The Late Positive Potential is Associated with Serial Dependence Effects in Facial Identity

The visual system can exploit knowledge about temporal contexts in two ways. Attractive serial dependence (SD) can facilitate stability by biasing current stimulus judgments toward recent stimulus history, while repulsive SD can promote change detection by biasing current judgments away from recent stimulus history. This study investigated the co-occurrence of repulsive and attractive SD across facial identity similarity using electroencephalography. Participants performed a matching task with morphed facial identities at varying visibility levels. Results revealed repulsive SD effects for similar faces and attractive SD effects for dissimilar faces, regardless of visibility. Event-related potential analysis showed no significant effects of facial similarity on the N170 and N250r, while the Late Positive Potential (LPP) was amplified for dissimilar faces and attenuated for similar faces. Regression analysis revealed a functional connection between the LPP and attractive, but not repulsive, SD effects. Topographical analysis indicated distinct distributions for repulsive and attractive SD effects within the LPP time-window. These findings suggest that the LPP, possibly reflecting attention-dependent comparison processes, contributes to attractive SD in facial identity. Overall, repulsive and attractive SD effects may rely on partially distinct neural generators, indicating that segregation and integration processes in SD are not due to a common underlying mechanism.