Difficulty: Introductory to Intermediate | Prerequisites: Familiarity with basic social psychology concepts (e.g. attitudes, social cognition). No prior relationship-science background needed.
Attraction and close relationships sit at the heart of social psychology, connecting individual-level cognition (how we perceive and evaluate others) with broader interpersonal dynamics (how bonds form, deepen and sometimes dissolve). This material spans two main lecture blocks: Part 1 covers what draws people together in the first place (similarity, proximity, reciprocal liking, physical attractiveness), while Part 2 examines the theories that explain how relationships are maintained or end (interdependence, investment, equity), the different forms love can take, attachment styles, and cultural variation. You should already be comfortable with basic attribution theory and attitudes, since several studies here build on those ideas.
We are attracted to people who are similar to us, physically nearby, and who seem to like us back, and physical attractiveness exerts a powerful independent effect on liking. Once relationships form, their survival depends on the balance of rewards, costs, investment and perceived equity. Love itself comes in multiple forms (companionate vs. passionate; Sternberg's triangular model), attachment styles shape how we experience romance, and culture influences which kinds of love people value most.
Similarity (attraction principle)
The finding that people are more attracted to others who share their attitudes, values, demographics and activities. In simple terms, we gravitate towards people who think and live the way we do.
Proximity
Physical or functional closeness between people, which increases the likelihood of friendship and attraction. Think of it as: the nearer someone is in your daily life, the more likely you are to end up liking them.
Mere exposure effect
The tendency for repeated, unreinforced exposure to a stimulus (including a person) to increase liking for that stimulus. In simple terms, familiarity breeds fondness, not contempt.
Reciprocal liking
The phenomenon whereby knowing or believing that someone likes you increases your liking for them in return. Think of it as: liking is contagious.
"What is beautiful is good" effect
The stereotype that physically attractive people also possess desirable personality traits such as intelligence, social skill and happiness. In simple terms, we assume good-looking people have good lives.
Self-fulfilling prophecy (in attractiveness)
The process by which expectations about a person (e.g. that an attractive person is friendly) lead others to behave in ways that elicit the expected behaviour, confirming the original belief.
Averaging effect
The finding that composite (morphed) faces are rated as more attractive than individual faces, because irregularities are smoothed out.
Interdependence theory (Thibaut and Kelley)
A theory proposing that partners in close relationships undergo a transformation of motivation, shifting from pure self-interest to thinking of themselves as a unit. Think of it as: "her dreams are my dreams."
Investment model (Rusbult)
A model predicting that relationship commitment depends on satisfaction (rewards minus costs), the quality of available alternatives, and the size of one's investment in the relationship.
Social exchange theory
A framework suggesting that relationship satisfaction depends on the perception of rewards, costs, and how the outcome compares to what one feels entitled to and what alternatives offer.
Equity theory
The idea that people are most comfortable in relationships where both partners perceive a roughly equal ratio of costs to rewards. Both over-benefited and under-benefited partners feel uneasy.
Cohesiveness model (Levinger)
A model distinguishing two forces in relationships: attraction forces (tied to satisfaction) and barrier forces (e.g. children, finances) that discourage leaving.
Companionate love
Feelings of deep affection, trust and care for another person without intense passion or physiological arousal. Think of it as the warmth of a close, long-standing friendship.
Passionate love
An intense emotional state involving longing, physiological arousal, and a preoccupation with the other person. When reciprocated it brings fulfilment; when not, despair.
Triangular theory of love (Sternberg)
A theory proposing that love is composed of three ingredients: intimacy (closeness), passion (physical and emotional arousal), and commitment (the decision to stay).
Attachment style
A pattern of relating to romantic partners rooted in early caregiving experiences. The three main styles are secure, avoidant and anxious.
Fatal attraction
The idea that a quality that initially attracts you to someone (e.g. confidence that reads as possessiveness) can later become the source of relationship problems.
Similarity is one of the strongest predictors of interpersonal attraction. Sharing attitudes, values, demographic background or even something as trivial as a birthday is enough to increase liking and smooth social interaction.
People are more likely to befriend those who share their demographic background, values, attitudes and leisure activities
Even the mere belief that someone is similar to you sets the stage for a positive encounter
Marriage partners tend to become more similar over time (convergence)
The "dog-human similarity" finding: owners tend to select dogs that resemble them physically
Similar others validate our worldview, which feels rewarding
We assume similar people will like us (expected reciprocity)
We make negative inferences about people who disagree with us on important issues
Three mechanisms underlie this process:
Perceived responsiveness: similar people seem more attuned to us
Increased comfort in the interaction
Perceived shared knowledge: we assume common ground
Mimicking someone's behaviour (posture, gestures, speech patterns) makes them perceive you as more similar, which helps the interaction. This is sometimes called the "chameleon effect."
The more we see and interact with someone, the more likely they are to become our friend. This is one of the most robust findings in relationship research.
MIT housing study (Festinger, Schachter and Back): Residents of the same building were far more likely to become friends with each other than with people in nearby buildings. Both physical distance and functional distance (e.g. whose staircase you pass) mattered.
Classroom study (Moreland and Beach): Female confederates sat in the front row of a lecture without interacting with anyone. At the end of the semester, students rated these women more favourably the more often they had appeared in class, even though they had never spoken. The effect operated outside conscious awareness.
More opportunities for contact
The mere exposure effect: repeated exposure to a stimulus increases liking for it. The more you see a person (or even a photograph of them), the more you tend to like them.
Proximity predicts who becomes friends, but it also predicts who becomes enemies. If you already have a reason to dislike someone, seeing them repeatedly will intensify that dislike.
We like people who like us, and this effect can even override dissimilarity.
Gold, Ryckman and Mosley study: A woman who made eye contact, leaned in and listened attentively was liked by male participants despite perceived dissimilarity.
Crucially, this only works if the attention feels selective. If someone is equally warm to everybody, people do not feel special and the effect weakens.
Walster et al. study: Similarity in attractiveness did not predict whether someone would be asked out again. Attractive women were asked out by all men regardless of the men's own attractiveness.
Similarity matters for many dimensions of friendship, but for raw romantic attraction, physical appearance tends to dominate.
There is substantial cross-cultural agreement on what constitutes an attractive face. Commonly cited attractive features include a tanned complexion, narrow facial shape, lower body fat, fuller lips, higher cheekbones and facial symmetry.
Some variation exists: in Japan and the UK, both men and women prefer more feminised faces for long-term partners, but women in those cultures shift towards preferring more masculine features in short-term partners, especially during ovulation.
Photographs of college students morphed into composite images are consistently rated as more attractive than any individual photo. Irregularities get averaged out, producing a more symmetrical, prototypical face.
Several findings link the ovulatory cycle to attractiveness cues:
Voice attractiveness increases during ovulation (Pipitone and Gallup, 2008)
Women with higher oestradiol show stronger preferences for high-testosterone male faces (Roney and Simmons)
Ovulating women tend to dress more provocatively and have clearer skin
Ovulating exotic dancers earned roughly $70/hour at peak fertility versus $35 during menstruation (women on the pill averaged $37)
Proposed mechanisms: changes in body odour, waist-to-hip ratio, skin clarity and behaviour
Physically attractive people are judged as smarter, more successful, happier, better adjusted, more socially skilled, more confident, more assertive, and even less likely to have an STD.
There is a kernel of truth here: attractive people do tend to have better social interactions, likely because others treat them more warmly from an early age. Over time they acquire genuinely stronger social skills, a textbook example of the self-fulfilling prophecy.
Participants interacted on the phone with someone they believed to be either attractive or unattractive. Naïve observers who listened to the tapes rated people who were believed to be attractive as more friendly, likable and sociable. The reason: participants who thought they were speaking with an attractive person treated them more warmly, eliciting warmer behaviour in return.
Five major theories explain why relationships persist or dissolve.
Close relationships involve a transformation of motivation: partners shift from pure self-interest to thinking as a unit ("her dreams are my dreams"). Rusbult extended this, noting that partners often sacrifice immediate self-interest for the greater good of the relationship. A key point: stability is not the same as satisfaction.
Two forces hold relationships together:
Attraction forces are tied to satisfaction (enjoyment, love)
Barrier forces discourage leaving (children, financial ties, shared pets) and only become salient once a person begins to consider exit
Berscheid and Lopes elaborated on this: as external barriers to divorce have weakened over time, the burden of maintaining relationship quality has increased.
Satisfaction is higher when rewards from the partner and the relationship are high, costs are low, and each partner's comparison level (what they feel they deserve) is not set unrealistically high. Satisfaction, in turn, leads to commitment. Importantly, commitment also depends on investments already made and the perceived quality of alternatives.
Relationship feelings depend on three factors:
Perceived rewards
Perceived costs
The comparison level, which is the gap between what a person believes they deserve and what they have, weighed against the probability of finding something better
People are most comfortable when both partners experience a roughly equal ratio of costs to rewards. Both over-benefited and under-benefited partners feel uneasy, because equity is a powerful social norm. The norm of reciprocity reinforces this expectation.
Predictors of marital distress differ somewhat by gender:
For men: fewer years of education, cohabiting briefly before marriage, not pooling finances
For women: less education, low income, having stepchildren, high pre-marriage expectations (leading to reality-fantasy gaps), and high romance during pregnancy that drops sharply after children arrive
Differences between heterosexual and same-sex couples on these dimensions are very small.
Same-sex couples want the same things from relationships as heterosexual couples. If both partners are out, relationship satisfaction tends to be higher. Cain (1991) found that disclosing same-sex identity to others serves to build social support outside the relationship, which strengthens the relationship itself. Daily stigmatisation from people seen routinely is more stressful than holiday-only encounters with unsupportive family members.
Companionate love: deep affection without intense passion or physiological arousal, characteristic of close friendships and long-term partnerships
Passionate love: intense longing, physiological arousal, emotional highs when reciprocated and despair when things go poorly
Love consists of three components:
Intimacy: the feeling of closeness and connectedness
Passion: the "hot" component, physical and emotional arousal
Commitment: involves two decisions, a short-term one (choosing to love your partner) and a long-term one (choosing to maintain the relationship)
Different combinations of these three components produce different kinds of love (e.g. romantic love = intimacy + passion without commitment; consummate love = all three).
Cross-cultural study (Phil Shaver):
Chinese samples included "sad love" (sorrow, tenderness, pity) as part of the love concept; American samples did not
Chinese love songs reference suffering more often, though both American and Chinese love songs are equally passionate and erotic
Chinese culture emphasises interpersonal destiny or karma: if a relationship is failing, it may be seen as fated and unsalvageable
American couples tend to value passionate love more; Chinese couples value companionate love more; Kenyan couples value both equally
Marrying for love:
Most important for Americans, Brazilians, British and Australians
Less central in India, Pakistan and Thailand, where marrying for love is sometimes considered a luxury and marriages must fit within the socio-economic structure
Evolutionary psychology frames mate selection in terms of reproductive success. Women, whose reproductive investment is higher, are theorised to prioritise partners who can help raise offspring to maturity. Men, whose minimum investment is lower, are theorised to prioritise access to multiple mates.
Power and status differences (Gangestad): The more access women had to their own economic resources, the more they prioritised physical attractiveness in a partner, suggesting that preference for attractiveness is a "luxury" tied to financial independence.
Secure: comfortable with closeness, trusts others readily, experiences the most satisfying and enduring romantic relationships
Avoidant: uncomfortable with closeness, finds it hard to trust others, has less satisfying relationships and rarely falls in love
Anxious: obsessive and preoccupied with the relationship, fears that partners do not want the same level of intimacy, tends to enter relationships too quickly
The very quality that initially attracts you to someone can later become the source of the breakup. For example, a partner's "protectiveness" may initially feel caring but later manifest as possessiveness and jealousy.
Both report negative symptoms, but they differ in kind:
The breakee experiences loneliness, depression, unhappiness, anger, plus physical symptoms (headaches, nausea, disrupted eating and sleeping)
The breaker experiences guilt, unhappiness, but fewer physical symptoms
Mutual breakups are often hardest for both parties because of the shared reality and resulting regret
Men are generally less interested in remaining friends
Women are most interested in staying friends if they are the one who was broken up with
Men are most likely to want friendship if the breakup was mutual
"Opposites attract." Students often assume complementarity drives attraction. It does not. The research consistently shows that similarity is the stronger predictor of liking.
"We pair off with people at our own level of attractiveness." Walster et al. found that matching in attractiveness did not predict who would be asked out again. For initial attraction, overall attractiveness of the target dominates.
"Familiarity breeds contempt." The mere exposure effect shows the opposite: familiarity increases liking, unless there is already a reason for dislike.
"A satisfied partner will stay." The Investment Model shows that satisfaction alone does not predict commitment. Investments and lack of alternatives matter independently.
⚠️ Know all three factors of attraction (similarity, proximity, reciprocal liking) and be able to explain the mechanisms behind each
⚠️ Be able to describe the mere exposure effect and cite Moreland and Beach's classroom study as evidence
⚠️ Understand the "what is beautiful is good" effect and how the Snyder, Tanke and Berscheid telephone study demonstrates the self-fulfilling prophecy
⚠️ Be prepared to compare the five relationship theories (Interdependence, Cohesiveness, Investment, Social Exchange, Equity) and state how they differ
⚠️ Know the three components of Sternberg's Triangular Theory and be able to identify love types by their combination
⚠️ Be able to describe the three attachment styles and link each to relationship outcomes
⚠️ Cultural comparison questions are common: contrast American and Chinese views on passionate vs. companionate love and beliefs about interpersonal destiny
True or false: The mere exposure effect means that repeated contact always increases liking.
False. If you already dislike someone, repeated exposure can intensify the dislike.
Fill in the blank: According to Sternberg, consummate love requires ______, ______ and ______.
Intimacy, passion and commitment.
True or false: In the Walster et al. study, people were most likely to ask out others at their own attractiveness level.
False. Attractive women were asked out by all men regardless of the men's own attractiveness.
Fill in the blank: In Equity Theory, both ______-benefited and ______-benefited partners feel uneasy.
Over-benefited and under-benefited.
True or false: Avoidant attachment is associated with the most satisfying romantic relationships.
False. Secure attachment is associated with the most satisfying and enduring relationships.
Q: Name and explain three factors that predict interpersonal attraction.
A: Similarity (we like people who share our attitudes, values and demographics), proximity (physical closeness increases contact and triggers the mere exposure effect), and reciprocal liking (knowing someone likes us increases our liking for them).
Q: Describe the Moreland and Beach (classroom) study. What does it demonstrate?
A: Female confederates sat in the front row of a lecture for varying numbers of sessions without interacting with anyone. At the end of the semester, students rated the women they had seen most often as more attractive and likable. This demonstrates the mere exposure effect operating outside conscious awareness.
Q: What is the "what is beautiful is good" effect, and what evidence supports the idea that it involves a self-fulfilling prophecy?
A: The "what is beautiful is good" effect is the assumption that attractive people possess desirable personality traits. The Snyder, Tanke and Berscheid telephone study showed that men who believed they were talking to an attractive woman behaved more warmly, which caused the woman to respond in a friendlier way, confirming the original expectation.
Q: Compare the Investment Model and Social Exchange Theory. How do they differ?
A: Both consider rewards, costs and comparison levels. Social Exchange Theory focuses on whether the current outcome exceeds what one feels entitled to and what alternatives offer. The Investment Model adds a critical variable: the size of investments already made (time, effort, shared resources), which independently predicts commitment beyond satisfaction alone.
Q: What are the three components of Sternberg's Triangular Theory of Love? Give an example of a love type that combines only two of them.
A: Intimacy, passion and commitment. Romantic love combines intimacy and passion but lacks long-term commitment.
Q: Explain how culture influences attitudes toward love, using specific findings from the cross-cultural research discussed in the course.
A: Chinese samples include "sad love" in their concept of love and tend to value companionate love more than American couples do. American couples place greater emphasis on passionate love. Chinese beliefs in interpersonal destiny mean that struggling relationships may be seen as fated to fail, whereas Americans are more likely to believe relationships can be worked on. Marrying for love is prioritised in Western countries but is considered a luxury in some Eastern cultures (India, Pakistan, Thailand) where marriages must fit socio-economic structures.
This material connects directly to conflict and violence in relationships, which examines what happens when attraction and relationship maintenance fail (Peterson's model, demand-withdraw patterns, the ELVN model). It also connects to prosocial behaviour and altruism, because empathy and closeness predict helping behaviour, and the equity and social exchange frameworks reappear in discussions of why people help. Finally, stress research overlaps here: social rejection is one of the most potent stressors, and relationship quality is a strong predictor of both mental and physical health outcomes.
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