Age Trends in Cooperative and Competitive Decision-Making During Adolescence: A Computational Approach

Adolescence is marked by significant developmental changes in social decision-making, particularly in contexts requiring cooperation and competition. The present thesis investigates the computational mechanisms underlying developmental shifts in cooperative and competitive tacit coordination across adolescence. A total of 827 participants (526 females, 295 males; age range 9–48 years) completed dyadic coordination tasks with anonymous peers and no feedback: a cooperative coordination (stag-hunt game), a competitive coordination (entry game), as well as non-social lottery task. In each game, participants chose between a safe option yielding a guaranteed payoff and a risky option whose outcome depended on context. Behavioural analyses demonstrate age-related increases in risky choices and payoffs specific to cooperation, reflecting increasing propensity for cooperation. In contrast, competition shows age-related increases in switching between the risky and safe options and longer response times relative to cooperation and lottery, suggesting increasing competitive caution. Random-effects Bayesian model comparison identifies a model incorporating recursive reasoning levels (k), decision consistency (β), beliefs about others’ choices (k0 bias), and risk preference (ρ) as the best account of behaviour. All four parameters show significant developmental associations: k0 bias exhibits the strongest positive association with age (ρ = .20), followed by recursive reasoning (ρ = .19) and decision consistency (ρ = .18), whereas risk aversion declines with age (ρ = −.13). Optimistic beliefs about others’ choices are strongly associated with cooperative risk-taking, while greater recursive reasoning is associated with increased switching and longer response times in competition. Furthermore, recursive reasoning and decision consistency are positively associated with non-verbal reasoning abilities, while greater decision consistency is associated with greater centrality in social network. Overall, developmental shifts in recursive reasoning, decision consistency, and beliefs about others’ choices contribute to distinct age trends in cooperative and competitive decision-making, providing insights into normative social development and implications for atypical social functioning.