Filter theory:

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  • Support from Kerckhoff and Davis's
  • Conducted a longitudinal study in which both partners in dating couples completed questionnaires to assess two factors similarity of attitudes/values and complementarity of needs
  • Relationship closeness measured by another questionnaire 7 months later
  • Found closeness was associated with similarity of values but only for couples who had been together less than 18 months
  • Couples in longer relationships complementarity of needs predicted closeness

  Similarity is important in early stages of a relationship but complementarity is more important later on
• COUNTERPOINT:

  • Levinger pointed out that many studies have failed to replicate the original findings of Kerckhoff and Davis
  • He put this down to social changes over time (e.g. dating patterns) and to problems in defining the depth of a relationship in terms of its length
  • Kerckhoff and Davis chose an 18-month cut-off point to distinguish between short-term and long-term relationships assumed that partners who had been together longer than this were more committed and had a deeper relationship

  Questionable assumption means that it is undermined by the lack of validity of its evidence base
• LIMITATION:

  • Complementarity may not be central to all longer-term relationships
  • A prediction of filter theory is that in the most satisfying relationships partners are complementary, ie one partner may have a need to be dominant and the other a need to be submissive

  However, Markey et al found that lesbian couples of equal dominance were the most satisfied

  Their sample of couples had been romantically involved for a mean time of more than 4½ years.

  This suggests that similarity of needs rather than complementarity may be associated with long-term satisfaction, at least in some couples.