Difficulty: Intermediate | Prerequisites: Chapter 5 (biology-culture interaction), basic understanding of frustration and learning theory
This chapter explores why people behave aggressively and rejects the idea that aggression has a single cause. It draws on biology, frustration, learning, culture, cognition and situational factors. The chapter is heavy on theories and distinctions (hostile vs instrumental, for example), which professors test frequently. If you are comfortable with the biology-culture framework from Ch. 5, this will feel like a natural extension.
Aggression is caused by many interacting influences, not one single factor. Biology provides predispositions, frustration creates emotional readiness, learning teaches when and how to be aggressive, and situations determine whether aggression occurs. Ordinary people can become aggressive under the right circumstances.
Aggression
Behaviour intended to harm another person physically or psychologically. The key word is intent: accidental harm is not aggression.
Physical aggression
Behaviour intended to physically injure someone (hitting, kicking, assault).
Social / relational aggression
Behaviour intended to damage relationships or social standing (gossip, exclusion, humiliation, spreading rumours).
Hostile aggression
Aggression driven by anger. It is emotional, impulsive and reactive. Example: punching someone during an argument.
Instrumental aggression
Aggression used as a means to achieve a goal. It is calculated, strategic and planned. Example: robbery involving violence.
In simple terms, hostile aggression is hot (anger-driven); instrumental aggression is cold (goal-driven).
Frustration-aggression theory
Frustration (blocked goals) creates readiness for aggression. The original version claimed frustration always leads to aggression; the revised version says it does not always lead to violence.
Berkowitz revision
Frustration produces anger and readiness for aggression, but environmental cues (such as the presence of weapons) determine whether aggression occurs.
Relative deprivation
Feeling deprived compared to others. Aggression is often driven not by absolute poverty but by perceived unfairness and comparison.
Social learning theory (Bandura)
Aggression is learned through observation, imitation and reinforcement. The Bobo Doll study demonstrated that children copy aggressive behaviour they observe in adults.
Instinct theory
Aggression is innate and biologically programmed. Freud proposed a death instinct (Thanatos); Lorenz argued aggression evolved for survival. The chapter criticises this as oversimplified.
Testosterone
Hormone associated with dominance and aggression. The relationship is complicated: testosterone links more strongly to dominance than to direct violence.
Alcohol myopia
Alcohol narrows attention to immediate cues, reduces judgement and increases impulsivity, which increases aggression.
Weapons effect
The presence of weapons increases aggressive thoughts and behaviour. Weapons act as aggression-related cues that psychologically prime aggression.
Excitation transfer
Arousal from one source (e.g. exercise) can intensify reactions to another situation (e.g. an argument feels more intense).
Desensitisation
Reduced emotional response to violence after repeated exposure. Violence begins to feel normal and less shocking.
Social scripts
Learned expectations for behaviour in situations. Media can teach scripts about how conflicts should be solved.
Catharsis hypothesis
The idea that releasing aggression reduces future aggression. Research generally disproves this: acting aggressively often strengthens and rehearses aggressive behaviour.
Deindividuation
Loss of self-awareness and restraint in groups, caused by anonymity, crowds, uniforms or darkness.
Diffusion of responsibility
Reduced personal accountability in groups. People may behave more aggressively in crowds because responsibility feels shared.
Social contagion
The spread of aggressive behaviour through groups (e.g. riots escalate because aggression spreads socially).
Physical aggression aims to injure the body. Social or relational aggression aims to damage relationships and social standing. Men show more physical aggression; women often show more relational aggression, though overall differences are smaller than stereotypes suggest.
Hostile aggression is driven by anger (emotional, impulsive, reactive). Instrumental aggression is goal-driven (calculated, strategic, planned). This distinction is heavily tested.
Instinct theory: Freud proposed a death instinct (Thanatos) that builds internally and seeks release. Lorenz argued aggression evolved because it aided survival, protected territory and secured mates. The chapter criticises instinct theory as oversimplified and unable to explain cultural variation.
Frustration-aggression theory: Blocked goals produce frustration, which produces aggression. The original version was too absolute. The Berkowitz revision adds that frustration produces anger and readiness for aggression, but environmental cues (especially the presence of weapons) determine whether aggression occurs.
Relative deprivation: Aggression is often driven not by absolute poverty but by perceived unfairness. "If others have more than me unfairly" is the trigger.
Social learning theory (Bandura, very important): Aggression is learned through observation, imitation and reinforcement. The Bobo Doll study showed children copy aggressive behaviour from adults. People imitate behaviour when it is rewarded, when models are admired and when aggression appears effective. Sources include parents, peers, media and culture.
The amygdala is associated with fear, anger and emotional reactions; overactivity may increase aggression. The frontal lobe handles impulse control, planning and self-regulation; damage may reduce restraint. Genes contribute predispositions to aggression, not destiny. Testosterone is linked more to dominance than to direct violence. Alcohol increases aggression through alcohol myopia (narrowed attention, reduced judgement, increased impulsivity).
Unpleasant experiences increase aggression: heat, pain, insults and crowding. Violence tends to rise during hotter weather. Arousal from one source can intensify reactions to another (excitation transfer). The weapons effect shows that the mere presence of weapons primes aggressive thoughts.
Violent media increases aggression through several mechanisms: imitation (copying observed behaviour), desensitisation (violence feels normal after repeated exposure), social scripts (media teaches how conflicts should be resolved) and cognitive priming (violence activates aggressive thoughts).
The catharsis hypothesis, the idea that releasing aggression reduces future aggression, is generally disproved. Acting aggressively strengthens and rehearses aggressive behaviour.
Violent video games increase aggressive thoughts, feelings and behaviour while decreasing empathy and sensitivity to violence. The chapter does not claim video games alone create violent criminals; they are one contributing factor.
Diffusion of responsibility means reduced personal accountability in groups. Deindividuation (loss of self-awareness in crowds, anonymity, uniforms, darkness) leads to impulsive behaviour and reduced self-control. Social contagion spreads aggressive behaviour through groups, which is why riots can escalate.
Students often confuse hostile and instrumental aggression. A bar fight driven by anger is hostile. A robbery using violence to get money is instrumental. The motive is the distinguishing factor.
Students sometimes believe the catharsis hypothesis is supported by research. It is not. "Letting it out" tends to increase, not decrease, aggression.
Students often think testosterone directly causes violence. The relationship is more about dominance and status-seeking than direct physical aggression.
Students sometimes assume aggression is purely biological or purely learned. The chapter's central message is that it emerges from the interaction of many factors.
⚠️ The hostile vs instrumental aggression distinction is a favourite exam question. Know examples of each.
⚠️ Social learning theory and the Bobo Doll study are core material.
⚠️ The catharsis hypothesis being false is a common true/false or multiple-choice question.
⚠️ The weapons effect, alcohol myopia and excitation transfer are specific mechanisms professors test.
⚠️ Deindividuation and diffusion of responsibility connect to group behaviour chapters.
⚠️ Know that frustration-aggression theory was revised (Berkowitz) and what the revision added.
True or false: Accidental harm counts as aggression. (False. Aggression requires intent.)
Fill in the blank: Aggression driven by anger is called ________ aggression; aggression used to achieve a goal is called ________ aggression. (hostile; instrumental)
True or false: The catharsis hypothesis is well supported by research. (False. Acting aggressively tends to increase future aggression.)
Fill in the blank: Berkowitz revised frustration-aggression theory by adding the role of ________. (environmental cues, such as weapons)
True or false: Deindividuation increases self-awareness. (False. It decreases self-awareness.)
Q: Distinguish between hostile and instrumental aggression. Provide an example of each.
A: Hostile aggression is driven by anger and is impulsive and reactive (e.g. punching someone during an argument). Instrumental aggression is a calculated means to a goal (e.g. a mugger using force to steal a wallet). The key difference is whether the motivation is emotional or strategic.
Q: Explain Bandura's social learning theory of aggression and describe the Bobo Doll study.
A: Social learning theory proposes that aggression is learned through observation, imitation and reinforcement. In the Bobo Doll study, children watched an adult behave aggressively toward an inflatable doll. Later, the children imitated the aggressive behaviour. This demonstrated that aggression can be learned by watching others, especially when the behaviour is rewarded or the model is admired.
Q: Why does the chapter argue that the catharsis hypothesis is false?
A: Research shows that acting aggressively does not reduce future aggression. Instead, it strengthens and rehearses aggressive behaviour, making it more likely to recur. Venting anger (e.g. punching a pillow) tends to maintain or increase aggressive impulses rather than releasing them.
Q: Describe three mechanisms through which violent media can increase aggression.
A: First, imitation: people copy aggressive behaviour they observe in media. Second, desensitisation: repeated exposure to violence reduces emotional response, making violence feel normal. Third, social scripts: media teaches expectations about how conflicts should be resolved, and repeated violent scripts normalise aggressive solutions.
Aggression connects to Ch. 5's biology-culture interaction, Ch. 9's scapegoating and displaced aggression, and later material on group behaviour and conformity. Social learning theory appears across multiple chapters.
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