Neurophysiological correlates of face and identity learning through naturalistic exposure

Abstract

Differential processing of familiar and unfamiliar faces is now well-established but surprisingly little is known about how familiarity develops over time. The aim of this thesis was to track the neural processes which accompany short- and long-term face and person learning, under more naturalistic conditions than those of previous, laboratory-based research. Using event-related brain potentials, the experiments examined how real-life learning affects the visual face representations (N250 familiarity effect) and the integration of person-related knowledge (Sustained Familiarity Effect, SFE). Chapter 2 revealed an increase in the N250 and the SFE from two to 14 months of familiarity but not afterwards, indicating that the first year of familiarity is critical for the development of the neural representations of visual familiarity and identity-specific knowledge. Chapter 3 tracked the development of these two effects during the first eight months of knowing a person and found a clear N250 and SFE at one month of knowing someone. While the N250 was fully established by five months of familiarity, indicating that the visual representations were fully developed substantially earlier than 14 months, no significant increase in the SFE was observed during the examined eight-month period, suggesting that the integration of identity-specific information needs longer to get fully established. Chapter 4 investigated face learning following a single brief real-life encounter and observed a significant N250 effect after a 10-minute interaction with an unfamiliar person, suggesting that 10 minutes are sufficient to establish initial visual representations. In sum, the present research suggests that image-independent visual face representations are initially established very quickly and get fully developed within the first five months of knowing a person. The integration of person-related knowledge, on the other hand, first emerges after one month of familiarity and gradually develops to the level of highly familiar identities by 14 months. These findings substantially improve our understanding of how we get to know people in everyday life by providing vital information about the time course of this process.