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Summary Psychology AQA Aggression Notes
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Psychology AQA Aggression Notes
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Neural and hormonal mechanisms in aggression.Neural – Papez + Maclean limbic system (hypothalamus, amygdala, hippocampus) to aggression. Amygdala important predictor of aggression as key role is to assess and respond to environmental threats. Gospic subjected participants to mild
provocation and measured response on an fMRI. When a benzodiazepine drug was taken before provocation there was decreased activity in amygdala and half the number of rejections. Normal serotonin levels in orbitofrontal cortex linked to
reduced firing of neurons and greater levels of self-control. Decreased serotonin leads to reduced self-control. Virrkunen compared levels of serotonin breakdown in the cerebrospinal fluid of violent impulsive and non-impulsive offenders. Levels
were lower in impulsive offenders. More research showing OFC activity rather than limbic system – reduced activity in those with psychiatric disorders ft aggression. Drugs that increase serotonin reduce levels of aggressive behaviour – shown in
study less likely to retaliate violently to insults in shock test.
Hormonal – testosterone – Male sex hormone involved in development of masculine ft. Men become more aggressive towards other men at time in development when testosterone is highest. Castration studies show that removing testes reduces
aggression. Dolan found positive correlation between testosterone and aggression in 60 offenders in UK max security hospitals. Progesterone – female hormone. Levels of progesterone vary during ovulation cycle and are lowest during and after
menstruation. Ziomkiewicz found a negative correlation between progesterone and self-reported aggression. Human behaviour more complex than animal behaviour – cannot be generalised. Animal studies confirm role of testosterone – rats
castration led to decreased mouse-killing behaviour. Mixed evidence – dual-hormone hypothesis claims that low cortisol levels must also be paired with high testosterone for aggression better predictor than testosterone alone.
Genetic factors of aggression.
Twin studies suggest heritability accounts 50% variance in aggression. Greater similarities between monozygotic twins if aggression influenced by genetics. Coccaro found concordance rates of 50% for monozygotic twins and 19% for dizygotic.
Similarities between adopted child and biological parents suggests genetic influences, similarity with adoptive parents suggests environmental. Rhee and Waldman carried out meta-analysis of adoption studies of aggression. Found genetic account
for 41% of variance. MAOA gene controls the production of enzyme that regulates serotonin. The low-activity variant results in low activity of the MAO-A enzyme, linked to high levels of aggression. Nicknamed ‘warrior gene’ as Lea and Chambers
showed MAOA-L variant possessed by 56% of Maori men. Brunner studied 28 men from Dutch family involved in impulsive aggressive violent crime. Had abnormally low levels of MAO-A. MAOA-L only related to adult aggression when combined with
early trauma. Frazzetto found association between higher levels of aggression and MAOA-L but only in those with trauma in early life. Strong evidence of diathesis-stress model.
- Support for role of the MAOA gene. Men with high-activity variant co-operative and made fewer aggressive moves in a money-distributing game. Study also showed that non-genetic factors crucial. Even those with low-activity variant
behaved co-operatively when they were made aware that others were behaving co-operatively.
- Mechanism unclear. Low-activity enzyme increase serotonin. Yet low levels believed to contribute to more aggression. May be more accurate to say disrupted serotonin. Shows limited explanation – not yet fully understood.
- Twin studies lack validity. Assumed that monozygotic twins treated the same (equal environments assumption), more so than dizygotic twins. Concordance rates may be inflated as a result. Aggression may not be as great as suggested.
The ethological explanation of aggression.
Suggests that the main function of aggression is adaptive. Aggression beneficial to survival as a defeated animal is not killed but instead forced to establish territory elsewhere, this reduces competition. Dominance achieved using aggression. Pettit
studied groups of young children and found that aggression played an important role in the development of dominance hierarchies. Lorenz observed that fights between same species produce little physical damage. Instead consists of ritualistic
signalling. Intra-species confrontations end with ritual appeasement displays. This is adaptive because if every aggressive encounter ended with death, that would threaten the existence of the species. An innate releasing mechanism is an inbuilt
process in the brain triggers FAP. An environmental stimulus triggers the IRM which releases a specific sequence of behaviours called fixed action patterns. Lea identified 6 key features of FAPs: unchanging behaviours, universal, unaffected by
learning, ballistic, single purpose, a response to a stimulus. Tinbergen researched male sticklebacks which are highly territorial during mating season. The sign stimulus is the sight of the red spot. Tinbergen presented sticklebacks with a series of
wooden models of different shapes. Regardless of shape, if model had red spot male would show signs of aggression. Tinbergen found that these FAPs were unchanging from one encounter to another. Once triggered it ran its course to completion.
- Twin and adoption studies show that there is a significant genetic component to aggression. Brunner identified the MAOA-L gene as being associated with aggression. These lines of research point towards an innate basis of aggression.
Aggression differs from one culture to another. reactive aggression more typical amongst white men in southern US due to ‘culture honour’. Culture can override innate predispositions.
- Four-year war during which male chimps killed all members from another group. Violence continued even when victims offered appeasement signals. Challenge’s view that same-species aggression is self-limiting.
- Lorenz’s original view of FAPs outdated. Hunt pointed out that FAPs are greatly influenced by environmental factors and learning experiences. Many ethologists now prefer the term ‘modal behaviour patterns’.
Evolutionary explanations of human aggression
Male sexual jealousy because of paternity uncertainty. Investment in offspring who do not share genes is waste of resources. Leaves father with fewer resources for own offspring. Men who could avoid cuckoldry were more reproductively successful.
Psychological mechanisms have evolved to support this, this drives the aggressive strategies men employ to retain partners and prevent them from straying. Wilson and Daly identified male retention strategies including direct guarding, and negative
inducement. Wilson asked women to report male retention strategies of their partner. Women who agreed with statements such as ‘He insists on knowing who you are with and where you are always’ were twice as likely to have experienced physical
violence. 73% needed medical attention and 53% said they feared for their lives. Bullying occurs because of power imbalance. Researchers traditionally viewed bullying as maladaptive behaviour. Ancestors may have used bullying as an adaptive
strategy increase of survival by promoting own health. Male bullying – Volk argued bullying characteristics attractive to females. Wards off rivals and is therefore naturally selected. Adolescent boys with reputation for being tough less likely to
experience aggression, can be top of a dominance hierarchy. Female bullying takes place within relationships as method of control. Bullying to secure partner fidelity, behaviour would be naturally selected as enhances reproductive success.
- Can explain gender differences. It is not adaptive for females to be physically aggressive as it puts her offspring at risk. Verbal aggression is more adaptive.
- Cultural differences. Kung San people nicknamed ‘harmless people’, aggression discouraged from childhood and therefore rare. Homicide rate for them is high. Contradiction may indicate biased observations by outsiders.
- Reduce aggression by addressing deficiencies. Anti-bullying intervention aims to increase cost of bullying and rewards of prosocial alternatives.
Biologically determinists. We are aggressive because of adaptations beyond our control. implies aggression is inevitable. Humanistic psychologists argue aggression is exercise of free will due to cognitive factors.
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