Relationships in Psychology

Choosing a partner: evolution and attraction

Sexual selection means traits that help an animal get a mate get passed on. There are two kinds.

• Intra-sexual selection: members of one sex (often males) compete with each other. Traits like size or status win.
• Inter-sexual selection: one sex (often females) chooses carefully. Females invest more in each child (pregnancy, feeding), so a poor choice costs more. They may prefer partners with resources and willingness to care.

A survey of over 10,000 people in 37 cultures found men tended to value youth and looks more, and women valued resources more. Evaluation: it fits many findings, but culture, women's education and same-sex relationships are hard to explain with genes alone.

Self-disclosure means telling someone personal things about yourself. It grows in breadth (more topics) and then depth (more private things). It should be gradual and two-way (reciprocal).

Physical attractiveness matters too. Symmetrical faces are often rated attractive. The halo effect means good-looking people are also assumed to be kind or clever. The matching hypothesis says we pick partners of similar attractiveness, so we are less likely to be rejected.

Filter theory says we narrow down partners in three stages: (1) social demography: location, class, education, religion; (2) similarity in attitudes: shared values matter early; (3) complementarity of needs: in longer relationships, needs that fit together matter.

Why people stay: exchange, equity and investment

Social exchange theory sees a relationship like a trade. Rewards (care, fun, support) minus costs (time, stress) = profit. We also use a comparison level (CL): what we think we deserve, from past relationships and the media, and a comparison level for alternatives (CLalt): could someone else be better? It has stages: sampling, bargaining, commitment, institutionalisation.

Equity theory says what matters is fairness, not profit. If one partner gives a lot and gets little, they feel angry. The one who gets too much feels guilty. Partners may try to restore fairness, or change how they see things.

Rusbult's investment model says commitment depends on three things: satisfaction (rewards beat costs), quality of alternatives (few good alternatives = more commitment) and investment size (time, money, shared friends, children, future plans). Strong commitment leads to relationship maintenance such as forgiving, making sacrifices and ignoring tempting alternatives. This explains why some people stay even in unhappy, even abusive, relationships.

Evaluation: these theories are hard to test exactly (how do you measure a reward?), and many studies are correlational, so they show links, not causes.

How relationships end: Duck's phase model

Duck suggested that breakdown happens in phases, each starting at a threshold (a thought that pushes to the next phase):

1. Intra-psychic phase ('I can't stand this any more'): one partner thinks privately about their unhappiness.
2. Dyadic phase ('I'd be justified in leaving'): the couple talk it over. They may fix things, or not.
3. Social phase ('I mean it'): friends and family are told. People take sides; the split becomes public.
4. Grave-dressing phase ('It's now inevitable'): each person tells a story of the break-up that makes them look good and helps them move on.

A resurrection phase was added later: people grow and get ready for new relationships. Evaluation: it is useful for counsellors (help with communication in the dyadic phase), but it describes rather than explains why breakdown happens.

Virtual and parasocial relationships

Virtual relationships are formed or kept online (messages, social media). Two ideas compete: reduced cues theory (fewer face and voice cues make people less careful, sometimes ruder) and the hyperpersonal model (people can plan what they share, so they may disclose more and faster). Online there is less gating: features like looks or a stammer that might stop a first meeting are hidden.

Parasocial relationships are one-sided bonds with someone who does not know you, such as a film star, singer or influencer. The Celebrity Attitude Scale describes three levels: entertainment-social (chatting about them), intense-personal (strong personal feelings) and borderline-pathological (uncontrolled fantasies or behaviour). They may link to insecure attachment (absorption-addiction model: people seek identity and fulfilment, which can become addictive).

Try it

In the 3D, step 3, watch the commitment bar grow as each part is added. Then try at home: think of a friendship you value (not a romantic one). Score from 1 to 10 your satisfaction, how good your alternatives are, and how much you have invested. Which part keeps the friendship strongest?

Key formulas and definitions

• Key term: Sexual selection = traits that help get a mate are passed on (intra-sexual: compete; inter-sexual: choose)
• Key term: Self-disclosure = revealing personal information, growing in breadth then depth, reciprocally
• Key term: Matching hypothesis = choosing partners of similar attractiveness
• Key term: Filter theory = social demography → similarity of attitudes → complementarity of needs
• Formula idea: Profit = Rewards − Costs; compare with CL and CLalt
• Formula idea: Commitment = Satisfaction + (few) Alternatives + Investment
• Key term: Duck's phases = intra-psychic → dyadic → social → grave-dressing (→ resurrection)
• Key term: Parasocial relationship = one-sided bond with a celebrity or media figure

Worked examples

Common mistakes

• [object Object]
• [object Object]
• [object Object]
• [object Object]