Alice Nevard¹, Soazig Casteau¹, Ulrik Beierholm¹, Holger Wiese¹; ¹Durham University

Learning a new face can be described as forming a robust representation over time that allows for recognition in novel situations. Event-related potential research has linked this process with more negative amplitudes for learnt compared to novel faces at occipito-temporal channels from ~200 ms onwards. While this N250 effect represents robust learning, its amplitude is typically small - reflecting limited exposure to novel faces, which are typically learnt in a single session. The current research examines how new face representations are established over multiple sessions by comparing the N250 after repeatedly meeting a new person. In pre-training sessions, participants saw highly variable ambient images of the “to be learnt face”, an “unmatched face” and a “matched” identity, the latter resembling the first with respect to age, gender, hair colour and ethnicity. In subsequent sessions across four days, participants first had a ten-minute in-person interaction with the same learnt identity, followed by a test phase in which participants saw ambient images of the three identities. While new images were used in all sessions, the learnt and unmatched identities were repeated. However, a new matched identity was presented in each session. There were no differences in the N250 in the pre-training session. However, after one interaction, N250 responses were larger for the learnt face compared to the unmatched identity. Critically, this effect was substantially enhanced after four interactions. Moreover, learning effects in comparison to the matched faces were generally small. Our findings show how representations of novel faces build up with repeated exposure. Importantly, while in-person interactions provide sufficient information for building such representations over multiple sessions, repeatedly viewing ambient images of the same person does not.