Group size and cooperation among strangers

Group Size and Cooperation among Strangers ∗

We study how group size a ects cooperation in an in nitely repeated n-player Prisoner's Dilemma (PD) game. In each repetition of the game, groups of size n ≤ M are randomly and anonymously matched from a xed population of size M to play the n-player PD stage game. We provide conditions for which the contagious strategy (Kandori, 1992) sustains a social norm of cooperation among allM players. Ou...

Binding Promises and Cooperation Among Strangers

Cooperation among strangers with limited information about reputation

The amount of institutional intervention necessary to secure efficiency-enhancing cooperation in markets and organizations, in circumstances where interactions take place among essentially strangers, depends critically on the amount of information informal reputation mechanisms need transmit. Models based on subgame perfection find that the information necessary to support cooperation is recurs...

Cooperation among strangers under the shadow of the future

We study the emergence of norms of cooperation in experimental economies populated by strangers interacting indefinitely. Can these economies achieve full efficiency even without formal enforcement institutions? Which institutions for monitoring and enforcement facilitate cooperation? Finally, what classes of strategies do subjects employ? We find that, first, cooperation can be sustained even ...

Synergy and group size in microbial cooperation.

Microbes produce many molecules that are important for their growth and development, and the exploitation of these secretions by nonproducers has recently become an important paradigm in microbial social evolution. Although the production of these public-goods molecules has been studied intensely, little is known of how the benefits accrued and the costs incurred depend on the quantity of publi...