aggression

• the role of the limbic system

  • network of structures including the amygdala, hippocampus & hypothalamus

  • amygdala - emotional centre - reactivity of amygdala important predictor of aggressive behaviour

  • hippocampus - forms long term memories - compare to past experiences
• evaluation of limbic system

  • support for amygdala - amygdalectomy reduces aggression in previously violent individuals - however side effects include loss of emotion & enthusiasm - doesn’t directly cause but is involved with aggression

  • support for hippocampus - MRI scans of violent offenders that were caught had different sized hippocampus - may have impaired ability of hippocampus & amygdala to work together leading to impulsive aggression
• the role of serotonin

  • widespread inhibitory effect

  • normal levels inhibits the firing of the amygdala

  • low levels remove this inhibitory effect so less able to control impulsive aggressive behaviour
• evaluation of role of serotonin

  • support - monkeys fed a diet high in tryptophan (increases serotonin levels) showed a decrease in aggression levels - monkeys fed diet low in tryptophan showed increased aggression

  • antipsychotic drugs that raise serotonin levels reduced impulsive aggression
• the role of testosterone

  • aggression higher in males than females so attention on the androgen group of hormones

  • basal model of testosterone - the more testosterone a person produces the more competitive and dominant they will become

  • dual hormone hypothesis - high cortisol = low testosterone
• evaluation of the role of testosterone

  • supporting evidence - measured testosterone in saliva of criminals - those with highest levels had history of violent crime

  • gender bias - most studies focussed on males & ignored females - testosterone could make women act nicer rather than aggressively - promotes status seeking behaviours
• genetic factors - MAOA gene

  • aggressive behaviour must be inherited

  • adoption, twin & family studies

  • MAOA regulates metabolism of serotonin - defective MAOA gene leads to low levels of serotonin = more difficult to inhibit emotional responses from amygdala leading to impulsive aggression
• evaluation of MAOA gene


  • support - found defective MAOA gene in dutch family with history of male violence

  • supporting evidence - disabled MAOA gene in mice & males became highly aggressive - restoring the gene returned mice to normal state

  • however cannot extrapolate

  • biologically reductionist - ignores environmental factors - bandura & bobo doll

  • biologically determinist - argues we are pre-programmed to be aggressive & have no free will over our aggression - negative implications for legal system
• ethological explanation

  • main function of aggression is adaptive

  • fights between same species i rarely result in physical damage - consist of ‘ritual’ signs & signals - excessive harm would damage species as a whole

  • all members of same species have stereotyped behaviours known as fixed action patterns (FAPs)

  • FAPs produced by inbuilt neural mechanism known as Innate Releasing Mechanism (IRM)

  • FAPs triggered by sign stimulus

  • e.g male stickleback fish
• what are the 6 main features of FAPs

  S - stereotyped

  U - universal

  U - unaffected by learning

  B - ballistic

  S - single purpose

  S - specific triggers
• evaluation of ethological explanation

  • supporting evidence - male stickleback fish

  • lack generalisability to humans - fail to acknowledge flexibility of human behaviour - we have ability to adapt so behaviour is not ‘fixed’

  • idea of behaviour patterns being ‘fixed’ been criticised - learning & experience interacts with innate factors to produce variations in behaviour - differ in durations of behaviours - replace term with ‘behaviour pattern’

  • idea of avoiding unnecessary harm also criticised - male lions kill off other males cubs & male chimpanzees kill members of another group
• evolutionary explanation


  • aggression evolved as help to solve challenges

  • aggression adaptive - solve conflicts e.g defending resources & eliminating rivals

  • sexual competition - males compete with other males (intra-sexual) - successful one would have increased social status & protected mate - pass on their aggressive genes to offspring

  • sexual jealousy - result of paternal uncertainty - always at risk of cuckoldry - use violence or threats to prevent female from straying
• evaluation of evolutionary explanation

  • offers plausible account of gender differences in aggression - female with offspring motivated to be less aggressive as would put her & offspring at risk

  • gender differences may be explained by socialisation - more likely to physically punish boys increasing male violence

  • deterministic

  • gender biased - alpha bias - exaggerate differences between males & females - found equal rates of aggressive assaults in families by women as there were by men
• frustration-aggression


  • argues frustration always leads to some form of aggression

  • catharsis - releasing strong or repressed emotions to produce relief

  • not getting something we want creates an aggressive drive leading to aggressive behaviour

  • displacement - aggression not always expressed directly against the source for 3 reasons: source may be abstract (e.g economy), too powerful & we risk punishment or unavailable at the time
• evaluation of frustration-aggression 


  • supporting evidence - when swedish football teams performed worse than expected, more objects were thrown onto pitch

  • evidence to suggest not all aggression rises from frustration - frustration only one of a large number of unpleasant experiences - as temp increased in baseball games, pitcher’s aggression would also increase - led to revised frustration-aggression hypothesis

  • evidence against catharsis - aggression likely to lead to more rather than less aggression in future - aggressive behaviour kept aggressive thoughts & feelings in memory
• social learning theory 


  • learning through observation & imitation

  • vicarious reinforcement

  • mediational processes

  • self-efficacy - if aggression is successful then the child has more confidence - may turn to aggressive to resolve conflicts in the future
• evaluation of social learning

  • support from bandura

  • scientific - however mediational processes not observable

  • practical applications - led to a watershed for TV
• de-individuation


  • a psychological state in which an individual loses their personal identity & takes the identity of the social group

  • frees the individual from their moral responsibility & social norms

  • factors contributing e.g anonymity, shared responsibility & intoxication

  • less fear of negative consequences in crowds & a reduced sense of guilty
• evaluation of de-individuation


  • support from zimbardo hooded electric shock study - groups of 4 female undergrads asked to deliver electric shocks to another student - 1/2 ppts wore hoods & 1/2 wore normal clothes - ppts in de-individuated condition shocked ppt twice as long

  • support from children on halloween - far more likely to steal money & sweets when they wore costumes & were in large groups

  • de-individuation can lead to pro-social behaviour - shocked less than control group when dressed in nurse uniforms
• dispositional explanation - importation model

  • institutional aggression a result of personal traits that prisoners bring with them into prison

  • prisoners are not ‘blank slates’

  • may come into prison with characteristics increasing their chances of violent behaviour e.g impulsivity

  • pre-prison gang membership is an important predictor of institutional aggression
• evaluation of dispositional explanation

  • practical applications - isolating known gang members in special management unit reduced rates of serious assault by 50%

  • criticising evidence - found gang members no more likely than other inmates to be violent suggesting aggressive tendencies not always ‘imported’
• situational explanation - deprivation model

  • institutional aggression a result of the prison environment - result of stressful & oppressive conditions & the deprivations of prisoners

  • deprivations:

  liberty - loss of freedom

  autonomy - no independence

  goods & services - lose access to material possessions

  heterosexual relationships - reduced self worth from lack of female company

  security - fear for their safety
• evaluation of situational explanation

  • practical applications - set up units that are less claustrophobic, have music & lower temp - virtually eradicated assaults

  • however analysis of 2 prisons in mississippi that allowed conjugal visits found no link between these visits & reduced aggressive behaviour
• research into effects of computer games on aggression

  • experimental research - lab experiment - students play either violent computer game or non violent game before asked to deliver blasts of white noise at chosen volumes - those played violent game selected higher noise levels

  • correlational study - interviews with juvenile offenders - offenders aggressive behaviour correlated with how often they played violent games

  • meta-analysis - violent video game use linked to increase in aggression & pro social games linked to pro social behaviour
• evaluation of research into computer games & aggression

  • high control over variables

  • correlational no cause & effect

  • practical applications - can encourage people to play specific types of games to increase pro-social behaviour

  • not measured real life aggression - administering noise blasts in place of real aggression which is very different & no fear of retaliation
• desensitisaction


  • repeated exposure to media violence removes the anxiety that normally inhibits aggressive behaviour

  • normally experience physiological arousal associated with sympathetic nervous system - repeated exposure leads to gradually less arousal so more likely

  to respond aggressively
• evaluation of desensitisation 


  • supporting evidence - ppts who reported regularly viewing violent media showed lower levels of arousal - low arousal correlates with unprovoked aggression in noise blast task

  • however doesn’t measure real life aggression - noise blasts very different to real aggression - furthermore correlation has no cause & effect
• disinhibition 


  • violent media undermines & loosens social constraints that normally inhibits aggressive behaviour

  • normally view violence as socially unacceptable

  • exposure to violent media can change these standards, creating new social norms

  • aggressive behaviour often made to appear normative & justified
• evaluation of disinhibition


  • support - ppts who watched a film depicting aggression as vengeance gave more electric shocks of longer duration - vengeance seen as a justification

  • however depends on other factors - children growing up with strong norms against violence unlikely to experience sufficient disinhibition whereas stronger for children who experience physical punishment
• cognitive priming 


  • temporary increase in accessibility of thoughts & ideas

  • exposure to violent media activates thoughts or ideas about violence which activate other aggressive thoughts

  • these thoughts more readily available

  • more likely to act aggressively in a situation of conflict shortly after

  • temporarily increases aggression
• evaluation of cognitive priming

  • support - undergrads watched 15 min segment of violent film - faster reaction time to aggressive words than those who watched non-violent film