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Crowding, visual awareness, and their respective neural loci

In peripheral vision, object identification can be impeded when a target object is flanked by other objects. This phenomenon of crowding has been attributed to basic processes associated with image encoding by the visual system, but the neural origin of crowding is not known. Determining whether cro...

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Autores principales: Shin, Kilho, Chung, Susana T. L., Tjan, Bosco S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Association for Research in Vision and Ophthalmology 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5455068/
https://www.ncbi.nlm.nih.gov/pubmed/28549353
http://dx.doi.org/10.1167/17.5.18
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author Shin, Kilho
Chung, Susana T. L.
Tjan, Bosco S.
author_facet Shin, Kilho
Chung, Susana T. L.
Tjan, Bosco S.
author_sort Shin, Kilho
collection PubMed
description In peripheral vision, object identification can be impeded when a target object is flanked by other objects. This phenomenon of crowding has been attributed to basic processes associated with image encoding by the visual system, but the neural origin of crowding is not known. Determining whether crowding depends on subjective awareness of the flankers can provide information on the neural origin of crowding. However, recent studies that manipulated flanker awareness have yielded conflicting results. In the current study, we suppressed flanker awareness with two methods: interocular suppression (IOS) and adaptation-induced blindness (AIB). We tested two different types of stimuli: gratings and letters. With IOS, we found that the magnitude of crowding increased as the number of physical flankers increased, even when the observers did not report seeing any of the flankers. In contrast, when flanker awareness was manipulated with AIB, the magnitude of crowding increased with the number of perceived flankers. Our results show that whether crowding is contingent on awareness of the flankers depends on the method used to suppress awareness. In addition, our results imply that the locus of crowding is upstream from the neural locus of IOS and close to or downstream from that of AIB. Neurophysiology and neuroimaging studies jointly implicate mid-to-high level visual processing stages for IOS, while direct evidence regarding the neural locus of AIB is limited. The most consistent interpretation of our empirical findings is to place the neural locus of crowding at an early cortical site, such as V1 or V2.
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spelling pubmed-54550682017-06-04 Crowding, visual awareness, and their respective neural loci Shin, Kilho Chung, Susana T. L. Tjan, Bosco S. J Vis Article In peripheral vision, object identification can be impeded when a target object is flanked by other objects. This phenomenon of crowding has been attributed to basic processes associated with image encoding by the visual system, but the neural origin of crowding is not known. Determining whether crowding depends on subjective awareness of the flankers can provide information on the neural origin of crowding. However, recent studies that manipulated flanker awareness have yielded conflicting results. In the current study, we suppressed flanker awareness with two methods: interocular suppression (IOS) and adaptation-induced blindness (AIB). We tested two different types of stimuli: gratings and letters. With IOS, we found that the magnitude of crowding increased as the number of physical flankers increased, even when the observers did not report seeing any of the flankers. In contrast, when flanker awareness was manipulated with AIB, the magnitude of crowding increased with the number of perceived flankers. Our results show that whether crowding is contingent on awareness of the flankers depends on the method used to suppress awareness. In addition, our results imply that the locus of crowding is upstream from the neural locus of IOS and close to or downstream from that of AIB. Neurophysiology and neuroimaging studies jointly implicate mid-to-high level visual processing stages for IOS, while direct evidence regarding the neural locus of AIB is limited. The most consistent interpretation of our empirical findings is to place the neural locus of crowding at an early cortical site, such as V1 or V2. The Association for Research in Vision and Ophthalmology 2017-05-26 /pmc/articles/PMC5455068/ /pubmed/28549353 http://dx.doi.org/10.1167/17.5.18 Text en Copyright 2017 The Authors http://creativecommons.org/licenses/by-nc-nd/4.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
spellingShingle Article
Shin, Kilho
Chung, Susana T. L.
Tjan, Bosco S.
Crowding, visual awareness, and their respective neural loci
title Crowding, visual awareness, and their respective neural loci
title_full Crowding, visual awareness, and their respective neural loci
title_fullStr Crowding, visual awareness, and their respective neural loci
title_full_unstemmed Crowding, visual awareness, and their respective neural loci
title_short Crowding, visual awareness, and their respective neural loci
title_sort crowding, visual awareness, and their respective neural loci
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5455068/
https://www.ncbi.nlm.nih.gov/pubmed/28549353
http://dx.doi.org/10.1167/17.5.18
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