Equity theory is a theory about fairness. Its application to close relationships has been primarily advanced by Elaine Hatfield (previously known as Elaine Walster) and her colleagues in the book Equity: Theory and Research (Walster, Walster, and Berscheid 1978). The book outlines four interlocking propositions of equity theory and discusses the application of equity theory to different types of relationships, including intimate ones. The propositions are: 1. Individuals will try to maximize their outcomes (where outcomes equal rewards minus costs). 2a. Groups can maximize collective reward by evolving accepted systems for equitably apportioning resources among members. Thus, groups will evolve such systems of equity, and will attempt to induce members to accept and adhere to these systems. 2b. Groups will generally reward members who treat others equitably, and generally punish (increase the costs for) members who treat others inequitably. 3. When individuals find themselves participating in inequitable relationships, they become distressed. The more inequitable the relationship, the more distressed the individuals feel. 4. Individuals who discover they are in an inequitable relationship attempt to eliminate their distress by restoring equity. The greater the inequity that exists, the more distress they feel, and the harder they try to restore equity.
Equity theory rests on the assumption that people are self-interested and will try to maximize their personal gains. It has sometimes been questioned by researchers who believe that the nature of close relationships differs from other types of relationships. They argue that close relationships should not be based on individual calculations of costs and rewards and a self-interested
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