Promising serves as an important commitment mechanism by operating on a potential cheater’s internal value system. We present experimental evidence on what motivates people to keep their promises. First, they feel that they are duty-bound to keep their promises regardless of whether promisees...

We investigate why people keep their promises in the absence of external enforcement mechanisms and reputational effects. In a controlled laboratory experiment we show that exogenous variation of second-order expectations (promisors' expectations about promisees' expectations) leads to a...