In a 1-year randomized controlled trial involving thousands of university students, we provide real-time private feedback on relative performance in a semester-long online assignment. Within this setup, our experimental design cleanly identifies the behavioral response to rank incentives (i.e.,...

One of the key scientific challenges is the puzzle of human cooperation. Why do people cooperate? Why do people help strangers, even sometimes at a major cost to themselves? Why do people want to punish people who violate norms and undermine collective interests? This book is inspired by the...