The Time Course of Face Representations during Perception and Working Memory Maintenance

Successful social communication requires accurate perception and maintenance of invariant (face identity) and variant (facial expression) aspects of faces. While numerous studies investigated how face identity and expression information is extracted from faces during perception, less is known about the temporal aspects of the face information during perception and working memory (WM) maintenance. To investigate how face identity and expression information evolve over time, I recorded electroencephalography (EEG) while participants were performing a face WM task where they remembered a face image and reported either the identity or the expression of the face image after a short delay. Using multivariate event-related potential (ERP) decoding analyses, I found that the two types of information exhibited dissociable temporal dynamics: Although face identity was decoded better than facial expression during perception, facial expression was decoded better than face identity during WM maintenance. Follow-up analyses suggested that this temporal dissociation was driven by differential maintenance mechanisms: Face identity information was maintained in a more "activity-silent" manner compared to facial expression information, presumably because invariant face information does not need to be actively tracked in the task. Together, these results provide important insights into the temporal evolution of face information during perception and WM maintenance.