Human utility embodies a number of seemingly irrational aspects. The leading example in this paper is that utilities often depend on the presence of salient unchosen alternatives. Our focus is to understand <i>why</i> an evolutionary process might optimally lead to such seemingly dysfunctional features...

In a two-stage extensive form game where followers can observe moves by leaders only with noise, pure subgame perfect Nash equilibria of the limiting game without noise may not survive arbitrarily small noise. Still, for generic games, there is always at least one subgame perfect equilibrium...