Reciprocity (social psychology)
Reciprocity in social psychology refers to responding to a positive action with another positive action, rewarding kind actions. As a social construct, reciprocity means that in response to friendly actions, people are frequently much nicer and much more cooperative than predicted by the self-interest model; conversely, in response to hostile actions they are frequently much more nasty and even brutal.
Reciprocity as a behavior 
People categorize an action as kind by viewing its consequences and also by the person's fundamental intentions. Even if the consequences are the same, underlying intentions can cause an action to be reciprocated differently. Reciprocity is considered as a strong determining factor of human behavior. Positive reciprocal actions differ from altruistic actions as the former only follow from other positive actions and they differ from social gift giving in that those are not actions taken with the hope or expectation of future positive responses. The focus of reciprocity is centered more on trading favors than making a negotiation or a contract with another person. With reciprocity, a small favor can produce a sense of obligation to a larger return favor. This feeling of obligation allows an action to be reciprocated with another action. Because there is a sense of future obligation with reciprocity it can help to develop and continue relationships with people. Reciprocity works because from a young age people are taught to return favors and to disregard this teaching will lead to the social stigma of being an ingrate.
Reciprocity as a form of social obligation calling for future acts kindness can be seen in the Japanese word for thank you, "sumimasen," which means "this will not end" It is also presented in the Bulgarian word for thank you "Благо-даря" (blago-dariya), which means "Good I'll Give".
Positive and negative reciprocity 
Cooperative reciprocal tendencies i.e. inclinations to give back in a cooperative manner, are called positive reciprocity. On the other hand, retaliatory aspects i.e. the aspects of trying to get back and cause harm, are known as negative reciprocity. Unlike "cooperative" or "retaliatory" behavior in repeated interactions, reciprocity is an in-kind response to beneficial or harmful acts with no material gains expected by the actor.
Some examples of positive reciprocity include smiling waitresses getting tipped much more than less friendly ones (Tidd and Lochard, 1978), calls for contributions to charities being accompanied by small gifts, use of free samples of a certain product in a supermarkets (Cialdini, 1993).
Dennis Regan's experiment on returning a favor 
Reciprocal actions are important to social psychology as they can help explain the maintenance of social norms. Reciprocity is so strong that a person will feel obligated to return a favor regardless of whether they like the person who originally gave the favor and even if they did not want the favor, as was demonstrated in an experiment by Dennis Regan in 1971. Regan had subjects believe they were in an “art appreciation” experiment with a partner, who was really Regan’s assistant. In the experiment the assistant would disappear for a two-minute break and bring back a soft drink for the subject. After the art experiment was through, the assistant asked the subject to buy raffle tickets from him. In the control group the assistant behaved in exactly the same manner, but did not buy the subject a drink. The subjects who had received the favor, a soft drink, bought more raffle tickets than those in the control group despite the fact that they hadn’t asked for the drink to begin with. Regan also had the subjects fill out surveys after they finished the experiment and found that whether they personally liked the assistant or not had no effect on how many tickets they bought. One problem of reciprocity, however, focuses on the unequal profit obtained from the concept of reciprocal concessions. The emotional burden to repay bothers some more than others, causing some to overcompensate with more than what was given originally. In the Regan study, subjects paid more money for the tickets than the cost of the (un-requested) soft drink.
Public good experiments 
In public good experiments, behavioral economists have demonstrated that the potential for reciprocal actions by players increases the rate of contribution to the public good, providing evidence for the importance of reciprocity in social situations.
It may be a motivation for returning favors from others. A form of reciprocity is "reciprocal concessions," in which the requester lowers his/her initial request, making the respondent more likely to agree to a second request. The respondent agrees because the requester has lowered his/her request, making a concession to the respondent. The respondent then experiences the social obligation to make a concession in kind back to the requester, and thus agrees to the second, lower request. An example provided by Robert Cialdini in Influence: Science and Practice is a young boy asking Cialdini to purchase circus tickets (the initial request). When Cialdini declined, the boy lowered or "conceded" his request to merely buying some candy bars. Cialdini, seeing that the boy has made a concession, feels obligated to "return the favor" (reciprocate) and agrees to this second request.
See also 
- Reciprocity (cultural anthropology)
- Reciprocity (social and political philosophy)
- Reciprocity (international relations)
- Influence: Science and Practice
- Fehr, Ernst; and Simon Gächter (Summer 2000). "Fairness and Retaliation: The Economics of Reciprocity". Journal of Economic Perspectives 14 (3): 159–181. doi:10.1257/jep.14.3.159. ISSN 0895-3309.
- Armin Falk & Urs Fischbacher (February 2006). "A theory of reciprocity". Games and Economic Behavior 54 (2): 293–315. doi:10.1016/j.geb.2005.03.001.
- Cialdini, R.B. Influence: Science and Practice, 5th ed. Boston: Pearson.
- Regan, R. T. (1971). "Effects of a favor and liking on compliance". Journal of Experimental Social Psychology 7: 627–639. doi:10.1016/0022-1031(71)90025-4.
- Cialdini, R.B., Vincent, J.E., Lewis, S.K., Catalan, J., Wheeler, D. & Darby, B.L. (1975). "Reciprocal concessions procedure for inducing compliance: The door-in-the-face technique". Journal of Personality and Social Psychology 31 (2): 206–215. doi:10.1037/h0076284.