Money for me and money for friend: An ERP study of social reward processing in adolescents and adults.

Peer relations during adolescence contribute significantly to the development of socio-cognitive skills and pro-sociality. The current study probed the characteristics of adolescent socio-cognitive processing through a card game where they earn money for self and friend. We investigated the choice preference and temporal dynamics of information processing by measuring ERP responses to wins or losses (valence) directed toward self and friend (recipient). Choice data showed that despite adults and adolescents earning equivalent amounts across recipients combined, adults won significantly more for self than a friend; no such difference was found in adolescents. The ERPs in response to choice outcomes showed that the valence information was processed earlier (at P2) in adults, while it was processed later (at P3) in adolescents. Furthermore, a strong effect of recipient was present in adults later in the time course (at P3), while such an effect was weak in adolescents; if any, adolescents showed sensitivity to recipient information earlier at P2. These ERP data suggest a relatively equal allocation of the P3-mediated attentional process to both self and friend's outcomes in adolescents, which parallels the choice behavior. Collectively our results characterize adolescent pro-sociality toward friends, reflecting the importance of peer relationship during this unique developmental period.