Prospect theory is the main behavioral alternative to expected utility. Tversky and Kahnemann (1992) motivate the utility function for gains and losses under prospect theory by using the axiom of preference homogeneity. However, they do not provide the formal proof. We provide the relevant...

We show that preference-homogeneity and loss-aversion are necessary and sufficient for the value function to have the power form with identical powers for gains and losses and for the probability weighting functions for gains and losses to be identical.