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Dynamics of trimming the content of face representations for categorization in the brain

van Rijsbergen, N.J., and Schyns, P.G. (2009) Dynamics of trimming the content of face representations for categorization in the brain. PLoS Computational Biology, 5 (11). e1000561. ISSN 1553-734X (doi:10.1371/journal.pcbi.1000561)

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Publisher's URL: http://www.ploscompbiol.org/article/info%3Adoi%2F10.1371%2Fjournal.pcbi.1000561

Abstract

To understand visual cognition, it is imperative to determine when, how and with what information the human brain categorizes the visual input. Visual categorization consistently involves at least an early and a late stage: the occipito-temporal N170 event related potential related to stimulus encoding and the parietal P300 involved in perceptual decisions. Here we sought to understand how the brain globally transforms its representations of face categories from their early encoding to the later decision stage over the 400 ms time window encompassing the N170 and P300 brain events. We applied classification image techniques to the behavioral and electroencephalographic data of three observers who categorized seven facial expressions of emotion and report two main findings: (1) Over the 400 ms time course, processing of facial features initially spreads bilaterally across the left and right occipito-temporal regions to dynamically converge onto the centro-parietal region; (2) Concurrently, information processing gradually shifts from encoding common face features across all spatial scales (e.g. the eyes) to representing only the finer scales of the diagnostic features that are richer in useful information for behavior (e.g. the wide opened eyes in 'fear'; the detailed mouth in 'happy'). Our findings suggest that the brain refines its diagnostic representations of visual categories over the first 400 ms of processing by trimming a thorough encoding of features over the N170, to leave only the detailed information important for perceptual decisions over the P300.

Item Type:Article
Additional Information:This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Status:Published
Refereed:Yes
Glasgow Author(s):Schyns, Prof Philippe and Van Rijsbergen, Dr Nicola
Authors: van Rijsbergen, N.J., and Schyns, P.G.
College/School:College of Medical Veterinary and Life Sciences > Institute of Neuroscience and Psychology > Cognitive Neuroimaging and Neuroengineering Technologies
College of Science and Engineering > School of Psychology
Journal Name:PLoS Computational Biology
Publisher:Public Library of Science
ISSN:1553-734X
ISSN (Online):1553-7358
Copyright Holders:Copyright © 2009 van Rijsbergen, Schyns.
First Published:First published in PLoS Computational Biology 2009 5(11): e1000561
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
449881Social interaction - a cognitive-neurosciences approachSimon GarrodEconomic & Social Research Council (ESRC)RES-060-25-0010Cognitive Neuroimaging & Neuroengineering Technologies

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