investment model
a theory explaining commitment to a relationship in terms of one’s satisfaction with, alternatives to, and investments in the relationship. According to the model, commitment is a function of not only a comparison of the relationship to the individual’s expectations but also the quality of the best available alternative and the magnitude of the individual’s investment in the relationship; the investment of resources serves to increase commitment by increasing the costs of leaving the relationship. Although originally developed in the context of romantic associations and friendships and used to explain why people stay in abusive relationships, the investment model has since been extended to a variety of other areas, including employment and education. [proposed in 1980 by U.S. social psychologist Caryl E. Rusbult (1952–2010)]