Difficulty: Intermediate | Prerequisites: Evolutionary psychology basics, moral intuitions (Week 5), Social Identity Theory.
This topic covers prosocial behaviour (helping, cooperating, altruism) through the lens of Game Theory and Behavioural Economics. It traces the evolutionary origins of cooperation (kin selection, Hamilton's Rule), introduces Social Value Orientation as a framework for individual differences, and examines the dynamics of free-riding, the Tragedy of the Commons, and altruistic punishment. If you have not covered moral intuitions from Week 5, review those first.
Helping, cooperating, and altruism are distinguished by intention: cooperation aims for mutual benefit, altruism benefits only others (often at a cost). Game Theory studies decision-making under constraints (limited resources, incomplete information, uncertain intentions of others). Prosocial behaviour in non-human animals traces to kin selection (Hamilton's Rule: rB - C > 0). Most people are Prosocial in their Social Value Orientation, followed by Individualistic, Competitive, and (very rarely) Altruistic. Free-riders exploit cooperative systems, leading to the Tragedy of the Commons, and are policed through altruistic punishment, which is most effective when coordinated through social norms.
Helping
Broadly construed, any action that benefits others.
Cooperating
Acting together for mutual benefit.
Altruism
Actions that only benefit others, often at a personal cost. Distinguished from cooperation by intention.
Game Theory
The study of decision-making under constraints: limited time/resources, incomplete or uncertain knowledge, and an inability to reliably gauge the intentions of others.
Behavioural Economics
The discipline formed by combining Game Theory, Economics, and Social/Cognitive Psychology.
Kin Selection
The evolutionary mechanism explaining prosocial behaviour in non-human animals: organisms help relatives because shared genes are passed on.
Hamilton's Rule
rB - C > 0. The cost to self must be outweighed by the benefit to the other multiplied by their genetic relatedness. This is the formal expression of kin selection. In simple terms, you are more likely to sacrifice for close relatives because they share more of your genes.
Social Value Orientation
A theory describing individual differences in dispositional tendencies toward cooperation. Four categories: Individualistic, Competitive, Altruistic, Prosocial.
Inequality Aversion
Our intuitive dislike of obviously unfair situations, as much an aesthetic judgement as a moral one.
Joint Maximisation
The temptation to form cartel-like deals that allow you and your rivals to collectively benefit from an external resource base (e.g. price-gouging tourists).
Free-Rider
Someone who reaps the benefits of cooperation but avoids the costs.
Tragedy of the Commons
Otherwise honest individuals may exploit shared resources (despite collective ruin) out of fear of being outcompeted by free-riders.
Altruistic Punishment
Incurring a personal cost to punish a free-rider for the sake of the whole group. Most effective when coordinated so that many people punish together, which is generally managed through social norms.
Helping (broadly): actions benefiting others. Cooperating: acting together for mutual benefit. Altruism: actions that only benefit others, often at a cost.
Intention is what distinguishes altruism from cooperation.
Game Theory studies decision-making under constraints: limited time/resources, incomplete knowledge, and inability to gauge others' intentions.
Behavioural Economics combines Game Theory with economics and social/cognitive psychology.
Evolutionary Psychology and Comparative Ethology provide a rich understanding of the phylogenetic history of prosocial ("moral") tendencies.
Natural selection being described as inherently "selfish" leads to public confusion. Kin selection explains how apparently selfless behaviour is gene-level rational.
Hamilton's Rule: rB - C > 0 (relatedness times benefit to other, minus cost to self, must exceed zero).
We biologically inherit roughly five basic moral intuitions (Week 5). The one most obvious in monkeys is fairness (the grape reward vs. cucumber reward experiment).
Four categories:
Individualistic: maximise own resources, indifferent to others
Competitive: increase own resources, minimise those of others
Altruistic: indifferent to own resources, maximise for others
Prosocial: try to increase own and others' resources equally
Distribution: Prosocial is the easy majority, Individualistic is most of the rest, Competitive is an appreciable but small number, Altruistic is very rare.
Competitiveness is the orientation linked to testosterone levels (in both sexes, but especially cisgender men).
Inequality Aversion: our intuitive dislike of obviously unfair situations.
Joint Maximisation: the temptation to form cartel-like deals.
In real-world one-off trials of the Prisoner's Dilemma, roughly 20% of people choose to cooperate despite the risks, far higher than the Rational Actor model predicts.
What motivates individual altruism: positive feelings, improved mood, improved reputation/status, religious reward.
Greater empathy improves altruistic behaviour, but our intuitive empathy is limited by distance, time, and similarity.
Free-riders reap the benefits of cooperation but avoid the costs.
Tragedy of the Commons: otherwise honest individuals may exploit shared resources out of fear of being outcompeted by free-riders.
Altruistic Punishment: incurring a cost to punish a free-rider for the group's sake. Free-rider retaliation ruins it (free-riders can afford more). Most effective when coordinated so many punish together, generally managed moralistically through social norms.
Students often think "selfish gene" means organisms are selfish. Kin selection shows that gene-level selfishness produces organism-level altruism toward relatives.
Altruism in this course has a technical definition (benefits only others, often costly). Everyday uses of "altruism" are looser. On an exam, use the technical definition.
The Tragedy of the Commons is not about greed. It is about rational fear: even honest people exploit shared resources when they fear being outcompeted by free-riders.
⚠️ Know the distinction between helping, cooperating, and altruism. Intention is the key differentiator.
⚠️ Hamilton's Rule (rB - C > 0) and what each variable stands for.
⚠️ The four Social Value Orientations and their relative prevalence.
⚠️ The Prisoner's Dilemma: what the rational actor model predicts (defect) vs. what people actually do (~20% cooperate).
⚠️ The Tragedy of the Commons and why altruistic punishment fails when free-riders retaliate.
⚠️ Competitiveness linked to testosterone levels.
Fill in the blank: The key difference between cooperation and altruism is ______. (Intention. Cooperation aims for mutual benefit; altruism benefits only others.)
True or False: Hamilton's Rule states rB - C < 0. (False. It states rB - C > 0.)
Fill in the blank: The four Social Value Orientations are Individualistic, Competitive, Altruistic, and ______. (Prosocial.)
True or False: In one-off Prisoner's Dilemma trials, nobody cooperates. (False. About 20% cooperate.)
Fill in the blank: Altruistic Punishment is most effective when it is ______. (Coordinated, so many punish together.)
Q: What is Game Theory (technical definition)?
A: The study of decision-making under constraints (time/resource/info).
Q: What is the source of prosocial behaviour in non-human animals?
A: Kin Selection, as embodied in Hamilton's Rule.
Q: What is Hamilton's Rule?
A: rB - C > 0. Relatedness times benefit to other, minus cost to self, must exceed zero.
Q: Name the four Social Value Orientations.
A: Individualistic, Competitive, Altruistic, Prosocial.
Q: What is a Free-Rider?
A: Someone who reaps the benefits of cooperation but avoids the costs.
Q: What is the Tragedy of the Commons?
A: Otherwise honest individuals may exploit shared resources (despite collective ruin) out of fear of being outcompeted by free-riders.
Q: What is Altruistic Punishment?
A: Incurring a cost to punish a free-rider for the sake of the whole group.
Q: Which Social Value Orientation is linked with testosterone levels?
A: Competitiveness (in both sexes, but especially cisgender men).
This connects to Relationships (Week 12) because Social Exchange Theory describes how friendships transition from transactional helping to genuine care. It connects to Prejudice (Week 13) because ingroup/outgroup dynamics determine who receives prosocial behaviour. It connects to Group Dynamics (Week 15) because social loafing is a variant of the free-rider problem and the Tragedy of the Commons.
Helping, cooperating, altruism, Game Theory, Behavioural Economics, Prisoner's Dilemma, kin selection, Hamilton's Rule, moral intuitions, fairness, Social Value Orientation, individualistic, competitive, altruistic, prosocial, inequality aversion, joint maximisation, free-rider, Tragedy of the Commons, altruistic punishment, testosterone, empathy, evolutionary psychology, comparative ethology, PSY 301, social psychology, NYU