Social Norm Dynamics from the Conflict between Short-TermConformity and Long-Term Consequences: Cognitive–SocialSimulation

Social norms can provide immediate gains through local alignment with others, yet they are also constrained by collective consequences arising from the accumulation of individual actions. Grounded in dual-process theory, this study investigates how normative behavior is formed, bifurcates, and stabilizes when two competing signals operate on different time scales: a short-term local conformity reward and a delayed long-term collective penalty. Agents repeatedly choose between two actions (pull/keep). In each round, they receive a reward proportional to their agreement with neighbors; at fixed intervals, an assessment of collective harm is imposed as a delayed penalty. Decision making follows Instance-Based Learning Theory (PyIBL). We conducted simulations manipulating cognitive reward structure (short- vs. long-term incentives) and social relations. Overall, agents exhibited a bias toward utilitarian decisions, while outcomes frequently showed strong path-dependent polarization. This polarization was more pronounced in small-world networks that approximate human social structures. Cognitively, manipulating memory decay revealed that higher decay rates strengthened the influence of long-term rewards, shifting attention beyond immediate conformity gains. Additional simulations that removed long-term rewards showed that these social effects persisted while utilisation bias was diminished. These results show that social norms emerge from the interaction between cognitive processes and social structure.