Rusbult's Investment Model of Relationships (1980)

• Rusbult's Investment Model of Relationships is an extension of SET, as it was noted that some people stay in relationships even when they aren't in profit. So, there must be another factor involved, which Rusbult stated was level of investment.
• Investment Models sees commitment as the key factor in relationship stability & Rusbult identified 3 factors in determining commitment (desire to persist with relationships):

  1. Satisfaction- based on comparison levels (high benefits- attention & sex) & low costs (arguments) = high commitment.
  2. Quality of alternatives- refers to whether the individual thinks their needs might be better fulfilled outside of the relationship (may be a different partner or being single). Low alternatives = high commitment.
• Investment Models sees commitment as the key factor in relationship stability & Rusbult identified 3 factors in determining commitment (desire to persist with relationships):

  3. Investment size- measure of all resources attached to the relationship & could be lost/ damaged if relationship ended. Tangible (house, money) or intangible (happy memories). High investment = high commitment.
• Maintenance mechanisms identified by Rusbult et al:

  • Accommodation- acting in a way that promotes relationships, rather than keeping a tally of costs & rewards.
  • Willingness to Sacrifice- putting partners' interests first.
  • Forgiveness- willingness to forgive partners' mistakes, both minor & serious ones.
• Le & Agnew 2003 Study:

  • Carried out a meta-analysis of 52 studies conducted between the late 1970's & the late 1990's. Each of these studies had explored different components of the Investment Model & the relation between them.
  • This produced a total sample of over 11,000 PPs (54% male & 46% female) from 5 countries cross-cultural & longitudinal (20 years).
• Le & Agnew 2003 Study findings:

  • Across all studies, satisfaction level, quality of alternatives & investment size were highly correlated with relationship commitment.
  • The correlation between satisfaction level & commitment was found to be significantly stronger than either quality or alternatives & investment size & commitment.
• Evaluation of Investment Model- strength:

  • Research support for the Investment Model from Le & Agnew, as it supports the link between all factors of Investment Model & the likelihood it will continue or end.
  • This supports the model's claims about the factors contributing to commitment- therefore increases the reliability of the model.
• Evaluation of Investment Model- strength:

  • Has real-world application: explaining abusive relationships- the model highlights features of the relationship that would explain why a victim of abuse might remain in a relationship.
  • They might lack alternatives or may have too much invested in the relationship to leave without significant cost.
  • Rusbult & Martz (1995) found victims of domestic abuse stayed committed to their partner under these circumstances.
  • Provides support for the model & may indicate the basis for interventions with victims of DA, which SET & Equity Theory can't account for.
• Evaluation of Investment Model- weakness:

  • Methodological issues with supportive studies- studies are mainly correlational, so cannot determine casuality & do not link to actual behaviours.
  • Studies mainly use questionnaires & interviews which are known to be subjective & unreliable.
  • Indicates that support for the model is not scientifically rigorous, which compromises its predictive validity.
• Evaluation of Investment Model- strength:

  • The Investment Model as an explanation of relationship maintenance is also shown to be valid for different sub-groups, such as friendships, homosexual relationships & cohabiting couples etc.
  • This suggests the universality of the Investment Model, making it applicable to a wide range of relationships.