented next to the target. Surprisingly, adding further flankers can lead to a release from crowding. In previous work we showed that, for example, vernier offset discrimination at 9° of eccentricity deteriorated when a vernier was embedded in a square. Adding further squares improved performance. The more squares presented, the better the performance, extending across 20° of the visual field. Here, we show that very similar results hold true for shapes other than squares, including unfamiliar, irregular shapes. Hence, uncrowding is not restricted to simple and familiar shapes. Our results provoke the question of whether any type of shape is represented at any location in the visual field. Moreover, small changes in the orientation of the flanking shapes led to strong increases in crowding strength. Hence, highly specific shape-specific interactions across large parts of the visual field determine vernier acuity.

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“…This research appeared as a chapter in Rosen's unpublished Ph.D. thesis (Psychology Department, New York University, 2012). This paper is one of a set of papers using crowding to characterize object recognition (Rosen, Chakravarthi, & Pelli, 2014;Rosen & Pelli, 2014a, 2014b…”

Section: Acknowledgmentsmentioning

confidence: 99%

The Bouma law of crowding, revised: Critical spacing is equal across parts, not objects

2014

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Crowding is the inability to identify an object among flankers in the periphery. It is due to inappropriate incorporation of features from flanking objects in perception of the target. Crowding is characterized by measuring critical spacing, the minimum distance needed between a target and flankers to allow recognition. The existing Bouma law states that, at a given point and direction in the visual field, critical spacing, measured from the center of a target object to the center of a similar flanking object, is the same for all objects (Pelli & Tillman, 2008). Because flipping an object about its center preserves its center-to-center spacing to other objects, according to the Bouma law, crowding should be unaffected. However, because crowding is a result of feature combination, the location of features within an object might matter. In a series of experiments, we find that critical spacing is affected by the location of features within the flanker. For some flankers, a flip greatly reduces crowding even though it maintains target-flanker spacing and similarity. Our results suggest that the existing Bouma law applies to simple one-part objects, such as a single roman letter or a Gabor patch. Many objects consist of multiple parts; for example, a word is composed of multiple letters that crowd each other. To cope with such complex objects, we revise the Bouma law to say that critical spacing is equal across parts, rather than objects. This accounts for old and new findings.

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Crowding by a repeating pattern

Cited by 18 publications

References 44 publications

Dissociable effects of visual crowding on the perception of colour and motion

Dissociable effects of visual crowding on the perception of colour and motion

What crowding can tell us about object representations

The Bouma law of crowding, revised: Critical spacing is equal across parts, not objects

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