Linguistics

Philosophy

Stochastic game

Materials science

Social psychology

Theoretical computer science

Reciprocity (cultural anthropology)

Range (aeronautics)

Reciprocal

Computer science

Computer network

Psychology

Mathematics

Asynchronous communication

Reciprocal altruism

Nash equilibrium

Composite material

Mathematical economics

Alternation (linguistics)

Nature Communications

In repeated social interactions, individuals often employ reciprocal strategies to maintain cooperation. To explore the emergence of reciprocity, many theoretical models assume synchronized decision making. In each round, individuals decide simultaneously whether to cooperate or not. Yet many manifestations of reciprocity in nature are asynchronous. Individuals provide help at one time and receive help at another. Here, we explore such alternating games in which players take turns. We mathematically characterize all Nash equilibria among memory-one strategies. Moreover, we use evolutionary simulations to explore various model extensions, exploring the effect of discounted games, irregular alternation patterns, and higher memory. In all cases, we observe that mutual cooperation still evolves for a wide range of parameter values. However, compared to simultaneous games, alternating games require different strategies to maintain cooperation in noisy environments. Moreover, none of the respective strategies are evolutionarily stable.

Cooperation in alternating interactions with memory constraints