Imitating emotions instead of strategies in spatial games elevates social welfare

The success of imitation as an evolutionary driving force in spatial games has often been questioned, especially for social dilemmas such as the snowdrift game, where the most profitable may be the mixed phase sustaining both the cooperative as well as the defective strategy. Here we reexamine this assumption by investigating the evolution of cooperation in spatial social dilemma games, where instead of pure strategies players can adopt emotional profiles of their neighbors. For simplicity, the emotional profile of each player is determined by two pivotal factors only, namely how it behaves towards less and how towards more successful neighbors. We find that imitating emotions such as goodwill and envy instead of pure strategies from the more successful players reestablishes imitation as a tour de force for resolving social dilemmas on structured populations without any additional assumptions or strategic complexity.