An embarrassment of riches: modeling social preferences in ultimatum games

Experimental results in Ultimatum, Trust and Social Dilemma games have been interpreted as showing that individuals are, by and large, not driven by selfish motives. But we do not need experiments to know that. In our view, what the experiments show is that the typical economic auxiliary hypothesis of non-tuism should not be generalized to other contexts. Indeed, we know that when the experimental situation is framed as a market interaction, participants will be more inclined to keep more money, share less, and disregard other participants’ welfare [Hoffman et al., 1994]. When the same game is framed as a fair division one, participants overall show a much greater concern for the other parties’ interests. The data thus indicate that the context of an interaction is of paramount importance in eliciting different motives. The challenge then is to model utility functions that are general enough to subsume a variety of motives and specific enough to allow for meaningful, interesting predictions to be made. For the sake of simplicity (and brevity), in what follows we will concentrate upon the results of experiments that show what appears to be individuals’ disposition to behave in a fair manner in a variety of circumstances [Camerer, 2003]., though what we are saying can be easily applied to other research areas. Such experimental results have been variously interpreted, each interpretation being accompanied by a specific utility function. We shall consider three such functions and the underlying interpretations that support them, and assess each one on the basis of what they claim to be able to explain and predict.