We use a lab experiment to investigate how providing the responder with options to reward and/or punish the proposer postacceptance affects behavior in ultimatum bargaining. We find that the presence of costly reward and punishment options affects behavior of both bargaining parties, even if those instruments are rarely used. Proposers are most generous when responders can both reward and punish, and offer least (even compared to the baseline) when responders can only reward. The likelihood of acceptance by responders, conditional on offer size, increases. The least generous offers have the highest chance of being accepted in the presence of punishment alone, even when punishment is not applied. It appears that the availability of additional instruments changes subjects' perception of the distribution of bargaining power and shifts fairness norms. The results have implications for optimal contract design in posted offer settings, such as decentralized online marketplaces for various tasks.
| INTRODUCTIONAn integral question of many economic studies is how an allocation mechanism can be augmented to improve its performance in terms of efficiency or welfare of some participants. Of particular interest in this regard are augmentations that employ decentralized, self-governing instruments. Rewards and punishments are arguably the oldest and most commonly used instruments of incentive provision. Besides rewarding desirable and sanctioning undesirable actions by changing payoffs, they have other possible functions, including feedback and emotional expression (see, e.g., Brandts & Cooper, 2007;Casari & Luini, 2009;Xiao & Houser, 2005). Previous studies investigated the effect of rewards or/and punishments on behavior in different contexts, 1 with the general result that they are, to various degrees, effective in promoting cooperation and efficiency. 2 In this paper, we use a laboratory experiment to investigate the behavioral incentives provided by the presence of reward and punishment options in a simple asymmetric bilateral bargaining setting of the ultimatum game (Güth et al., 1982). Despite its simplicity, this setting can serve as a prototype of many economic and social processes leading to allocation of resources. Examples include decisions to collaborate on a project, accept a job offer, merge with another business, or join a club. Bargaining positions are often asymmetric, with one party having more say in setting the terms of the deal. However, even in the most asymmetric cases where the terms are determined entirely by one party, the deal still hinges on a decision of voluntary engagement from the other party, for example, to accept a nonnegotiable job offer, business acquisition, or price in a store.As a specific example, consider an employer who makes a job offer to a candidate, either in a formal organizational setting or in a spot labor market, for example, for contractors. 3 The candidate may reject the offer, in which case the