Aggression: Limbic System, Testosterone, MAOA, Ethology, Institutional & Media

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Neural and Hormonal Mechanisms in Aggression

1. The limbic system (Amygdala): The amygdala assesses environmental threats and triggers reactive emotional aggression. Gospic et al. (2011) scanned participants playing the Ultimatum Game using fMRI: when unfair offers were rejected aggressively, amygdala activity spiked, and administering the benzodiazepine drug midazolam halved both amygdala reactivity and aggressive rejections. Pardini et al. (2014) also showed lower amygdala volume at age 26 predicted future violence. 2. Serotonin & the orbitofrontal cortex (OFC): The OFC exerts rational self-control (top-down inhibition) over the amygdala's aggressive impulses. Normal levels of the neurotransmitter serotonin maintain high OFC firing; Low serotonin reduces OFC self-control, unleashing impulsive reactive aggression (supported by Virkkunen et al. 1994 finding lower serotonin metabolite 5-HIAA in impulsive arsonists/violent offenders, and Berman et al. 2009 showing the SSRI paroxetine reduced lab shock aggression). 3. Testosterone: An androgen hormone (10x higher in men than women) that promotes status-seeking and dominance: Dolan et al. (2001) found a positive correlation between testosterone and aggression in UK maximum-security prisoners, and Carre and Olmstead (2015) proposed the dual-hormone hypothesis - high testosterone only drives status-seeking aggression when the stress hormone cortisol is simultaneously low.

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Genetic Factors in Aggression: Twin Studies & The MAOA Gene

Twin and adoption studies show around 50% of the variance in aggressive antisocial behaviour is genetic: Coccaro et al. (1997) found a 50% MZ concordance vs 19% DZ concordance for physical assault, and Rhee and Waldman's (2002) meta-analysis of 51 twin/adoption studies confirmed a 41% heritability estimate. The most famous candidate gene is the MAOA gene (Monoamine Oxidase A, nicknamed the 'warrior gene'), which codes for the enzyme that breaks down excess serotonin, dopamine, and noradrenaline in the synapse after transmission. Brunner et al. (1993) studied 28 male members of a large Dutch family with a history of impulsive violence, arson, and attempted rape, finding they all shared a mutation shutting down MAOA production. In the wider population, Caspi et al. (2002) proved a diathesis-stress interaction: boys carrying the low-activity MAOA-L variant only grew up to be violently aggressive if they were also subjected to severe childhood maltreatment/abuse.

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Ethological and Evolutionary Explanations of Aggression

1. Ethological explanation (Konrad Lorenz 1966 'On Aggression'): Ethology studies innate animal behaviour in its natural environment. Lorenz argued intraspecific aggression (within the same species) is adaptive - it disperses territory/food, establishes dominance hierarchies, and selects strong mates without killing rivals because animals use ritualistic aggression (threat displays and appeasement gestures, e.g., a defeated wolf exposing its jugular vein to inhibit the victor's bite). Tinbergen (1951) showed aggression is triggered when a specific external sign stimulus activates an innate releasing mechanism (IRM - a built-in neural circuit), which unleashes a fixed action PATTERN (FAP - a stereotyped, universal, ballistic sequence of aggressive behaviours that cannot be stopped mid-stream, demonstrated when male three-spined sticklebacks attacked any wooden model with a red underbelly regardless of shape). Evaluation: Goodall (2010) disproved Lorenz's claim that animal aggression is harmless ritual by observing the 'Gombe Chimpanzee War', where male chimps systematically slaughtered every member of a rival troop despite appeasement gestures. 2. Evolutionary explanations: Male sexual jealousy (paternity uncertainty) drives mate retention strategies - Direct Guarding (vigilance over partner's whereabouts) and Negative Inducements (threats of violence for infidelity), which Shackelford et al. (2005) found correlated strongly with intimate partner violence.

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Social Psychological Explanations: Frustration-Aggression & Deindividuation

1. Frustration-aggression hypothesis (Dollard et al. 1939): Grounded in psychodynamic catharsis, it claims frustration always leads to aggression and aggression is always caused by frustration. When a goal-directed behaviour is blocked, an aggressive drive builds up; if the true source of frustration is too powerful, abstract, or absent, aggression is displaced onto a weaker, available scapegoat (demonstrated in Green's 1968 jigsaw-puzzle study). Berkowitz (1969, 1989) revised this: frustration merely creates an emotional readiness (anger) to be aggressive, which only turns into actual aggression if environmental aggressive cues are present (demonstrated by Berkowitz & LePage's 1967 'Weapons Effect', where angry participants gave significantly more shocks when a shotgun and revolver were lying on a nearby table vs badminton racquets). 2. Deindividuation (Zimbardo 1969; Prentice-Dunn & Rogers 1982): When immersed in a crowd, uniform, dark room, or online anonymity, people lose their personal identity and stop monitoring their own internal moral standards (reduced private self-awareness) and stop caring about societal evaluation (reduced public self-awareness). Demonstrated in Zimbardo's (1969) hooded vs name-tagged female shock study, though Gergen et al.'s (1973) 'deviant in the dark' room showed deindividuationactually leads to conformity to local group norms (prosocial/intimate in a dark room, or helping in a nurse uniform in Johnson & Downing 1979).

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Institutional Aggression in Prisons: Importation vs Deprivation Models

Why is violence so common inside prisons? 1. The importation model (Irwin & Cressey 1962 - Dispositional): Prisoners are not 'blank slates' when they walk through the prison gates, they IMPORT their pre-existing violent subcultural norms, gang affiliations, criminal beliefs, traumas, and substance dependencies from the outside street into the prison to negotiate status and power (supported by DeLisi et al. 2004, who studied 813 juvenile delinquents and found pre-existing gang membership and trauma strongly predicted prison violence). 2. The deprivation model (Sykes 1958 - Situational): Prison violence is caused by the harsh institutional environment itself, specifically five 'pains of imprisonment' - deprivation of liberty, autonomy, goods and services, heterosexual relationships, and security, alongside overcrowding and unpredictable regimes, which create frustration and violent competition for scarce resources (supported by Steiner 2009 across 512 US prisons, and Richard McCorkle et al. 1995, plus David Wilson's 2004 HMIP study at HMP Woodhill where reducing heat, noise, and isolation virtually eliminated assaults on staff).

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Media Influences on Aggression: Desensitisation, Disinhibition & Cognitive Priming

Longitudinal and experimental studies (Anderson & Dill 2000; Robertson et al. 2013 across 1,000 New Zealand children; Bartholow & Anderson 2002 using the Taylor Competitive Reaction Time 'noise-blast' task) link violent television and interactive video games to heightened aggression via three mechanisms: 1. Desensitisation (Carnagey et al. 2007): Repeated exposure to graphic screen violence habituates the sympathetic nervous system, reducing physiological arousal (lower heart rate and skin conductance) and empathy when witnessing real-life violence. 2. Disinhibition (Berkowitz & Alioto 1973): Normally, social norms inhibit aggression; violent media weakens these restraints by portraying violence as justified, socially acceptable, and heroic ('vengeance with no guilt'), particularly in video games where players are directly rewarded with points for killing. 3. Cognitive priming (Huesmann 1998): Violent media provides ready-made aggressive 'scripts' stored in long-term memory that are automatically triggered (primed) whenever the viewer encounters a real-life interpersonal conflict (supported by Fischer & Greitemeyer 2006 on aggressive song lyrics).

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1. Q1

   Outline and evaluate neural and hormonal mechanisms in aggression. (8 marks)

   Check Mark Scheme

   Click “Check Mark Scheme” to compare your answer, 1. [AO1 - 4 marks] Neurally, the limbic system (specifically the amygdala) drives reactive threat assessment and emotional aggression, while the orbitofrontal cortex (OFC) exerts top-down inhibitory self-control over the amygdala. Normal levels of the neurotransmitter serotonin sustain OFC activity; low serotonin reduces OFC inhibition, unleashing impulsive aggression. Hormonally, the androgen testosterone (regulated by the endocrine system) promotes dominance and status-seeking aggression, especially in interaction with low cortisol (the Dual-Hormone Hypothesis, Carre & Olmstead 2015). 2. [AO3 Support for Neural Mechanisms - 2 marks] Gospic et al. (2011) used fMRI during the Ultimatum Game to show that rejecting unfair offers aggressively correlated with heightened amygdala activity (which the calming drug midazolam halved), and Berman et al. (2009) showed that boosting serotonin with the SSRI paroxetine significantly reduced laboratory shock aggression compared to placebo. 3. [AO3 Evaluation of Hormonal Mechanisms - 2 marks] Dolan et al. (2001) found a positive correlation between testosterone and aggression in maximum-security prisoners, and animal castration/injection studies confirm causality; however, Mazur (1985) pointed out that testosterone is more accurately linked to social dominance (non-violent status-seeking) than physical violence, and human studies are correlational.

2. Q2

   Discuss the ethological explanation of aggression, including reference to innate releasing mechanisms and fixed action patterns. (8 marks)

   Check Mark Scheme

   Click “Check Mark Scheme” to compare your answer, 1. [AO1 - 4 marks] Proposed by Konrad Lorenz (1966), ethology views intraspecific aggression as an adaptive instinct that aids survival by dispersing resources, establishing dominance hierarchies, and selecting fit mates. Lorenz argued animals rarely kill members of their own species because evolution favoured ritualistic aggression (threat displays and appeasement signals like a wolf exposing its neck). Aggression is triggered when an environmental sign stimulus activates an Innate Releasing Mechanism (IRM - a hardwired neural circuit), which unleashes a Fixed Action Pattern (FAP): a stereotyped, universal, ballistic sequence of behaviours independent of learning (illustrated by Tinbergen's 1951 male sticklebacks attacking any wooden model with a red spot). 2. [AO3 Strength: Evolutionary insight and genetic/neural basis - 2 marks] Tinbergen's controlled experiments demonstrated clear innate stimulus-response patterns in lower animals, and human universal facial expressions of anger support an innate evolutionary component. 3. [AO3 Limitation: Goodall's chimpanzee war & cultural differences in humans - 2 marks] Jane Goodall (2010) refuted Lorenz's claim that intraspecific animal aggression is harmless ritual by documenting the 4-year Gombe Chimpanzee War, where male chimps brutally cannibalised and exterminated a rival group despite appeasement gestures; furthermore, Nisbett (1993) showed huge cultural differences in human homicide rates (e.g., US Southern 'culture of honour' vs Northern states), proving human aggression is heavily shaped by learning and culture rather than rigid FAPs.

3. Q3

   Compare the Importation Model and the Deprivation Model as explanations of institutional aggression in prisons. (6 marks)

   Check Mark Scheme

   Click “Check Mark Scheme” to compare your answer, 1. Outline of Importation Model (Irwin & Cressey 1962): A dispositional explanation arguing that inmates bring their pre-existing violent subcultural values, gang loyalties, substance abuse, and histories of trauma into the prison from outside and use violence to establish status [2 marks]. 2. Outline of Deprivation Model (Sykes 1958): A situational explanation arguing that the harsh, oppressive conditions of the prison environment itself, specifically the five 'pains of imprisonment' (loss of liberty, autonomy, goods/services, heterosexual relationships, and personal security) alongside overcrowding, create frustration that erupts into violence [2 marks]. 3. Research Evaluation & Synthesis: DeLisi et al. (2004) supported Importation by showing pre-existing gang membership predicted prison violence (though Camp & Gaes 2005 found this disappeared when inmates were placed in well-run prisons), whereas Steiner (2009) and Wilson's (2004) HMP Woodhill reform (where reducing noise, heat, and isolation eliminated assaults on staff) strongly support Deprivation; modern criminologists adopt an interactionist view (Jiang & Fisher-Giorlando 2002) that imported traits interact with situational deprivations [2 marks].

4. Q4

   Evaluate research into the influence of computer games and violent media on aggression. Refer to methodological issues in your answer. (6 marks)

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   Click “Check Mark Scheme” to compare your answer, 1. Experimental Support & Artificiality (Low Ecological Validity): Lab experiments like Anderson and Dill (2000) and Bartholow and Anderson (2002) show playing violent games (Wolfenstein 3D / Mortal Kombat) increases white-noise blasts delivered to an opponent compared to non-violent games (Myst / Tetrix); however, pressing a noise-blast button in a lab has zero fear of retaliation and lacks ecological validity as a measure of real-life physical violence [2 marks]. 2. Longitudinal Support vs Direction of Causality: Correlational and longitudinal studies (Robertson et al. 2013 tracking 1,000 New Zealand children over 20 years) found childhood screen time predicted adult criminal convictions, yet correlational designs cannot rule out reverse causation (naturally aggressive people simply prefer violent games) [2 marks]. 3. Confounding Variables & Publication Bias: Ferguson (2007, 2015) demonstrated that when studies failed to control for confounding variables such as game difficulty/frustration (Przybylski et al. 2014 showed losing a hard game of Tetris caused just as much frustration-aggression as a violent shooter) or family violence, the effect of violent content itself shrank to near zero, alongside evidence of publication bias against null findings [2 marks].

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