Rusbult's investment model

• Rusbult’s Investment Model explains relationship commitment by expanding on Social Exchange Theory (SET). The model argues that commitment is influenced by three key factors:

  1. Satisfaction
  2. Comparison with alternatives (CLalt)
  3. Investment
• Satisfaction – The extent to which romantic partners feel the rewards of the relationship exceed the costs.
• Comparison with Alternatives (CLalt) – Whether an individual believes they could have a better relationship with someone else, which would bring more rewards and fewer costs, or no relationship at all.
• Investment – The resources put into the relationship that would be lost if the relationship ended. The two types are intrinsic and extrinsic investments.
• Intrinsic investments are resources directly put into the relationship. They can be tangibles or intangibles.

  • Tangibles = money, possessions etc.
  • Intangibles = time, energy, self-disclosures etc.
• According to Rusbult et al. (2011), commitment is strongest when satisfaction is high, alternatives are low, and investment is high. This explains why people may stay in unhappy relationships — they feel they have invested too much to leave.
• Commitment expresses itself in everyday relationship maintenance mechanisms. These include:

  • Accommodate their partner’s behaviour rather than retaliate.
  • Willingness to Sacrifice their own needs for the relationship and put their partner's interest first.
  • Forgive serious transgressions.
  • Develop positive illusions about their partner and ridicule alternatives to maintain commitment.
• A strength of the Investment Model is that research supports its claims. Le & Agnew (2003) conducted a meta-analysis of 52 studies with over 11,000 participants from 5 countries and found that satisfaction, comparison with alternatives, and investment all predicted commitment. This supports the model’s claim that these three factors influence relationship stability. Furthermore, these findings were consistent across cultures, genders, and different relationship types (e.g., homosexual and heterosexual relationships), increasing the model’s generalisability.
• A major strength is that the Investment Model explains why people stay in abusive relationships. Rusbult & Martz (1995) found that women in abusive relationships were more likely to stay if they had invested heavily (e.g., time, money, children) and had few alternatives. This supports the idea that commitment is influenced by investment rather than just satisfaction. The model is therefore useful in real-world applications, such as helping psychologists understand why individuals remain in toxic or abusive relationships.
• A limitation is that the model focuses on commitment rather than satisfaction. Rusbult et al. (2011) found that some individuals remain in unhappy relationships because of their investments, but this does not explain why they became dissatisfied in the first place. Other theories, such as Equity Theory, may provide a better explanation for why relationships deteriorate, rather than just why people stay in them. This suggests that the model is useful for explaining commitment but does not fully explain relationship satisfaction.
• A limitation is that it focuses only on past investments and ignores the importance of future plans in commitment. Goodfriend & Agnew (2008) argued that commitment is also influenced by future investments, such as shared goals (e.g., marriage, children, career plans). Their research suggests that individuals may stay in relationships not just because of past investments but because they have planned a future together. Therefore, the model may be oversimplified, as it fails to recognise the true complexity of investment, specifically how planning for the future influences commitment.
• Extrinsic investments are resources that previously did not feature in the relationship but are now linked to it, e.g., joint possessions, mutual friends, and shared memories.