Abstract
Understanding how to design agents that sustain cooperation in multi-agent systems has been a long-lasting goal in distributed artificial intelligence. Proposed solutions rely on identifying free-riders and avoiding cooperating or interacting with them. These mechanisms of social control are traditionally studied in games with linear and deterministic payoffs, such as the prisoner’s dilemma or the public goods game. In reality, however, agents often face dilemmas in which payoffs are uncertain and non-linear, as collective success requires a minimum number of cooperators. The collective risk dilemma (CRD) is one of these games, and it is unclear whether the known mechanisms of cooperation remain effective in this case. Here we study the emergence of cooperation in CRD through partner-based selection. First, we discuss an experiment in which groups of humans and robots play a CRD. This experiment suggests that people only prefer cooperative partners when they lose a previous game (i.e., when collective success was not previously achieved). Secondly, we develop an evolutionary game theoretical model pointing out the evolutionary advantages of preferring cooperative partners only when a previous game was lost. We show that this strategy constitutes a favorable balance between strictness (only interact with cooperators) and softness (cooperate and interact with everyone), thus suggesting a new way of designing agents that promote cooperation in CRD. We confirm these theoretical results through computer simulations considering a more complex strategy space. Third, resorting to online human–agent experiments, we observe that participants are more likely to accept playing in a group with one defector when they won in a previous CRD, when compared to participants that lost the game. These empirical results provide additional support to the human predisposition to use outcome-based partner selection strategies in human–agent interactions.
Highlights
Cooperation between self-interested agents has been a fundamental research topic in economics [20] and evolutionary biology [41]
In order to assert our hypotheses, we run a Mixed analysis of variance (ANOVA) on the willingness to join a team with the number of defectors as the within-subjects factor and the previous outcome of the participant as the between-subjects factor
In the context of prisoner’s dilemmas [19] or public goods games [24, 40], previous studies found that introducing strategies that refuse playing with defectors opens space for cooperative strategies to invade the previously stable defective equilibria
Summary
Cooperation between self-interested agents has been a fundamental research topic in economics [20] and evolutionary biology [41]. Similar non-linear profiles have been found in whale hunting by humans [2] and in international relations [33] This situation may occur in voluntary vaccination [79]—where a certain fraction of individuals need to vaccinate for a population to achieve herd immunity—or simple daily tasks whose completion requires the effort of a minimum number of group members—such as college or company team projects. Reducing greenhouse gas emissions stands as a costly action that, if done by a sufficient number of countries, allows preventing catastrophic outcomes and benefits everyone This situation inspired the so-called collective risk dilemma (CRD) [6, 37, 53, 71, 77]. Everyone loses the saved endowment with a given probability (therein lies the risk)
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