  This study proposes a tractable stochastic choice model to identify
motivations for prosocial behavior, and to explore alternative motivations of
deliberate randomization beyond ex-ante fairness concerns. To represent social
preferences, we employ an additively perturbed utility model consisting of the
sum of expected utility and a nonlinear cost function, where the utility
function is purely selfish while the cost function depends on social
preferences. Using the cost function, we study stochastic choice patterns to
distinguish between stochastic inequity-averse behavior and stochastic
shame-mitigating behavior. Moreover, we discuss how our model can complement
recent experimental evidence of ex-post and ex-ante fairness concerns.
