Dishonest helping and harming after (un)fair treatment

People experience fair and unfair treatment daily, and at times may react by breaking ethical rules and lying. Here, we assess the extent to which individuals engage in dishonest behavior aimed at helping or harming others after they experience (un)fair treatment. Across three financially incentivized experiments, recipients in a dictator game received a fair or unfair amount and then could, by means of dishonesty, inflate or deflate their counterparts’ pay. Results show that dishonest helping is a common and robust behavior. Individuals lie to help others after fair, unfair, and no prior treatment. Dishonest harming, however, is less prevalent. Only after unfair treatment, some, but not all, individuals engage in dishonest harming. Dishonest harming was associated with high levels of anger and disappointment, and low levels of gratitude. Interestingly, the source of (un)fairness, whether it is intentional or not, did not attenuate peoples’ behavior, suggesting that dishonest reactions to (un)fairness were driven by the mere (un)fair treatment, and not by a motivation to reciprocate an (un)fair counterpart.