  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.
