Optimal Individual Decisions with a Psycho-materialistic Utility Function

This paper proposes a theoretical model aimed at interpreting the outcome of some games. It is often observed that players do not play the Nash equilibrium, when their utility is modelled on their payoff only. However, other models which include psychological variables fail to describe the behaviours observed. Here I propose a utility function which encompasses both monetary and psychological payoffs in such a way that the predictions fit the actual decisions of the players observed in experiments.