In public good games, voluntary contributions tend to start off high and decline as the game is repeated. If high contributors are matched, however, contributions tend to stay high. We propose a formalization predicting that high contributors will self-select into groups committed to charitable...

Policies and explicit private incentives designed for self-regarding individuals sometimes are less effective or even counterproductive when they diminish altruism, ethical norms and other social preferences. Evidence from 51 experimental studies indicates that this crowding out effect is...