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Modeling single-trial ERP reveals modulation of bottom-up face visual processing by top-down task constraints (in some subjects)

Rousselet, Guillaume A., Gaspar, Carl M., Wieczorek, Kacper and Pernet, Cyril R. 2011. Modeling single-trial ERP reveals modulation of bottom-up face visual processing by top-down task constraints (in some subjects). Frontiers in Psychology 10.3389/fpsyg.2011.00137

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Abstract

We studied how task constraints modulate the relationship between single-trial event-related potentials (ERPs) and image noise. Thirteen subjects performed two interleaved tasks: on different blocks, they saw the same stimuli, but they discriminated either between two faces or between two colors. Stimuli were two pictures of red or green faces that contained from 10 to 80% of phase noise, with 10% increments. Behavioral accuracy followed a noise dependent sigmoid in the identity task but was high and independent of noise level in the color task. EEG data recorded concurrently were analyzed using a single-trial ANCOVA: we assessed how changes in task constraints modulated ERP noise sensitivity while regressing out the main ERP differences due to identity, color, and task. Single-trial ERP sensitivity to image phase noise started at about 95–110ms post-stimulus onset. Group analyses showed a significant reduction in noise sensitivity in the color task compared to the identity task from about 140ms to 300ms post-stimulus onset. However, statistical analyses in every subject revealed different results: significant task modulation occurred in 8/13 subjects, one showing an increase and seven showing a decrease in noise sensitivity in the color task. Onsets and durations of effects also differed between group and single-trial analyses: at any time point only a maximum of four subjects (31%) showed results consistent with group analyses. We provide detailed results for all 13 subjects, including a shift function analysis that revealed asymmetric task modulations of single-trial ERP distributions. We conclude that, during face processing, bottom-up sensitivity to phase noise can be modulated by top-down task constraints, in a broad window around the P2, at least in some subjects.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Psychology
Subjects: B Philosophy. Psychology. Religion > BF Psychology
R Medicine > RE Ophthalmology
Uncontrolled Keywords: ERP, GLM, single-trial analyses, bootstrap, N170, individual differences, faces, noise
Additional Information: Pdf uploaded in accordance with publisher's policy at http://www.sherpa.ac.uk/romeo/issn/1664-1078/ (accessed 25/02/2014). This Document is Protected by copyright and was first published by Frontiers. All rights reserved. it is reproduced with permission.
Publisher: Frontiers Research Foundation
ISSN: 1664-1078
Date of First Compliant Deposit: 30 March 2016
Last Modified: 17 May 2023 21:18
URI: https://orca.cardiff.ac.uk/id/eprint/42754

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