Reciprocity Bias

In social psychology, reciprocity is the social norm of responding to an action taken by another person with a similar or equivalent action of one's own, typically rewarding positive actions and punishing negative ones; as a social construct, it means people generally become nicer and more cooperative in response to friendly actions, a pattern reinforced across society by a shared expectation of mutual exchange. Though not an innate human quality, reciprocity is learned and reinforced through repeated social interaction, and while it can appear to run against the predicted logic of pure self-interest, its prevalence gives it a real role in the decision-making of self-interested and other-interested people alike; this phenomenon is sometimes referred to as reciprocity bias, meaning a preference to reciprocate social actions.