Dataset Information

A Unifying Model of Orientation Crowding in Peripheral Vision.

ABSTRACT: Peripheral vision is fundamentally limited not by the visibility of features, but by the spacing between them [1]. When too close together, visual features can become "crowded" and perceptually indistinguishable. Crowding interferes with basic tasks such as letter and face identification and thus informs our understanding of object recognition breakdown in peripheral vision [2]. Multiple proposals have attempted to explain crowding [3], and each is supported by compelling psychophysical and neuroimaging data [4-6] that are incompatible with competing proposals. In general, perceptual failures have variously been attributed to the averaging of nearby visual signals [7-10], confusion between target and distractor elements [11, 12], and a limited resolution of visual spatial attention [13]. Here we introduce a psychophysical paradigm that allows systematic study of crowded perception within the orientation domain, and we present a unifying computational model of crowding phenomena that reconciles conflicting explanations. Our results show that our single measure produces a variety of perceptual errors that are reported across the crowding literature. Critically, a simple model of the responses of populations of orientation-selective visual neurons accurately predicts all perceptual errors. We thus provide a unifying mechanistic explanation for orientation crowding in peripheral vision. Our simple model accounts for several perceptual phenomena produced by crowding of orientation and raises the possibility that multiple classes of object recognition failures in peripheral vision can be accounted for by a single mechanism.

SUBMITTER: Harrison WJ

PROVIDER: S-EPMC4792514 | biostudies-literature | 2015 Dec

REPOSITORIES: biostudies-literature

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A Unifying Model of Orientation Crowding in Peripheral Vision.

Harrison William J WJ Bex Peter J PJ

Current biology : CB 20151125 24

Peripheral vision is fundamentally limited not by the visibility of features, but by the spacing between them [1]. When too close together, visual features can become "crowded" and perceptually indistinguishable. Crowding interferes with basic tasks such as letter and face identification and thus informs our understanding of object recognition breakdown in peripheral vision [2]. Multiple proposals have attempted to explain crowding [3], and each is supported by compelling psychophysical and neur ...[more]

PMID: 26628010

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Project description:Peripheral vision has different functional priorities for mammals than foveal vision. One of its roles is to monitor the environment while central vision is focused on the current task. Becoming distracted too easily would be counterproductive in this perspective, so the brain should react to behaviourally relevant changes. Gist processing is good for this purpose, and it is therefore not surprising that evidence from both functional brain imaging and behavioural research suggests a tendency to generalize and blend information in the periphery. This may be caused by the balance of perceptual influence in the periphery between bottom-up (i.e., sensory information) and top-down (i.e., prior or contextual information) processing channels. Here, we investigated this interaction behaviourally using a peripheral numerosity discrimination task with top-down and bottom-up manipulations. Participants compared numerosity between the left and right peripheries of a screen. Each periphery was divided into a centre and a surrounding area, only one of which was a task relevant target region. Our top-down task modulation was the instruction which area to attend - centre or surround. We varied the signal strength by altering the stimuli durations i.e., the amount of information presented/processed (as a combined bottom-up and recurrent top-down feedback factor). We found that numerosity perceived in target regions was affected by contextual information in neighbouring (but irrelevant) areas. This effect appeared as soon as stimulus duration allowed the task to be reliably performed and persisted even at the longest duration (1 s). We compared the pattern of results with an ideal-observer model and found a qualitative difference in the way centre and surround areas interacted perceptually in the periphery. When participants reported on the central area, the irrelevant surround would affect the response as a weighted combination - consistent with the idea of a receptive field focused in the target area to which irrelevant surround stimulation leaks in. When participants report on surround, we can best describe the response with a model in which occasionally the attention switches from task relevant surround to task irrelevant centre - consistent with a selection model of two competing streams of information. Overall our results show that the influence of spatial context in the periphery is mandatory but task dependent.

Dataset Information

A Unifying Model of Orientation Crowding in Peripheral Vision.

Publications

A Unifying Model of Orientation Crowding in Peripheral Vision.

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