Asymmetric neural responses for facial expressions and anti-expressions

dc.contributor.authorGwinn, O Scott
dc.contributor.authorMatera, Courtney N
dc.contributor.authorO'Neil, Sean F
dc.contributor.authorWebster, Michael A
dc.descriptionThis manuscript version is made available under the CC-BY-NC-ND 4.0 license: which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. This author accepted manuscript is made available following 18 month embargo from date of publication (Sept 2018) in accordance with the publisher’s archiving policyen_US
dc.description.abstractFace recognition requires identifying both the invariant characteristics that distinguish one individual from another and the variations within the individual that correspond to emotional expressions. Both have been postulated to be represented via a norm-based code, in which identity or expression are represented as deviations from an average or neutral prototype. We used Fast Periodic Visual Stimulation (FPVS) with electroencephalography (EEG) to compare neural responses for neutral faces, expressions and anti-expressions. Anti-expressions are created by projecting an expression (e.g. a happy face) through the neutral face to form the opposite facial shape (anti-happy). Thus expressions and anti-expressions differ from the norm by the same “configural” amount and thus have equivalent but opposite status with regard to their shape, but differ in their ecological validity. We examined whether neural responses to these complementary stimulus pairs were equivalent or asymmetric, and also tested for norm-based coding by comparing whether stronger responses are elicited by expressions and anti-expressions than neutral faces. Observers viewed 20 s sequences of 6 Hz alternations of neutral faces and expressions, neutral faces and anti-expressions, and expressions and anti-expressions. Responses were analyzed in the frequency domain. Significant responses at half the frequency of the presentation rate (3 Hz), indicating asymmetries in responses, were observed for all conditions. Inversion of the images reduced the size of this signal, indicating these asymmetries are not solely due to differences in the low-level properties of the images. While our results do not preclude a norm-based code for expressions, similar to identity, this representation (as measured by the FPVS EEG responses) may also include components sensitive to which configural distortions form meaningful expressions.en_US
dc.description.sponsorshipThis work was supported by grants from the National Institutes of Health (EY-10834 to MW; EY-023268 to FJ), with further support for core facilities provided by COBRE P20GM 103650.en_US
dc.identifier.citationGwinn, O. S., Matera, C. N., O’Neil, S. F., & Webster, M. A. (2018). Asymmetric neural responses for facial expressions and anti-expressions. Neuropsychologia, 119, 405–416.en_US
dc.rights© 2018 Elsevier Ltd. This manuscript version is made available under the CC-BY-NC-ND 4.0 license:
dc.rights.holder© 2018 Elsevier Ltd.en_US
dc.subjectFacial expressionsen_US
dc.subjectNorm-based codingen_US
dc.titleAsymmetric neural responses for facial expressions and anti-expressionsen_US
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