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dc.contributor.authorWoolgar, Alexandra
dc.contributor.authorGolland, Polina
dc.contributor.authorBode, Stefan
dc.date.accessioned2015-12-13T20:26:14Z
dc.date.available2015-12-13T20:26:14Z
dc.date.issued2014-05
dc.identifier.issn10538119
dc.identifier.issn1095-9572
dc.identifier.urihttp://hdl.handle.net/1721.1/100221
dc.description.abstractMultivoxel pattern analysis (MVPA) is a sensitive and increasingly popular method for examining differences between neural activation patterns that cannot be detected using classical mass-univariate analysis. Recently, Todd et al. (“Confounds in multivariate pattern analysis: Theory and rule representation case study”, 2013, NeuroImage 77: 157–165) highlighted a potential problem for these methods: high sensitivity to confounds at the level of individual participants due to the use of directionless summary statistics. Unlike traditional mass-univariate analyses where confounding activation differences in opposite directions tend to approximately average out at group level, group level MVPA results may be driven by any activation differences that can be discriminated in individual participants. In Todd et al.'s empirical data, factoring out differences in reaction time (RT) reduced a classifier's ability to distinguish patterns of activation pertaining to two task rules. This raises two significant questions for the field: to what extent have previous multivoxel discriminations in the literature been driven by RT differences, and by what methods should future studies take RT and other confounds into account? We build on the work of Todd et al. and compare two different approaches to remove the effect of RT in MVPA. We show that in our empirical data, in contrast to that of Todd et al., the effect of RT on rule decoding is negligible, and results were not affected by the specific details of RT modelling. We discuss the meaning of and sensitivity for confounds in traditional and multivoxel approaches to fMRI analysis. We observe that the increased sensitivity of MVPA comes at a price of reduced specificity, meaning that these methods in particular call for careful consideration of what differs between our conditions of interest. We conclude that the additional complexity of the experimental design, analysis and interpretation needed for MVPA is still not a reason to favour a less sensitive approach.en_US
dc.description.sponsorshipNational Science Foundation (U.S.). Division of Information & Intelligent Systems (Collaborative Research in Computational Neuroscience 0904625)en_US
dc.description.sponsorshipNational Institutes of Health (U.S.) (National Institute for Biomedical Imaging and Bioengineering (U.S.)/National Alliance for Medical Image Computing (U.S.) U54-EB005149) )en_US
dc.description.sponsorshipNational Institutes of Health (U.S.) (National Institute for Biomedical Imaging and Bioengineering (U.S.)/Neuroimaging Analysis Center (U.S.) P41-EB015902)en_US
dc.language.isoen_US
dc.publisherelsen_US
dc.relation.isversionofhttp://dx.doi.org/10.1016/j.neuroimage.2014.04.059en_US
dc.rightsCreative Commons Attribution-NonCommercial-NoDerivs Licenseen_US
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/en_US
dc.sourcePMCen_US
dc.titleCoping with confounds in multivoxel pattern analysis: What should we do about reaction time differences? A comment on Todd, Nystrom & Cohen 2013en_US
dc.typeArticleen_US
dc.identifier.citationWoolgar, Alexandra, Polina Golland, and Stefan Bode. “Coping with Confounds in Multivoxel Pattern Analysis: What Should We Do About Reaction Time Differences? A Comment on Todd, Nystrom & Cohen 2013.” NeuroImage 98 (September 2014): 506–512.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Electrical Engineering and Computer Scienceen_US
dc.contributor.mitauthorGolland, Polinaen_US
dc.relation.journalNeuroImageen_US
dc.eprint.versionAuthor's final manuscripten_US
dc.type.urihttp://purl.org/eprint/type/JournalArticleen_US
eprint.statushttp://purl.org/eprint/status/PeerRevieweden_US
dspace.orderedauthorsWoolgar, Alexandra; Golland, Polina; Bode, Stefanen_US
dc.identifier.orcidhttps://orcid.org/0000-0003-2516-731X
mit.licensePUBLISHER_CCen_US


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