The time course of implicit processing of facial features: an event-related potential study.

In this study, we used ERPs to investigate the time course of implicit face processing. More specifically, we utilized a masked priming paradigm to investigate implicit processing of the eyes and mouth in upright and inverted faces, using a prime duration of 33ms. Two types of prime-target pairs were used: (1) congruent (e.g., open eyes only in both prime and target); (2) incongruent (e.g., open eyes only in prime and open mouth only in target). The identity of the faces changed between prime and target. Participants pressed one button to indicate whether the target face's mouth was open, and another if the eyes were open. The behavioral results indicated a congruent priming effect for upright but not for inverted faces. The ERP results indicated a face orientation effect across all ERP components studied (P1, N1, P2, N170, N2, P3) starting at about 80ms, and a congruency/priming effect on late components (N2, P3), starting at about 200ms. The functional significance of these ERP effects is discussed in relation to unconscious perception and configural face processing.