A Cognitive Model of Dynamic Cooperation With Varied Interdependency Information

We analyze the dynamics of repeated interaction of two players in the Prisoner's Dilemma (PD) under various levels of interdependency information and propose an instance‐based learning cognitive model (IBL‐PD) to explain how cooperation emerges over time. Six hypotheses are tested regarding how a player accounts for an opponent's outcomes: the selfish hypothesis suggests ignoring information about the opponent and utilizing only the player's own outcomes; the extreme fairness hypothesis weighs the player's own and the opponent's outcomes equally; the moderate fairness hypothesis weighs the opponent's outcomes less than the player's own outcomes to various extents; the linear increasing hypothesis increasingly weighs the opponent's outcomes at a constant rate with repeated interactions; the hyperbolic discounting hypothesis increasingly and nonlinearly weighs the opponent's outcomes over time; and the dynamic expectations hypothesis dynamically adjusts the weight a player gives to the opponent's outcomes, according to the gap between the expected and the actual outcomes in each interaction. When players lack explicit feedback about their opponent's choices and outcomes, results are consistent with the selfish hypothesis; however, when this information is made explicit, the best predictions result from the dynamic expectations hypothesis.     

When competition merges people's behavior: Interdependency activates shared action representations

Previous research suggests that friendly, cooperative situations cause one to integrate a co-actor's actions into one's own action system. Departing from an interdependency perspective, we predict the activation of shared action representations even in hostile, competitive situations as a result of attending to the intentions of the co-actor. To test this, in Experiment 1 we manipulated the interdependency between actor and co-actor in a joint Simon task and observed a stronger activation of shared action representations in a cooperative as well as competitive context compared to an independent context. Experiment 2 replicated the competitive context effect on activation of shared action representations and provided additional evidence for the mediating role of attending to others’ intentions by taking into account the individual tendency to attend to others’ intentions. Together, our findings suggest that interdependency merges people's behavior even in competitive contexts, which we argue encourage actors to attend to others’ intentions.