Towards a Formal Analysis of Emotions in Games

Rational choices depend on emotions. It is often said that human players tend in many situations to act irrationally (see, for example [3]). What is meant by the phrase "the player acted irrationally" is that at the time of the decision the player was aware of another possible choice, which he preferred over the one he actually chose. Implicit in the latter is an assumption that the player has a preference order over the set possible choices that he is aware of. Of course, the meaning of preference is immediately contradicted by the "irrational" choice. Thus, definitions of rationality tend to be circular. We prefer here to view all players as rational and assume that what may seem to an observer to be an irrational choice may be in the final account the most preferred choice from the decision maker's viewpoint. The factors that affect the choice include various emotions associated with different actions and state, and lack of information or inability to adequately analyze the decision problem. In this paper we focus on such emotional aspects. The decision maker chooses actions depending on his own emotional state and what he believes the emotional states might be in the future, depending on the choices he might make. Thus, when a player has to form his preferences or to understand the emotions of other players in the game, he needs to understand the emotions that may arise in various situations in the game. In nontechnical speech, emotional decisions may seem to be the antithesis of rational ones. However, in the analysis of games, what matters are the preferences of players, regardless of whether or not they are formed based on a quantitative analysis or on spontaneous emotions. To understand the preferences, we have to understand the emotions that affect them. In [4] we argued that in many situations strategic analysis and formation of preferences are intertwined.