Aggression

• What is the limbic system made of?

  Hypothalamus

  Amygdala

  Hippocampus
• What is the role of the amygdala?

  Important predictor of aggressive behaviour

  If it is more responsive, there is more aggression

  Has a role in assessing and responding to environmental threats by evaluating emotional importance of sensory information and prompting an appropriate response
• What is Gospic et al (2011)?

  Participants were mildy provoked

  When participants showed aggression, fMRI showed fast and heightened amygdala activity

  Benzodiazepines taken had two effects:

  • Decreased amygdala activity
  • Decreased aggression
• What is the amygdala's link to aggression?

  Stimulation causes aggressive responses due to overly emotional response

  Kluver and Blucy - destruction of amygdalas of monkeys dominant in their group caused them to lose its dominant place
• What is the role of the prefrontal cortex?

  Associated with long term planning and anticipation of rewards
• What is the prefrontal cortex's link to aggression?

  If damages, impulses from the limbic system cannot be controlled for long term benefits
• What is the role of the hippocampus?

  Formation of long term memories - allows us to compare the conditions of a current threat with previous experiences
• What is the hippocampus's link to aggression?

  Impaired functioning means information can't be put into appropriate context and the amygdala may respond inappropriately to sensory stimuli, leading to aggression

  • Boccardi et al - violent offenders showed abnormalities in hippocampal functioning
• What is the link between serotonin and aggression?

  Inhibitory neurotransmitter exerts a calming effect of neural firing

  Normal levels in the orbitofrontal cortex are linked with decreased firing (greater behavioural control)

  Decreased serotonin disrupts the mechanism which reduces self-control leading to an increase in impulsive behaviour and aggression

  Virkkunen et al - compared serotonin breakdown product in cerebrospinal fluid levels in impulsive and non-impulsive offenders, levels were significantly lower in impulsives (greater breakdown, decreased serotonin levels)
• What is the research support for serotonin deficiency hypothesis?

  Mann et al - gave a drug to decrease serotonin, aggression rose, but only in males not females - Shows it is an incomplete explanation alone

  Duke et al - meta analysis, small inverse relationship for serotonin levels and aggression and hostility, magnitude varied with method of assessment, suggests relationship is more complex than originally thought

  Raleigh et al - monkeys on high tryptophan diet (increase serotonin) showed decreased aggression, and vice versa

  Rosado et al - aggressive dogs showed lower serotonin levels
• What is the research evidence of the role of the amygdala in aggression?

  Pardini et al - longitudinal study, lower amygdala volume lead to higher levels of aggression and violence

  The relationship between volume and aggression continued after confounding variables were controlled

  Suggests the amygdala plays a crucial role in evaluation emotional importance of sensory information, and lower volume leads to impaired ability and therefore violence is more likely
• What is Spolsky et al?

  Found removing the source of testosterone in different species resulted in lower aggression levels

  Synthetic testosterone injections lead to a return of aggressive behaviour
• What is Dabbs (1987)?

  Measured testosterone levels via saliva samples in violent and non-violent criminals

  Highest levels had a history of primarily violent crimes and those with low levels had committed non-violent crimes
• What are castration studies in hormonal links to aggression?

  Castration studies in animals have demonstrated how removal of the testes can lead to reductions in aggressive, therefore supporting the idea that testosterone is a cause of aggression
• What is Dolan (2001)?

  Found a positive correlation between testosterone levels and aggressive behaviour in UK male offenders in maximum security hospitals (history of impulsive violent behaviour)
• What was R v Smith?

  Smith threatened to kill a police officer and had nearly 30 previous convictions for violent crimes such as arson, assault, and had stabbed another barmaid

  These all coincided with her premenstrual phases
• What was R v English?

  Drove into her lover after an argument

  Lawyer argued that she had "an extremely aggravated form of premenstrual physical condition"

  The judge was satisfied the offense was committed under "wholly exceptional circumstances"
• What was the evalution of the R v Smith and R v English cases?

  Dr Clare studied over 500 women to determine the relationship between premenstrual condition and psychological health and said it was "doubtful PMT is causing aggressive behaviour"

  The idea of hormone levels causing aggression has implications for the judicial system and therefore the theory should be thoroughly researched before making any formal changes to legislation or other official areas
• What are the evaluation points for the hormonal theory of aggression?

  Aggression and dominance distinguishment needs to happen - Eisenegger

  Reductionist and deterministic

  Social and economic factors - Dabbs and Morris
• What is the conflicting evidence for hormonal mechanisms of aggression?

  There are correlations for testosterone levels and provocation and aggression levels in in prison inmates, however Bain (1987) found no correlation between testosterone levels and violent behaviour in offenders
• Why should there be a distinguishment made between aggression and dominance in the hormonal mechanisms theory for aggression?

  Aggression is the intent to cause harm, dominance is gaining or maintaining status over another

  Aggression may just be a type of dominant behaviour

  Eisenegger found women with higher testosterone levels acted nicer to establish themselves in certain situations - cognition and social factors influence behaviour, supports the idea of testosterone increasing status-seeking, not just aggression
• Why is the hormonal idea for aggression reductionist?

  Biology overlooks other factors such as social, economic, and cognition

  Dabbs and Morris - rich vs. poor boy both with high testosterone levels home from the army, poor boy more likely to get into trouble - testosterone is an incomplete explanation for aggression, experiences influence it too
• Why is the hormonal theory for aggression deterministic?

  Free will and cognition are ignored despite likely playing a significant role in aggressive behaviour

  Also assumes humans act primitively and have no control over their aggressive behaviour
• What does SLT involve?

  Observation of models

  Identification and high regard increase likelihood of imitation

  Vicarious reinforcement

  Self efficacy

  Mediational processes (attention, retention, reproduction, motivation)
• What was Bandura's bobo doll study?

  Those in the aggressive condition acted more aggressively

  Supports the idea aggression can be learnt through observation and imitation

  Also showed it can be learnt through cartoons and films
• What is the Rocky and Johnny study?

  Supports the role of vicarious reinforcement and learned aggression

  Rocky's behaviour was only imitated when positively reinforced by getting the toys
• What are the criticisms for Bandura's study?

  Bobo doll is designed to be hit

  Bobo doll is not living, so children may act differently towards a living thing

  Only explains aggression in children - low generalisability due to age-limited sample and task

  Lacks mundane realism and ecological validity - unlikely situation in real life, no insight into situation with people who may retaliate

  However a subsequent study found that when a real clown was hit, the behaviour was still imitated
• What are the applications for SLT in aggression?

  Watershed in the UK - Bandura found real and cartoon footage caused imitation of aggressive behaviour, so no violence on TV before 9pm when most children are in bed

  Interventions against aggression - ACT Against violence programme educates parents and others of the dangers of providing aggressive models and encourages providing positive models instead, Weymouth and Howe - after the programme, increase in positive parenting and discontinuation of physical punishment

  SLT can be used to decrease aggressive behaviour
• How does SLT apply to adults as well as children?

  Phillips (1983) - higher rate of homicides in the USA following a highly publicised boxing match
• How does SLT explain cultural differences in aggression?

  Aggression among !Kung San people is comparatively rare

  Childrearing practices of physical separation and distraction of children when aggressive rather than reward or punishment, aggression in adults is also avoided

  A lack of direct reinforcement and availability of aggressive models decreases the opportunity or motivation for aggression acquisition through social learning
• What are the 3 genetic factors for the genetic explanation of aggression?

  Twin studies

  Adoption studies

  MAOA gene
• What do twin studies suggest?

  Heritability accounts for about 50% of the variance in aggressive behaviour
• What did Coccano et al show?

  Male monozygotic and dizygotic twins

  Concordance rate of aggressive behaviour - 50% in MZ, 19% in DZ

  Concordance rate of verbal aggression - 20% MZ, 7% DZ

  MZ concordance not 100% - not a full explanation as 100% of DNA shared

  Androcentric - only male participants

  Significant difference between MZ and DZ percentages - must be a genetic link
• How are adoption studies used to look at the genetic link in aggression?

  Similarities between biological parents shows a genetic influence

  Similarities between adoptive parents shows an environmental influence
• What did Rhee and Waldman find?

  Meta analysis

  Genetic influence accounted for about 41% of variance in aggression which is mostly in line with the link found in twin studies

  Therefore a genetic link, but also environmental as it was only 41%
• What is the MAOA gene?

  Gene responsible for producing the MAOA enzyme so neurotransmitters are broken down into chemicals to be recycled or excreted

  Breaks down serotonin and adrenaline
• What did Brunner et al find?

  Dutch family with many male members involved in aggressive and violent crimes (rape, arson, assault)

  Were found to have abnormally low MAOA levels
• What did Caspi et al find?

  People with MAOA-L gene (low MAOA levels) were significantly more likely to exhibit anti-social behaviour

  But only if they were maltreated as children

  Therefore MAOA is an insufficient explanation alone
• What is the issue with the sampling of studies into genetic influence of aggression?

  Participants are those convicted, however many frequent aggressive offenders are not convicted, so the sample is a small minority of those regularly involved in aggressive behaviour - unrepresentative sample

  Those convicted of a one-time crime such as murder may have been otherwise fairly non-aggressive or violent

  May explain why there is often little to no evidence found of heritability for violence
• What are the difficulties in determining the role of genetic factors in aggression?

  More than one gene usually contributes to a behaviour

  Other non-genetic factors may interact with genetic factors (genetic influences environment and vice versa)

  E.g. Caspi et al