Reciprocity in experimental economics encompasses the tendency of individuals to cooperate, punish unfair behavior, and reward fair behavior.

The Ultimatum Game is a classic reciprocity experiment where one player proposes a division of money with another player, who can either accept or reject the offer.

In the Ultimatum Game, proposers typically offer a split that is slightly unfair in their favor, but not excessively so.

In the Ultimatum Game, responders typically accept fair offers and reject unfair offers, even if it means they receive nothing.

The Nash Equilibrium in the Ultimatum Game is (99, 1), where the proposer offers $99 to the responder and keeps $1 for themselves.

The Ultimatum Game shows that people are willing to punish unfair behavior, even if it means they receive nothing themselves.

The Prisoner's Dilemma is a classic reciprocity experiment where two players can either cooperate or defect. If both players cooperate, they both receive a moderate payoff. If one player defects and the other cooperates, the defector receives a high payoff and the cooperator receives a low payoff. If both players defect, they both receive a low payoff.

The Nash Equilibrium in the Prisoner's Dilemma is (Defect, Defect), where both players defect and receive a low payoff.

The Prisoner's Dilemma shows that people are more likely to cooperate if they expect the other player to cooperate as well.

The Public Goods Game is a classic reciprocity experiment where players can contribute to a public good, which benefits all players equally. If all players contribute, they all receive a high payoff. If some players contribute and others do not, the contributors receive a lower payoff and the non-contributors receive a free ride.

The Nash Equilibrium in the Public Goods Game is (Do Not Contribute, Do Not Contribute), where no player contributes to the public good and all players receive a low payoff.

The Public Goods Game shows that people are more likely to contribute to a public good if they expect other players to contribute as well.

Reciprocity in experimental economics can be influenced by a variety of factors, including culture and norms, social identity, and trust.

Reciprocity can be used to promote cooperation in real-world settings by designing institutions that encourage reciprocity, educating people about the benefits of reciprocity, and creating social norms that support reciprocity.

There are a number of challenges to using reciprocity to promote cooperation in real-world settings, including self-interest, free riding, and enforcement problems.