Abstract

Background: Cooperation skills are crucial for individual success in society. While research has often shown that adolescents exhibit fewer cooperative behaviors than adults in social dilemmas, the computational processes underlying such behavioral variations remain underexplored. Previous studies concluded that adolescents may have a deficiency in forming appropriate expectations of others' cooperative intentions due to underdeveloped mentalizing abilities (Theory of Mind); however, another possibility is that they may simply be driven by a selfish motive to exploit others.

Methods: To this end, the present study used a repeated version of the Prisoner's Dilemma Game (rPDG) to compare cooperative behaviors between adolescents (n = 127) and adults (n = 134). Participants were cooperating with a computer-simulated partner during rPDG (Figure 1a-c). Computational models with different assumptions were constructed and compared to explore the mental processes underlying cooperative decisions, ultimately testing the hidden variables driving behavioral variations between adolescents and adults.

Results: Consistent with previous research, adolescents exhibited less cooperation than adults, particularly following their partner's consistent cooperation (Figure 1d). Computational modeling revealed that the social reward model with asymmetric reinforcement learning algorithm provided the best explanation for the behaviors of both adolescents and adults (Figure 2). The best-fitting model revealed that, compared to adults, adolescents applied a higher positive learning rate (α+) and a lower negative learning rate (α-) when updating their expectations of partners' cooperation intention and exhibited less social preference (ω) for cooperation (Figure 3). In line with our hypothesis, adolescents did not exhibit inappropriate expectations regarding their partner's cooperative intentions compared to adults (Figure 4a-d); however, they perceived less intrinsic reward for reciprocity.

Conclusion: The lower levels of cooperation observed in adolescents stem from a selfish motive to exploit others rather than a deficiency in mentalizing or learning during social interactions. These findings have implications for educational approaches and strategies to foster adolescent cooperative behaviors.