The Neural Dynamics of Familiar Face Recognition

In real-life situations, the appearance of a person's face can vary substantially across different encounters, making face recognition a challenging task for the visual system. Recent fMRI decoding studies have suggested that face recognition is supported by identity representations located in regions of the occipitotemporal cortex. Here, we used EEG to elucidate the temporal emergence of these representations. Human participants viewed a set of highly variable face images of 4 highly familiar celebrities (2 males and 2 females), while performing an orthogonal task. Univariate analyses of event-related EEG responses revealed a pronounced differentiation between male and female faces, but not between identities of the same sex. Using multivariate representational similarity analysis, we observed a gradual emergence of face identity representations, with an increasing degree of invariance. Face identity information emerged rapidly, starting shortly after 100 ms from stimulus onset, but was modulated by sex differences and image similarities. From 400 ms after onset and predominantly in the right hemisphere, identity representations showed 2 invariance properties: 1) they equally discriminated identities of opposite sexes and of the same sex, and 2) they were tolerant to image-based variations. These invariant representations may be a crucial prerequisite for successful face recognition in everyday situations, where the appearance of a familiar person can vary drastically.