STUDIES: aggression

what is aggression — definitions.

Term	Definition
Aggression	Any behaviour directed toward another person with the immediate intent to cause harm, where the target is motivated to avoid that harm. (Widely used social-psych definition.)
Forms of aggression	Physical (hitting), verbal (insults), indirect/relational (rumours), instrumental (goal-driven), hostile (anger-driven).
Key insight	Aggression is behaviour, not anger or thoughts.

determinants of aggression.

Type	Examples
Person-centred	Personality traits, gender, alcohol, disinhibition (deindividuation, dehumanisation).
Situation-centred	Heat, noise, crowding, frustration, weapons effect, social disadvantage, cultural norms.

biological theories of aggression.

Concept	Summary
innate drive model (Freud, 1905; Lorenz, 1966).	Aggression is inborn and instinctual.
Limitation	Fails to explain cross-cultural variation or aggression toward kin.
Strength	Falsification of this model = crucial for advancement of aggression theories in psychology.
Evidence issues	Weak empirical support; ignores social/contextual influences.

psychodynamic theories of aggression.

Term	Explanation
Eros (Life instinct)	Drives self-preservation, pleasure.
Thanatos (Death instinct)	Generates aggressive impulses; energy redirected outward leads to aggressive behaviour.
Underlying idea	Aggression is inevitable and must be regulated.

evolutionary psychology & aggression.

Concept	Description
Adaptiveness	Aggression evolved because it conferred advantages to genes/kin (e.g., competition for mates, protection of offspring).
Animals	Fight for dominance, survival, reproduction.
Humans	Aggression used to secure resources, status, protection.
Limitation	Cannot easily explain harmful aggression toward close family or counter-productive violence.

social theories of aggression.

Concept	Explanation
Core idea	Frustration (blocked goal) → drives aggression.
Displacement (scapegoating)	If source is unavailable, too powerful, or unclear → aggression redirected toward a safer target.
Limitations	Mixed evidence; not all frustration causes aggression; overly simplistic.

cathartic hypothesis

Term	Definition
Catharsis	Acting out aggression reduces pent-up anger and restores emotional balance.
Forms	Direct aggression, displaced aggression, or vicarious aggression (e.g., watching violent media).
Empirical verdict	Largely disconfirmed; aggression tends to increase rather than decrease.

excitation-transfer model (Zillmann, 1979/1988).

Concept	Explanation
Residual arousal	Arousal from previous event lingers and intensifies later emotions.
Transfer	If a situational cue triggers anger, leftover arousal increases aggression.
Key point	Arousal is non-specific — from exercise, fear, humour, etc.

operant conditioning (Skinner, 1953).

Concept	Explanation
Aggression learned via consequences	Behaviour repeated if reinforced (rewarded).
Example	Child hits to regain toy → success reinforces aggression.
Key insight	Aggression persists when rewarded, and stops when punished.

social learning theory (Bandura, 1977).

Concept	Explanation
Observational learning	People learn aggression by watching models (parents, peers, media).
Vicarious reinforcement	Seeing others rewarded for aggression increases imitation.
Bobo Doll experiment (Bandura, 1961, 1963).	live aggressive model + video model + control. gender diff in aggression: girls = verbally aggressive, boys = physically aggressve. model gender influence: boys = male model imitated, girls = female model imitated.

summary of major models of aggression.

Category	Theories
Biological	Evolutionary psychology.
Social / Cognitive	Frustration-Aggression Hypothesis, Cathartic Hypothesis, Cognitive Neoassociationalist Model, Excitation-Transfer Model.
Learning	Operant Conditioning, Social Learning Theory.

key term summary.

Term	Definition
Displacement	Redirecting aggression to a safer target.
Catharsis	Idea that venting reduces aggression (disconfirmed).
Weapons effect	Aggression increases in presence of a weapon.

Term	Definition
Residual arousal	Arousal leftover from previous activity; amplifies later aggression.
Vicarious reinforcement	Learning from rewards given to others.
Deindividuation	Loss of self-awareness leading to disinhibited aggression.

Term	Definition
Frustration	Blocking of a goal-directed behaviour.
Aggressive cues	Objects/signals that prime aggression (e.g., weapons).
Innate drive	Biological impulse toward aggression.

dollard et al. (1939) — frustration-aggression hypothesis.

• core idea: frustration from blocked goals triggers aggression.

• example: traffic jams, unfair treatment → increased hostility or aggression.

• refinements: berkowitz (1989) argued frustration creates anger readiness, which interacts with cues to produce aggression.

• exam link: “evaluate the frustration-aggression hypothesis in explaining situational aggression.”

bandura (1961/1965) — social learning theory of aggression / “bobo doll” experiment.

• aim: to test whether aggression can be learned by observation and imitation of models.

• procedure: children observed adult model acting aggressively toward a Bobo doll; afterwards, placed in a room with the doll and observed for imitative aggressive behaviours.

• results: children who saw aggressive model performed significantly more aggressive acts (e.g., ~100% more acts) than controls.

• conclusion: aggression can be acquired via modelling and vicarious reinforcement, not only by direct frustration.

• exam link: “evaluate social learning theory in explaining aggression (with reference to Bandura).”

berkowitz (1969/1989) — weapons effect/cognitive neoassociationalist STUDY.

• aim: to investigate how environmental cues (e.g., presence of weapons) influence aggressive responses, particularly following arousal.

• hypothesis: an aroused individual exposed to aggressive cues will show increased aggression.

• procedure: participants provoked (e.g., electric shock) then in presence vs absence of weapons asked to deliver shock to someone else.

• results: e.g., presence of a gun increased average shock intensity by ~50% compared to control.

• conclusion: aggression is influenced by arousal + environmental cues that activate aggressive associative networks (neoassociation).

• exam link: “describe the weapons effect and how cognitive factors mediate aggression.”

cognitive neoassociationalist model - berkowitz (1989).

Concept	Explanation
trigger-based model	hypothesized, albeit controversially, that aggressive cues (eg: violent media content) can be a moderator for the relationship between frustration and aggression.
environmental cues	weapons, hostile words, aggressive people, media.
mechanism	cues prime aggressive thoughts → increased likelihood of aggressive behaviour.

• berkowitz (1989): developed his CNA model as a modification to the frustration-aggression hypothesis (dollard et al., 1939)— main premise of CNA model = negative affect is the main cause of anger and affective aggression. 

anderson & bushman (2002) — general aggression model (GAM).

• aim: to provide an integrative framework for aggression combining person and situation factors, cognition, affect, arousal and decision-processes.

• procedure: meta-analysis and theoretical review of aggression research.

• results: they show that situational (e.g., violent media) and personal (e.g., trait aggressiveness) factors increase risk of aggression via internal state (cognition + affect + arousal) leading to aggressive behaviour.

• numerical insight: effect sizes for violent media → aggressive thoughts ~ r = .17; aggressive behaviour ~ r = .13 (in many studies) though moderation by other factors.

• conclusion: aggression is multiply determined and dynamic; interventions must target multiple levels.

• exam link: “explain the general aggression model (GAM) and its implications for prevention of violence.”

tremblay et al. (1998) — early physical aggression longitudinal study.

• aim: to track young children’s physical aggression trajectories and link early aggression to later violent behaviour.

• procedure: followed ~ 1,037 Canadian boys from ages ~6 to ~15; measured aggressive behaviour in early childhood and later outcomes (juvenile delinquency).

• results: boys in the high-aggression trajectory group (~10% of sample) accounted for ~50% of later violent convictions.

• conclusion: early onset, stable aggression trajectories predict future serious violence — suggesting individual-difference (trait) components.

• exam link: “discuss developmental predictors of aggression.”

dabbs et al. (1996) — testosterone and aggression in fraternity men.

• aim: examine correlation between testosterone levels and aggressive behaviour in real-world social groups.

• procedure: measured testosterone in 240 men from 12 US fraternities; assessed descriptions of fraternity behaviour (violent/competitive).

• results: higher testosterone significantly correlated with fraternity chapters rated as more physically aggressive (r ≈ .46).

• conclusion: biological factors (hormones) contribute to aggression risk but not alone.

• exam link: “explain biological correlates of aggression (using Dabbs et al.).”

zimbardo, et al. (1973) — stanford prison experiment (SPE).

• aim: to examine how strong situational forces (prison environment) influence aggression and abusive behaviour.

• procedure: male college students randomly assigned as “guards” or “prisoners” in simulated prison; study planned for 14 days but ended after 6 days due to ethical issues.

• results: guards rapidly adopted abusive behaviour; prisoners showed submissiveness and distress.

• conclusion: powerful situational/role effects on aggressive and deindividuated behaviour.

• concept: used to illustrate deindividuation and situational power effects.

• exam link: “discuss deindividuation and situational determinants of aggression.”

eron et al. (1972) — TV aggression longitudinal study.

• aim: to examine long-term effects of childhood exposure to televised aggression on later aggressive behaviour.

• procedure: followed n ≈ 875 children from age ~8 to ~30; measured favourite TV programmes (aggressive content) and later adult behaviour.

• results: children who preferred more violent TV were rated more aggressive as adults (correlation ~ r = .18).

• conclusion: early exposure to aggression-model media is a long-term risk factor.

• exam link: “describe long-term observational evidence for media effects on aggression.”

baron (1977) — temperature and aggression.

• core idea: aggression increases with ambient temperature up to a point, then decreases — the “heat hypothesis.”

• aim: to test whether higher temperature leads to greater aggressive behaviour.

• procedure: participants in a car were stopped by a confederate at a green light; the duration of horn honking was measured across different temperatures.

• results: aggression (measured by horn duration) rose as temperature increased up to ~90°F (32°C), after which it declined.

• conclusion: situational factors like temperature trigger aggression, but extreme discomfort inhibits it (inverted-U effect).

• exam link: “explain how environmental factors can influence aggression using empirical evidence.”

berkowitz & lepage (1967) — weapons effect.

• aim: to examine whether the mere presence of aggressive cues (weapons) increases aggression.

• hypothesis: exposure to weapons primes aggressive responses.

• procedure: participants angered by shocks were then given the chance to deliver shocks back; in one condition, a gun was on the table, in another, a neutral object.

• results: average shocks delivered were significantly higher (mean = 2.67 vs 1.80) when a gun was present.

• conclusion: aggressive cues in the environment can activate aggression-related schemas even without direct provocation.

• exam link: “discuss how situational cues influence aggressive behaviour (weapons effect).”

Finding	Explanation
Core idea	Presence of a weapon increases aggression, even without intent to use it.
Correct study findings	Mean number of shocks delivered: - Low anger, no weapon ≈ 2 - High anger, no weapon ≈ 4.5 - Low anger + weapons present ≈ 2.2–2.5 - High anger + weapons present ≈ 6 (highest)
Conclusion	Weapons prime aggression → independent of personal traits.

zimbardo (1969) — deindividuation and aggression.

• aim: to explore how anonymity affects aggression.

• procedure: female participants asked to deliver electric shocks to another person; some wore hoods (anonymous), others had name tags.

• results: anonymous group delivered shocks twice as long (mean = 8.2 s vs 4.0 s).

• conclusion: deindividuation reduces self-awareness and increases situationally-driven aggression.

• exam link: “explain the role of deindividuation in aggressive behaviour.”

diener et al. (1976) — halloween study.

• aim: to examine naturalistic deindividuation effects.

• procedure: 1,352 trick-or-treating children observed; some were asked their name/address (individuated), others not; groups vs individuals were then observed taking extra sweets or money.

• results: 57% of anonymous groups transgressed vs 21% of identified individuals.

• conclusion: group anonymity and diffusion of responsibility increase antisocial aggression-like behaviours.

• exam link: “outline field evidence for deindividuation effects.”

bandura (1965) - modelling + vicarious reinforcement.

• aim: to examine vicarious reinforcement in aggressive imitation.

• procedure: children watched film where adult model = rewarded/punished/neither after aggressive acts toward a bobo doll.

• results: children imitated aggression more when the model was rewarded (mean = 3.5 acts (rewarded) vs 1.5 (punished)).

• conclusion: situational reinforcement contingencies shape aggression (people learn to be aggressive when they see that aggression works for them in a given context).

• exam link: “describe how reinforcement and imitation contribute to situational aggression.”

dodge (1980, 1986) — hostile attribution bias.

• aim: to explain why some individuals (especially children) perceive aggression in ambiguous situations.

• procedure: children shown videos of children in ambiguous provocation scenarios and asked why the other child acted that way.

• results: aggressive children interpreted ambiguous cues as hostile significantly more often (≈ 70% vs 30% in controls).

• conclusion: personal cognitive bias → predisposes aggression in ambiguous contexts.

• exam link: “explain the role of cognitive biases as personal determinants of aggression.”

DeWall et al. (2007) — self-control and aggression.

• aim: to argue for a comprehensive model where aggression is primarily viewed as a failure of self-control.

• procedure: literature review of studies manipulating self-control resources (eg: through depletion tasks or glucose administration) and measured subsequent aggression levels using experimental paradigms (eg: the noise blast task).

• results:

  • depletion-increased aggression: ptps whose self-control resources were experimentally depleted beforehand = exhibited significantly higher levels of aggression after provocation compared to control groups.

  • bolstering-decreased aggression: studies that bolstered self-control (eg: by providing sugary drinks containing glucose to restore brain energy/through self-control training interventions) found decreased aggressive responses.

• conclusion: self-control functions like a limited "muscle" or resource that is necessary to override aggressive impulses. resource is strong/fully charged = aggression is inhibited; resource is depleted = more likely to behave aggressively, especially when provoked.

giancola (2004) — alcohol and aggression.

• aim: to explore how alcohol affects aggressive responding.

• procedure: intoxicated vs sober participants engaged in competitive reaction-time task where winners could administer shocks.

• results: intoxicated participants delivered 30–40% higher intensity shocks and rated higher anger levels.

• conclusion: alcohol impairs cognitive control and increases situational aggression, especially when provoked.

• exam link: “explain how alcohol functions as a situational risk factor for aggression.”

hoaken et al. (2003) — executive dysfunction and aggression.

• aim: to test whether executive cognitive control deficits predict aggression under provocation.

• procedure: 60 male participants completed executive function tasks and aggression paradigms.

• results: individuals with low executive control showed 2× higher aggression scores.

• conclusion: personal neurocognitive traits contribute to aggressive behaviour when combined with situational triggers.

• exam link: “evaluate cognitive control deficits as personal determinants of aggression.”

cornell et al. (1996) — crowding and aggression (situational factor).

• aim: to test the link between density and aggression in prisons.

• procedure: compared inmate violence rates across prisons varying in crowding levels.

• results: high-density prisons showed 36% higher assault rates.

• conclusion: environmental stressors heighten aggression in social confinement.

• exam link: “discuss how situational stressors (e.g., crowding) contribute to aggression.”

buss (1961) — aggression machine paradigm.

• core concept: developed a controlled measure of aggression (electric shock paradigm).

• method: participants choose shock intensity for a “learner.”

• finding: aggression increased with provocation intensity.

• exam link: “identify classic laboratory paradigms used to measure aggression.”

staub (1989) — learning theory of violence.

• theory: violence is learned and maintained through reinforcement and social norms.

• application: societal violence (e.g., genocide) results from learned cultural acceptance.

• exam link: “describe how aggression can be learned at individual and cultural levels.”

baron & richardson (1994) — gender differences in aggression.

• finding: men show more direct physical aggression; women more indirect/relational.

• numerical result: mean aggression scores, 7-point scale— males = 4.6, females = 3.1.

• exam link: “compare gender differences in forms of aggression.”