Pablo Brañas-Garza describes intriguing findings on punishment behaviors in individuals. Punishment is the infliction of a penalty in retribution for an offense, that can occur at the public, private, institutional or individual levels. In individual punishment, this imposition occurs in random encounters, under the rational caveat that: in order to punish someone, a cost must always be paid. In a social setting, he explains, subjects entitled with a sense of social identity are willing to pay this cost. Punishment, then, becomes a behavior that encourages cooperation among individuals.

Brañas-Garza employs data from 5 real experiments to explore whether subjects punish and anticipate others’ punishment. He concludes that, even in artificial environments, people punish very often, and not always rationally. Punishing behaviours vary according to changes in environment, time availability, efficiency issues, and subjects’ patience levels and willingness to cooperate. As Brañas-Garza suggests, punishment may be a means to coordinate individuals in societies, with careful consideration of the risk of unintended effects.