This paper studies how imposing norms on contribution behavior affects individuals' intrinsic motivation. We consider … legally a tax. We design a randomized field experiment with treatments informing individuals that the levy is a tax. We …, communicating the legal norm results in a significant crowd-out of intrinsic motivation. In contrast, strongly intrinsically …

. This raises a question of how the lottery incentive interacts with social preferences. We present an experiment in which we …

-interest, providing strong evidence for pocketbook voting. However, social preferences like altruism, public good considerations and …

strongly influence participation and voting. However, social or expressive motives, such as stated altruism, environmental …

counterproductive when they diminish altruism, ethical norms and other social preferences. Evidence from 51 experimental studies …