Models of evolutionary game theory have shown that punishment may be an adaptive behaviour in environments characterised by a social-dilemma situation. Experimental evidence closely corresponds to this nding but questions the cooperation-enhancing eect of punishment if players are allowed to...

In intergroup contests a manager advises and motivates her group's members. Her rewards often depend on the subsequent contest expenditure of the members. I test whether such incentives undermine the credibility and effectiveness of a manager's efforts. In the different experimental treatments...