aqa  Theories of romantic relationships: social exchange theory, equity theory and Rusbult’s investment model of commitment, satisfaction, comparison with alternatives and investment

Theory 1: Social Exchange Theory

Social Exchange Theory claims that, for the individual, the best result from a relationship is to make a profit. For this to occur, there must be a minimum cost and a maximum reward. The principles of operant conditioning apply to this theory, in that if something is rewarding, we are more likely to pursue it. Examples of rewards may include gaining a partner with good looks, money and loyalty. Costs may be spending time with a partner’s family, or less time with their own friends. Commitment to a relationship is dependent on the ‘profitability’ of this outcome.

Thibaut and Kelley’s (1959) four-stage model:

  1. SamplingThe couple explore the rewards and costs in a variety of relationships
  2. Bargaining The couple ‘costs out’ the relationship and identifies sources of profit and loss
  3. Commitment – The couple settles into a relationship; the exchange of rewards becomes relatively predictable
  4. Institutionalization –  The interactions are established; the couple have settled down 

Comparison Levels: Thibaut and Kelley introduced two comparison levels against which an existing relationship can be evaluated.

  • The comparison level is a comparison between the current relationship and what we are used to in the past, or believe is appropriate in the current relationship. If the current relationship compares favourably, the person is motivated to stay in the relationship.
  • The comparison level for alternatives. If a person feels they might have more positive outcomes with a new partner, they may end the current relationship.
Supporting Research

Simpson et al. (1990) investigated how people deal with the threat of potential alternatives. They asked participants to rate members of the opposite sex in terms of their physical attractiveness and found that those participants who were already in relationships gave lower ratings. This had the effect of lowering the perceived profits associated with a potential new partner and thus reducing any threat to the current relationship.

Issues & Debates


  • Abusive relationships: Rusbult and Martz (1995) argue that the principals of social exchange can be used to explain abusive relationships. When investments are high (e.g. children, financial security) and alternatives are relatively low (e.g. lack of money, house), that even an abusive relationship may be viewed as profitable.
  • Culture bias:  Moghaddam (1998) suggests that social exchange theory may only apply to Western cultures, where personal profit is more important and social mobility is high.


Theory 2: Equity Theory

This theory builds on Social Exchange Theory and states that fairness is more important than personal gain in maintaining a relationship. This is referred to as equity theory (Walster et al. 1978). Unlike Social Exchange, which states that individuals try to maximize their rewards and minimize their costs, equity theory holds that inequity (unfairness) in relationships is more likely to create dissatisfaction. This could work either way; being the giver or receiver in an unfair relationship.

The four underlying principles of equity theory:

  1. People try to maximize their rewards in a relationship.
  2. Trading rewards between both parties occurs to ensure fairness (e.g. paid back in favours).
  3. Inequity produces dissatisfaction, with the person who receives the lower level of reward (the ‘loser’) experiencing the most dissatisfaction.
  4. The loser will endeavor to rectify the situation, and the greater the perceived inequity, the greater the effort to remedy the situation.
Supporting Research
  • Stafford and Canary (2006). Asked over 200 couples to complete a questionnaire on equity an marital satisfaction. Satisfaction was highest for spouses who perceived their marriage to be equitable and lowest for partners who considered themselves particularly under-benefitting.
Issues & Debates


  • Gender Differences: Women more likely to have an extra-marital affair if relationship perceived to be inequitable and they are the ‘loser’. Extra-marital affairs for men more likely to be sexual in nature, and not linked to marital satisfaction (Atwater et al. 1985).
  • Too simplistic: Brandau-Brown (2007) suggests that relationships are more sophisticated than this theory suggests and the reason people stay together is more complex.
  • Cultural Differences:  Research does not support the view that equity is equally important in all cultures, and therefore the theory is biased. Aumer-Ryan et al. (2007) interviewed university students and found that Hawaiian sample (individualist) were happiest when relationship was perceived as equitable, but Jamaican sample (collectivist) were happiest when they perceived themselves to be over-benefitting. This was for both men and women in the Jamaican sample, where equity was less important.
  • Applications to marital therapy: Research (Larsson et al. 1998)has established that wives, compared to husbands, are more likely to feel distressed as a result of perceived inequality in their relationships. Inequity therefore needs to be addressed before marital therapy can make headway, as inequity causes intimacy (and therefore compatibility) issues for wives.