Humans may be less inclined to punish bad behaviour than previous studies have suggested.

Michael McCullough of the University of Miami in Florida and his colleagues used computer-controlled games to look for evidence of altruistic punishment, in which an individual receives no clear benefit for inflicting punishment but does so anyway.

Although those who were treated unfairly in one game did punish transgressors in the next, the witnesses of the unfairness did not. In fact, witnesses were more likely to display envy of gains by others than outrage at victims' losses. The authors suggest that experiments to identify altruistic punishment are vulnerable to multiple artefacts, such as errors made by humans in predicting how they would react to hypothetical situations.

Proc. R. Soc. B 280, 20122723 (2013)