(Re)building cooperation: Effects of a cognitive intervention on cooperative behavior in games

Restoring cooperation after trust breaches remains a major hurdle in social, clinical, and organizational contexts. Yet, most interventions focus on initial trust formation rather than repair. We introduce a novel, online cognitive intervention—rooted in Dialectical Behavior Therapy—to reduce psychological reactivity and promote resilient cooperation. In a randomized controlled online trial (N = 318), participants played a Repeated Trust Game against an HMM-based adaptive agent trained on human data, ensuring dynamic, human-like responses under full experimental control. Compared to an active control, the cognitive intervention prevented retaliation following programmed trust violations and yielded significantly higher cooperative returns. Mixed-effects analysis revealed that while control participants became increasingly reciprocal over time (approaching tit-for-tat strategies), intervention participants maintained more stable cooperative behavior that was less contingent on partner investment levels. This change did not generalize to Prisoner's Dilemma, underscoring the intervention's specificity. These results validate HMM agents as a powerful experimental tool and suggest that targeted cognitive strategies may help support cooperative behavior; clinical efficacy and real-world deployment remain to be established.