We study experimentally the effect of expectations on whether trust is repaid. Subjects respond with untrustworthy behavior if they see that little is expected of them. This suggests that guilt aversion plays an important role in the repayment of trust.

This paper experimentally explores how the enforcement of cooperative behavior in a social dilemma is facilitated through institutional as well as emotional mechanisms. Recent studies emphasize the importance of anger and its role in motivating individuals to punish free riders. However, we find that anger also triggers retaliatory behavior by the punished individuals. This makes the enforcement of a cooperative norm more costly. We show that in addition to anger, "social" emotions like guilt need to be present for punishment to be an effective deterrent of uncooperative actions. They play a key role by subduing the desire of punished individuals to retaliate and by motivating them to behave more cooperatively in the future.

In public good provision, privileged groups enjoy the advantage that some of its members find it optimal to supply a positive amount of the public good. However, their inherent asymmetric nature may make the enforcement of cooperative behavior through informal sanctioning harder to accomplish. In this paper we experimentally investigate public good provision in normal and privileged groups with and without decentralized punishment. We find that compared to normal groups, privileged groups are relatively ineffective in using costly sanctions to increase everyone's contributions. Punishment is less targeted towards strong free-riders and they exhibit a weaker increase in contributions after being punished. Thus, we show that privileged groups are not as privileged as they initially seem.

This is an experimental study of negative reciprocity in the case of multiple reciprocators. We use a three-player power-to-take game where a proposer is matched with two responders. We compare a treatment in which responders are anonymous to each other (strangers) with one in which responders know each other from outside the lab (friends). We focus on the responders' decisions, beliefs, and emotions. Our main findings are (1) friends punish the proposer more than strangers, (2) friends are more likely to coordinate their punishment (without communication), and (3) both punishment and coordination are explained by the responders' emotional reactions.

There is a large body of literature documenting both a preference for immediacy and a tendency to procrastinate. O'Donoghue and Rabin (1999a,b, 2001) and Choi et al. (2005) model these behaviors as the two faces of the same phenomenon. In this paper, we use a combination of lab, field, and survey evidence to study whether these two types of behavior are indeed linked. To measure immediacy we had subjects choose between a series of smaller-sooner and larger-later rewards. Both rewards were paid with a check in order to control for transaction costs. To measure procrastination we use the subjects' actual behavior in cashing the check and completing tasks on time. Our results lend support to the hypothesis that subjects who have a preference for immediacy are indeed more likely to procrastinate.

We use a novel experimental design to distinguish strategic from non-strategic motives for cooperation in social dilemmas. By using the strategy method in a repeated sequential prisoners' dilemma with a known probabilistic end, we can differentiate between end-game and non-end-game behavior. Individuals that cooperate non-strategically do not change their behavior depending on whether the game continues or not. In contrast, strategically-motivated individuals cooperate only if the game continues and otherwise defect. Our design allows us to control for learning effects and beliefs concerning the cooperativeness of others. Results with two different subject pools indicate that the most common motive for cooperation is indeed strategic. Moreover, strategic motivations also explain most of the commonly-observed pattern of conditional cooperation.

This paper shows that there is a positive and statistically significant correlation between the short-term discount rate over a monetary reward and the short-term discount rate over a primary reward (chocolate). In particular, for subjects who like chocolate and are hungry. This suggests that monetary rewards are suitable for the study of inter-temporal choice. In fact, given the problems associated with the use of primary rewards (differing tastes for the good, hunger, and possible satiation), we argue that measurement with monetary rewards is more reliable.

In this paper, we study the effectiveness of intergroup competition in promoting cooperative behavior. We focus on intergroup competition that is non-rival in the sense that everyone can be a winner. This type of competition does not give groups an incentive to outcompete others. However, in spite of this fact, we find that intergroup competition produces a universal increase in cooperation. Furthermore, in settings where there are strong incentives to compete, intergroup competition benefits a majority of individuals.

This experimental study investigates how behavior changes after punishment for a selfish action. The focus is on how proposers in a power-to-take game adjust their behavior depending on their fairness perceptions, their experienced emotions, and their interaction with responders. We find that fairness plays an important role. Fair-minded proposers tend to feel less regret when they learn they could have taken more. Furthermore, proposers who take more than their perceived fairness norm feel more shame. This induces proposers to lower their claims. We also find that the perceived fairness norm varies considerably between individuals. Therefore, it is not the case that proposers who considered themselves fair are particularly nice to responders.