This paper presents a formal theory of reciprocity. Reciprocity means that people reward kind actions and punish unkind …

In this paper we show that a simple model of fairness preferences explains major experimental regularities of common …

mechanism reliably supports the evolution of cooperation when actions vary continuously. Ambiguous reciprocity, a strategy … can stabilise cooperative strategies against the corrosive effect of ambiguous reciprocity. Evolved strategies often … consist of cooperative reciprocity with ingroup partners and uncooperative reciprocity with outgroup partners. Results from a …