Investment Model of Relationships

• Rusbult's Investment Model:

  Developed to understand why people persist in some romantic relationships but not others. Relationships persist not just because of positive qualities which attract partners, but due to ties that bind partners to each other (their investment) and the absence of a better option (lack of alternatives). These factors provide an explanatory framework which predicts the chances of someone remaining committed.
• Commitment-

  The likelihood that an individual will persist with their current relationship; this is the product of their high satisfaction and investment into the relationship, and a low quality of alternatives.
• Satisfaction Level:

  Refers to the positive versus negative emotions experienced within a relationship and is influenced by the extent to which the other person fulfils the individuals most important needs. E.g. a partner may feel satisfied to the degree to which their partner gratifies their domestic, compassionate, and sexual needs.
• Quality of Alternatives:

  Referring to the extent to which an individual's most important needs might be filled outside of their current relationship. Perceiving that an attractive alternate may provide superior outcomes to those currently experienced may lead individuals away from their current relationship. However, if alternates aren't present, an individual might persist due to a lack of options. Attractive alternates aren't always other people- some people may see having no relationship as a better alternative.
• Investment Size:

  Rusbult proposed that investment size contributes to relationship stability. This is a measure of all resources attached to the relationship, and which would diminish in value or be completely lost if the relationship were to end. Partners make these investments (e.g. time and energy, friends, shared possessions) expecting that it provides a strong foundation for a long lasting future. Investments increase dependence on relationships as they increase connections which are costly to break- meaning they create a powerful psychological inducement to persist.
• Commitment Level:

  Referring to the likelihood that an involvement will persist. Commitment is high in romantic partners who are satisfied and expect little gain and high loss if they were to leave. Conversely, commitment is low when satisfaction levels and investments are both low, and the quality of alternatives is high. When people are satisfied and feel tied to their investments without any suitable alternatives, they become dependent on that relationship. Meaning that commitment is a consequence of increasing dependence.
• Key Study: Le and Agnew

  Procedure- Carried out a meta-analysis of 52 studies conducted between the late 70s and 90s, each exploring the different components of the investment model and the relation between them. The sample was then over 11,000 (54% male and 46% female) from 5 countries- USA, UK, Netherlands, Israel and Taiwan.
• Key Study: Le and Agnew

  Findings- across all studies, satisfaction level, quality of alternatives, and investment size were highly correlated with relationship commitment. The correlation between satisfaction level and commitment (.68) was significantly stronger than quality of alternatives (-.48) and investment size (.47) and commitment. The correlation between commitment and stay or leave behaviours were also significant (.47), with individuals showing higher levels of commitment and being more likely to stay than those with lower levels being more likely to leave.
• AO3: Research Support for the Investment Model

  Importance of commitment as an indicator of relationship stability is supported by Le et al's meta-analysis, analysing data from 38,000 p's in 137 studies over a 33 year period to discover key variables that predicted 'staying or leaving' behaviours in non-marital relationships. Commitment was a strong predictor of whether a relationship would persist. Other related variables which make up the investment model were modest predictors of staying in a relationship or breaking up (satisfaction, QoA, investments).
• AO3: Problems Measuring Variables

  Rusbult et al developed the 'Investment Model Scale' to overcome the issue. Showing this scale to be high in reliability and validity in the measurements of each variable, and it has been suitable for a wide variety of populations. Though an issue with this scale is that it relies on self-report measures which often have problems with responder bias. Though it is then extremely difficult to measure a subjective state like commitment in an alternative way.
• AO3: Real-Wold Application; Explaining Abusive Relationships

  It can explain why people persist; victims experience low satisfaction which would lead us to predict that they would leave, yet many stay. This model highlights features that explain why the victims remain. They may lack alternatives or be too much invested into that partner- this then makes dissolution too costly. Rusbult and Martz revealed that alternatives and investments were a strong indication of whether battered women at a shelter remained committed to and returned to their partner.
• AO3: Investment in the Future is Important

  Goodfriend and Agnew elaborated on the original model, including any plans that partners have made regarding the future of their relationship into 'investments'. Ending the relationship would mean that they lose the investments made to date, and the possibility of achieving any future plans made with the partner. Claiming that some relationships persist, not because of the current balance of investments, but the motivation of seeing these plans manifest. Their research provided evidence that future plans were strongly predictive of commitment.
• AO3: Wide Application of the Investment Model

  A strength is that its main claims (that commitment is positively correlated with satisfaction and investment levels) has been shown to be true across many populations and different types of relationships. Research has supported the relevance of the IM across many different cultures (US, Netherlands, Taiwan, etc) and different participant populations (martial, non-marital, homosexual, friends, and abusive relationships). IDA- Cultural Bias reduced
• AO3: Issues and Debates

  Nature Vs Nurture- the fact that evidence for the IM is found across many cultures may suggest that the human need for investment and commitment to relationships developed through the process of natural selection to help people to survive and reproduce. E.g. parents who are committed and invest into their relationship have a higher chance of ensuring their children's survival and passing on their genes. Meaning it supports the nature side of the debate.