The norm of reciprocity is the expectation that people will respond favorably to each other by returning benefits for benefits, and responding with either indifference or hostility to harms. The social norm of reciprocity often takes different forms in different areas of social life, or in different societies. All of them, however, are distinct from related ideas such as gratitude, the Golden Rule, or mutual goodwill. See reciprocity (social and political philosophy) for an analysis of the concepts involved.
An underlying norm of reciprocity is by itself a powerful engine for motivating, creating, sustaining, and regulating the cooperative behavior required for self-sustaining social organizations, as well as for controlling the damage done by the unscrupulous. See the discussions in tit for tat and reciprocity (social psychology). The power and ubiquity of the norm of reciprocity can be used against the unwary, however, and is the basis for the success of many malicious confidence games. Minor, usually less malicious examples are techniques used in advertising and other propaganda whereby a small gift of some kind is proffered with the expectation of producing a desire on the part of the recipient to reciprocate in some way, for example by purchasing a product, making a donation, or becoming more receptive to a line of argument. These minor examples include gifts of stickers and pens distributed by charities and flowers handed out by members of the Hare Krishna group.
Two key elements of the norm of reciprocity are positive and negative aspects to the term.
A positive norm of reciprocity is "the embedded obligations created by exchanges of benefits or favours among individuals. The recipient feels indebted to the favour or benefit giver until he/she repays" (Chen, 2009). The positive reciprocity norm is a common social expectation where a person who helps another person can expect positive feedback whether it's in the form of a gift, a compliment, a loan, a job reference, etc. In social psychology, positive reciprocity refers to responding to a positive action with another positive action (rewarding kind actions). This norm is so powerful, it allows the initial giver to ask for something in return for what was given rather than having to wait for a voluntary reciprocal act. In some cases, a person does not have to ask for the other person to return a favour because it's already implied. Reciprocity also works at the level of liking; We like people who help us, and dislike those who ask for help but never return it. Disapproval is often enough to make people comply with norm of reciprocity.