Carrots without Bite: On the Ineffectiveness of 'Rewards' in sustaining Cooperation in Social Dilemmas

Peer-to-peer sanctions increase cooperation in multi-person social dilemmas (Fehr & Gachter (2000)), but not when subjects have the option to retaliate (Nikiforakis (2008)). One-shot peer-to-peer rewards have been found to enhance efficiency too (Vyrastekova & van Soest (2008), Rand et al. (2009a)), but it is an open question whether the positive impact on cooperation is weakened or strengthened when we allow for counterrewarding. We examine the impact of possible reciprocity in rewarding on cooperation in a non-linear public bad game, and find that efficiency in the social dilemma is equally low as absent any reward options. We hypothesize that subjects are unwilling to sever mutually profitable bilateral exchanges of reward tokens to induce cooperation in the social dilemma, and identify the underlying mechanism by comparing behavior across three matching protocols.