We study individuals who can choose how to compete with an opponent for one nonzero payoff. They can either nudge themselves into a fair set of rules where they have the same information and actions as their opponent, or into unfair rules where they spy, sabotage or fabricate their opponent's...

We study how defaults affect charitable donations. In a field experiment that was conducted on a large online platform for charitable giving, we exogenously vary the default options in the donation form in two distinct choice dimensions. The first pertains to the primary donation decision,...