Difficulty: Intermediate | Prerequisites: Week 9 (Emotions), basic evolutionary psychology concepts.
Relationships are protracted or recurring shared social experiences shaped by how participants relate to one another. This first part covers the need to belong, attachment theory (infant and adult), Sternberg's Triangular Model of Love, and the science of physical attractiveness. If you have not covered emotions (Week 9) and evolutionary mismatch, review those first. The emotional systems described there underpin attachment, passionate love, and mate selection. Week 12 continues with relationship maintenance, failure, friendship, and commitment.
Humans have a fundamental need to belong, rooted in cooperative survival. Attachment theory describes how infant bonding (secure, avoidant, ambivalent, disorganised) sets the template for adult relationships through an internal working model. Sternberg's Triangular Model breaks love into three components (passion, intimacy, commitment) whose combinations define different relationship types. Physical attractiveness matters more than folk psychology admits, with universal features (symmetry, skin clarity, warmth) and sex-differentiated preferences.
Attachment Theory
Describes the fundamental relational bonding mechanisms found in all social mammals. Covers the affective and motivational states related to seeking and maintaining proximity with something important (typically a primary caregiver). In simple terms, it explains why babies cling to their parents and why adults form deep bonds.
The Strange Situation Task
A laboratory procedure devised by Mary Ainsworth to measure infant attachment behaviour. The critical stage is when the infant reunites with the caregiver after distress, revealing whether the child calms down (and how).
Secure Attachment
Infant attachment style characterised by low anxiety and low avoidance. Associated with highly attentive, warm, and reliable care.
Avoidant Attachment
Infant attachment style characterised by low anxiety and high avoidance. Associated with care that is infrequent or comes late.
Ambivalent Attachment
Infant attachment style characterised by high anxiety and low avoidance. Associated with inconsistent care that is sometimes aloof, sometimes attentive, unpredictably.
Disorganised Attachment
Infant attachment style with no consistent pattern, possibly high on both anxiety and avoidance. Most often a blend of other styles. The only consistency is a maladaptive, docile response to abuse.
Internal Working Model
The mental template for later relationships calibrated by infant attachment. Sets default expectations about one's own worth (anxiety dimension) and others' trustworthiness (avoidance dimension).
Sternberg's Triangular Model of Love
A model proposing that all major relationships can be described by combinations of three components: passion, intimacy, and commitment.
Passionate Love
Intense, physiologically arousing love centred on attraction and desire. Short-lived and novelty-driven.
Companionate Love
Love characterised by intimacy and commitment but reduced passion. The form that sustains long-term relationships.
Consummate Love
The combination of all three components (intimacy, passion, commitment), often called the "honeymoon period."
Propinquity
A combination of geographic proximity and functional distance (how often you make contact). One of the strongest statistical predictors of friendship formation.
A relationship is a protracted or recurring shared social experience between two or more people, where each participant's experience is shaped in relation to the other.
We are cognitively primed to categorise relationships into types: romantic, familial (parents, children, siblings, fictive kin), friendships/collaborations, and community/organisation membership.
A fundamental motivational drive in humans and most social animals.
Most animals gain cooperative advantages from social interaction that are crucial to survival.
Baumeister and Leary: "The need is for frequent, non-aversive interactions within an ongoing relational bond."
Attachment is the most essential component of relationship formation and maintenance.
Attachment Theory describes fundamental relational bonding mechanisms found in all social mammals, covering the affective and motivational states related to seeking and maintaining proximity with something important.
Infant Attachment:
Harry Harlow demonstrated that attachment behaviours constitute a primary, evolutionarily primed drive in primates (not just about food, but about comfort and intimacy).
John Bowlby developed human attachment theory; his student Mary Ainsworth devised the Strange Situation Task.
The critical stage of the Strange Situation is the infant reuniting with the caregiver after distress: does it calm down?
Four Attachment Styles (in order of prevalence):
Secure: low anxiety, low avoidance. Attentive, warm, reliable care.
Avoidant: low anxiety, high avoidance. Care is infrequent or comes late.
Ambivalent: high anxiety, low avoidance. Inconsistent, unpredictable care.
Disorganised: no consistent pattern, possibly high on both. Often a blend; the only consistency is a maladaptive docile response to abuse.
The latter three are collectively called "insecure" attachment styles.
Adult Attachment: strong correlations between infant attachment style and adult intimacy patterns. The anxiety and avoidance dimensions of infant attachment calibrate our Internal Working Model, setting default expectations of our own worth and others' trustworthiness.
All relational attachment and bonding is grounded in the social emotional states of compassion, caring, liking, and attraction. Sternberg's model clusters these into three components whose combinations define relationship types:
Liking (intimacy alone) = Friendships
Infatuation (passion alone) = Crushes/Flings
Empty love (commitment alone) = Principled commitment
Romantic love (intimacy + passion) = Early modern marriage
Fatuous love (passion + commitment) = Early traditional/arranged marriage
Companionate love (intimacy + commitment) = Late modern marriage
Consummate love (all three) = The "honeymoon period"
Physical attractiveness has evolutionary significance and matters more than most people admit when selecting romantic partners.
Desirable traits collapse together in people's judgements, suggesting deficits in one factor can be compensated by another:
Warmth pairs with Trustworthiness
Vitality pairs with Attractiveness
Status pairs with Resources
Universal features of attractiveness: facial symmetry, skin clarity, signs of kindness, warmth, and humour.
Features considered mostly attractive on women: large eyes, full lips, small nose, prominent cheekbones, happiness.
Features considered mostly attractive on men: blocky/ridged features, prominent chin and brow, emoting pride.
Do opposites attract? No. Similarity in key domains does, and so does complementarity.
Does absence make the heart grow fonder? Only in the short term; generally it strains relationships.
Does reciprocation of feelings matter? Yes. People like those who they believe like them, and unreciprocated feelings can produce hostility.
Attachment theory informs clinical approaches to relationship therapy: understanding a partner's attachment style (and your own) helps explain recurring conflict patterns. The finding that looks matter more than people admit is used in marketing, hiring research, and dating app design.
Students often assume "insecure attachment" means something went wrong. The three insecure styles (avoidant, ambivalent, disorganised) are adaptive responses to specific caregiving environments. Only disorganised attachment is consistently maladaptive.
Sternberg's model does not rank types of love as better or worse. Companionate love is not a "lesser" form; it is the sustainable form that keeps long-term relationships alive.
The idea that "opposites attract" is a persistent folk belief. The evidence shows the opposite: similarity in key domains (interests, values, worldview) is a stronger predictor.
Students sometimes conflate passion with love. In Sternberg's model, passion is only one of three components. A relationship with passion alone is infatuation, not love.
⚠️ Know the four attachment styles, what caregiving conditions each is adaptive for, and which are "insecure."
⚠️ Be able to explain what the Internal Working Model is and how infant attachment calibrates adult relationship expectations.
⚠️ Know all seven combinations of Sternberg's three components and which relationship type each produces.
⚠️ The Strange Situation Task is frequently tested. The critical stage is the reunion after distress.
⚠️ Harlow's contribution: infant primates regulate anxiety via intimacy and are born seeking it (not just food).
⚠️ "Do opposites attract?" is a common exam question. Answer: no, similarity and complementarity predict attraction.
True or False: Avoidant attachment is characterised by high anxiety and high avoidance. (False. It is low anxiety, high avoidance.)
Fill in the blank: The three components of Sternberg's Triangular Model are passion, intimacy, and ______. (Commitment.)
True or False: Companionate love consists of passion and commitment. (False. It is intimacy and commitment.)
Fill in the blank: The key stage of the Strange Situation Task is the ______ after distress. (Reunion with the caregiver.)
True or False: Opposites attract in romantic relationships. (False. Similarity in key domains predicts attraction.)
Q: What is a relationship, technically speaking?
A: A protracted or recurring shared social experience with two or more people.
Q: What is Attachment?
A: A set of relational bonding mechanisms that supply an animal with a desire to seek and maintain proximity with another (primary caregiver).
Q: What did Harlow discover about the nature of attachment/comfort?
A: Infant primates regulate anxiety via intimacy and are born seeking it.
Q: What are the four general attachment styles seen in infants?
A: Secure, Avoidant, Ambivalent, and Disorganised (in order of prevalence).
Q: What parenting circumstance is Secure Attachment adaptive for?
A: Parents who are attentive, warm, and have adequate resources.
Q: What parenting circumstance is Avoidant Attachment adaptive for?
A: Situations (usually lack of resources, sometimes parental depression) where the parent is unavailable or slow to respond.
Q: In Sternberg's Triangular Model, what are the three primary relational phenomena?
A: Passion (for infatuation), Intimacy (for liking), and Commitment.
Q: Which two relational aspects comprise Romantic Love?
A: Passion and Intimacy.
Q: Do looks matter for most people when selecting romantic partners?
A: Yes, more than most things.
Q: Do opposites attract?
A: No. Similarity in key domains does, and so does complementarity.
This connects to Emotions (Week 9) because passionate love involves the same physiological arousal systems. It connects to Relationships Part 2 (Week 12) which covers how relationships are maintained, why they fail, and the role of friendship and commitment. It connects to Prejudice (Week 13) because attachment styles and ingroup bonding mechanisms feed into how we relate to outgroups.
Relationships, attachment theory, John Bowlby, Mary Ainsworth, Strange Situation, secure attachment, avoidant attachment, ambivalent attachment, disorganised attachment, insecure attachment, internal working model, Harry Harlow, need to belong, Baumeister and Leary, Sternberg triangular model, passionate love, companionate love, consummate love, infatuation, romantic love, fatuous love, empty love, liking, physical attractiveness, facial symmetry, mate selection, similarity, propinquity, mere exposure, reciprocation, PSY 301, social psychology, NYU