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Asymmetric compression of representational space for object animacy categorization under degraded viewing conditions

Grootswagers, T, Ritchie, B, Wardle, SG, Heathcote, A ORCID: 0000-0003-4324-5537 and Carlson, TA 2017 , 'Asymmetric compression of representational space for object animacy categorization under degraded viewing conditions' , Journal of Cognitive Neuroscience, vol. 29, no. 12 , pp. 1995-2010 , doi:

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Animacy is a robust organizing principle amongst object categoryrepresentationsinthehumanbrain.Usingmultivariatepatternanalysismethods(MVPA),ithasbeenshownthatdistancetothedecisionboundaryofaclassifiertrained to discriminate neural activation patterns for animate and inanimateobjects correlates with observer reaction times for the same animacycategorization task (Carlson, Ritchie, Kriegeskorte, Durvasula, & Ma, 2014;Ritchie, Tovar, & Carlson, 2015). Using MEG decoding, we tested if the samerelationship holds when a stimulus manipulation (degradation) increases taskdifficulty, which we predicted would systematically decrease the distance ofactivationpatterns from thedecisionboundary,andincrease reaction times. Inaddition,we testedwhetherdistance to the classifier boundary correlateswithdrift rates in the Linear Ballistic Accumulator(Brown & Heathcote, 2008).Wefound that distance to the classifier boundary correlated with reaction time,accuracy,anddriftratesinananimacycategorizationtask.Splitbyanimacy,thecorrelationsbetweenbrainandbehaviorweresustainedforlongeroverthetimecourseforanimatethanforinanimatestimuli.Interestingly,whenexaminingthedistance to the classifier boundary during the peak correlation between brain and behavior, we found that only degraded versions of animate, but notinanimate, objects had systematically shifted towards the classifier decisionboundaryaspredicted.Ourresultssupportanasymmetryintherepresentationofanimateandinanimateobjectcategoriesinthehumanbrain.

Item Type: Article
Authors/Creators:Grootswagers, T and Ritchie, B and Wardle, SG and Heathcote, A and Carlson, TA
Journal or Publication Title: Journal of Cognitive Neuroscience
Publisher: M I T Press
ISSN: 0898-929X
DOI / ID Number:
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Copyright 2017 Massachusetts Institute of Technology

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