Two-speed evolution of strategies and preferences in symmetric games

Agents in a large population are randomly matched to play a material payoff game. They may have preferences that are different from the material payoffs. Agents learn equilibrium strategies according to their preferences before evolution changes the preference distribution in the population according to fitness. When agents know the preferences of the opponent in a match, only efficient symmetric strategy profiles of the material payoff game can be stable. When agents do not know the preferences of the opponent, only Nash equilibria of the material payoff game can be stable. For 2x2 symmetric games I characterize preferences that are stable