Increased reward generalization underlies risky social decision-making in adolescents

Poster Session B - Sunday, April 14, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Amrita Lamba^1,2 (a_lamba@mit.edu), Matthew Nassar², Oriel FeldmanHall²; ¹MIT, ²Brown University

Adaptive learning hinges on accurate credit assignment—our ability to bind observed outcomes to the appropriate cause so that behavior can be flexibly tailored to a specific context. Our prior work suggests that the prefrontal cortex (PFC) allows such differentiation to unfold by selectively binding observed outcomes to the appropriate source in memory. In the current study, we compared how adolescents—a population characterized by increased sensitivity to social feedback and less matured PFC circuitry—assign credit in social situations. We used a cross-sectional design (N = 28 adults, N=26 adolescents) to examine how the development of key PFC pathways impacts learning in a trust task that requires careful differentiation between trustworthy and untrustworthy partners. A Reinforcement Learning model that quantities how precisely an individual updates their knowledge of each partner showed that adults are more precise when assigning credit for rewarding outcomes (i.e., carefully matching one’s trust behavior to each partner) compared to losses which were attributed to all partners. The precision of credit assignment was also mirrored in the distinctiveness of partner-specific neural representations in the PFC. In contrast, adolescents were less precise than adults at assigning credit, particularly for rewards, which were more likely to be attributed to all partners. This pattern was accompanied by riskier investments in the trust task and less differentiated neural representations in the PFC. These results provide initial evidence that the protracted development of prefrontal circuits may underlie reduced specificity of credit assignment in adolescents, facilitating a pattern of risky social decision-making.

Topic Area: EMOTION & SOCIAL: Other