Social Behaviour
High-Yield Summary
- Attraction drivers: similarity, self-disclosure (must be reciprocated), reciprocal liking, proximity (via mere exposure/familiarity effect). Facial symmetry and golden-ratio body proportions boost attractiveness. 'Opposites attract' still needs some underlying shared similarity.
- Aggression: amygdala ↑ aggression (flags threats), prefrontal cortex ↓ aggression (regulates amygdala — lower PFC activity = more aggression), testosterone ↑ aggression. Berkowitz's cognitive neoassociation model: negative emotional states (tired, sick, frustrated, in pain) raise aggressive response likelihood.
- Ainsworth's Strange Situation — 4 attachment styles: secure (preference + consistent comfort-seeking), avoidant (no preference, no distress either way), ambivalent/anxious (distress at separation, inconsistent response at return), disorganized (no clear pattern, red flag for abuse).
- 5 types of social support: emotional (listening/empathy), esteem (affirming qualities), material/tangible (money/goods), informational (facts/explanation), network (sense of belonging). High support → better mental/physical health outcomes.
- Foraging driven by hypothalamus: lateral hypothalamus = hunger, ventromedial hypothalamus = satiety. Mating systems: monogamy, polygyny (1 male–many females), polyandry (1 female–many males), promiscuity (no exclusivity).
- Mate choice mechanisms: phenotypic benefits, sensory bias, Fisherian/runaway selection (trait exaggerates via feedback regardless of survival value — peacock tail), indicator traits (honest signal of health — shiny coat), genetic compatibility (reduces recessive disease risk).
- Game theory 2x2 by who gains/loses: cooperation (both gain), spite (both lose), altruism (donor loses, recipient gains), selfishness (donor gains, recipient loses). ESS (Maynard Smith) — Hawk-Dove game shows 2 strategies can coexist stably. Inclusive fitness (Hamilton): success measured via own + relatives' reproductive success — explains self-sacrificing altruism.
Key Terms
- Mere exposure effect
- People prefer stimuli (including people) they've been exposed to more frequently; also called the familiarity effect.
- Cognitive neoassociation model
- Berkowitz: negative emotional states (pain, fatigue, frustration) raise the likelihood of an aggressive response.
- Secure attachment
- Clear caregiver preference, consistent comfort-seeking pattern; upset at departure, comforted by return.
- Disorganized attachment
- No clear behavioral pattern to caregiver absence/presence; associated with caregiver abuse.
- Fisherian/runaway selection
- Positive-feedback mechanism where a trait becomes progressively exaggerated simply because it's desirable, independent of survival value.
- Indicator trait
- A trait that signals genuine good health/fitness, increasing attractiveness (e.g., a shiny coat).
- Empathy-altruism hypothesis
- Batson: people help others when they feel empathy for them, regardless of personal cost (debated).
- Inclusive fitness
- Hamilton: measure of reproductive success that includes the success of genetically related individuals, not just direct offspring.
Four Attachment Styles (Ainsworth)
| Style | Preference / Response pattern |
|---|---|
| Secure | Clear preference; consistent, comfort-seeking |
| Avoidant | No preference; little/no distress either way |
| Ambivalent (anxious) | Distress at separation; inconsistent/mixed response at return |
| Disorganized | No clear pattern; red flag for abuse |
Game Theory Outcomes (Gain/Loss Grid)
| Outcome | Donor / Recipient |
|---|---|
| Cooperation | Both gain |
| Spite | Both lose |
| Altruism | Donor loses, recipient gains |
| Selfishness | Donor gains, recipient loses |
Common MCAT Trap
- Lower prefrontal cortex activity means MORE aggression (less regulation of the amygdala), not less — easy to flip the direction.
- Sort attachment by two questions: is there caregiver preference, and is the response pattern consistent? Don't just pattern-match to a single keyword.
- Fisherian selection (feedback-driven, survival value irrelevant) vs. indicator traits (attractive because they ARE an honest fitness signal) — both explain attractive traits but via opposite logic.
- Use gain/loss for game theory instead of memorizing 4 terms in isolation: both gain = cooperation, both lose = spite, donor loses = altruism, donor gains = selfishness.
Quick Recall
An infant shows no distress when the caregiver leaves and no relief when they return, and treats a stranger the same as the caregiver. Which attachment style?
A peacock's tail is costly and offers no survival advantage, yet keeps becoming more exaggerated over generations. Which mate choice mechanism?
An organism sacrifices itself to protect the young of its group, ensuring gene transmission despite its own death. Which concept explains this?
A friend both gains and you both gain from splitting a task evenly. Which game theory outcome?
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