The Persistent Power of Promises

This paper investigates how the passage of time affects trust, trustworthiness, and cooperation. We use a hybrid lab and online experiment to provide the first evidence for the persistent power of communication. Even when 3 weeks pass between messages and actual choices, communication raises cooperation, trust, and trustworthiness by about 50 percent. Lags between the beginning of the interaction and the time to respond do not substantially alter trust or trustworthiness. Our results further suggest that the findings of the large experimental literature on trust that focuses on laboratory scenarios in which subjects are forced to choose their actions immediately after communicating, may translate to more ecologically valid settings in which individuals choose actions outside the lab and long after they initially made promises.