We introduce a simple two-stage game of endogenous network formation and information sharing for reasoning about the optimal design of social networks like Facebook or Google. We distinguish between unilateral and bilateral connections and between targeted and collective information sharing....

We experimentally study settings where an individual may have an incentive to adopt negative beliefs about another's intentions in order to justify egoistic behavior. Our first study uses a game in which a player can take money from an opponent in order to prevent the opponent from subsequently...