Aggression

• What is Aggression


  - Attitudes or behaviours associated with a desire to dominate situations

  - Often involves the presence of anger and an intent for cause harm
• What neural mechanisms impact aggression

  - The Limbic System and Serotonin
• what is the Limbic System

  - Central part of the brain makes up of different brain structures

  - Located under the cerebrum
• What are the parts of the brain in the Limbic system

  - Olfactory Bulbs

  - Hippocampus

  - Amygdala

  - Hypothalamus
• How does the Amygdala influence Aggression

  - 2 amygdalae

  - They are involved in processing fear, anger and pleasure

  - Damage to the amygdala (brain trauma, atypical growth, tumor) wtf can cause increased levels of testosterone and make someone more likely yo be aggressive
• Explain Sumer Et also research Support for the Limbic System and aggression

  - 14 year old diagnosed with tumour in her Limbic System

  - Found on an MRI following investigation into epileptic seizures and aggressive anger/rage

  - After drug treatments 'normal' levels of aggression returned
• How is "The role of the Limbic System isn't clear" a drawback

  - The Limbic System is made of many components, and its not always clear which components are implicated, or whether its the interaction between components that is important in aggression
• How is "Correlational research" a drawback of the Limbic System and aggression

  - the link between brain abnormalities and violence is only correlational, which merely indicates a vulnerability to aggression as others with abnormalities do not always demonstrate violent behaviour

  - This means the link of causation isn't clear
• What is serotonin


  - Neurotransmitter linked with regulating cyclical body processes and contributing to wellbeing and happiness

  - responsible for maintaining mood balance
• How do Low levels of serotonin cause aggression

  - Leads to anxiety, depression and/or insomnia

  - This leads to aggression as it lowers our control over the Limbic System, and means we have less control over our emotional response
• How does high levels of serotonin cause aggression

  - Leads to agitations confusion, rapid heart rate, high blood pressure, mania

  - This lowers rationality, making us more likely to have an aggressive response
• What is usually prescribed to help manage aggression linked to serotonin

  SSRIs
• Explain Berman et also research Support for the effect of drugs on serotonin led aggression

  - Gave ppts either a placebo or a dose of a drug that enhances serotonin activity

  - ppts then took part in a lab based vame in which electric shocks of varying intensity were given and received in response to provocation

  - the drug group was less likely to give high intensity shocks than the placebo group

  - but this was only true of ppts who had a prior history of aggressive behaviour

  - partially supports low serotonin levels as a cause of aggression (bc increasing the levels lowered the aggressive response)
• What Hormonal mechanism is implicated in aggression

  Testosterone
• What is testosterone and where is it found

  - found in both sexes, but it is the male sex hormone

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• What causes aggression (testosterone)

  - increased testosterone levels

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• What are the 3 ways testosterone leads to aggression

  - When there are higher levels of aromatase (an enzyme that aids the metabolism of testosterone) = more testosterone is activated = emotional response by the amygdala = more aggressive response

  
  

  - Higher levels of testosterone = lowered activity in the prefrontal cortex (decision making centre) = reduced mediation in decision making = irrational aggressive responses

  
  

  - Low serotonin + high testosterone in CNS = significant effect on neural mechanisms involved in the expression of aggressive behaviour

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• Hiw is "Evidence of a Link between testosterone and aggression in humans is mixed" a drawback of testosterone led aggression

  - Carre and Mehtas Dual hormone hypothesis

  - claims that High levels of testosterone only lead to aggressive behaviour when cortisol levels are low

  - when cortisol levels are high, testosterones influence is blocked

  - Poppa et al comfitmed this hypothesis with their study of adolescent males

  - basically testosterone doesn't work alone
• What do you talk about for the Genetic Explanation for Aggression

  - Twin Studies

  - Adoption Studies

  - The MAOA gene

  - Gene environment interactions
• What do Twin Studies suggests about aggression

  - Heritability accounts for about 50%, of the variance in aggressive behaviour
• What did Coccoro et al find (Twin Studies aggression)

  - studies adult male MZ and DZ twins

  - Phsyical Aggression: CR of 50% for MZ twins and 19% for DZ twins

  - Verbal aggression = CR of 28% for MZ twins and 7% for DZ twins

  - We expect to find a higher CR for MZ twins as they share 100% of their genes

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• Adoption Studies and Aggression

  - Similarities between adopted children and their adoptive parents suggest that environmental influences are operating
• What did Rhee and Waldman Find (Adoption studies aggression)


  - meta analysis of Adoption studies of direct aggression and antisocial behaviour

  - Found that 41% of variance in aggression was account for by genetic influences

  - This is in line with the twin studies

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• What is the MAOA gene

  - breaks down neurotransmitters in the brain after a nerve impulse has been transmitted from one neuron to another

  - breaks down the neurotransmitter into constituent chemicals to be recycled for excreted

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• How does the MAOA gene lead to aggression

  - dysfunction in its operation may lead to abnormal activity of the MAOA enzym, which in turn impacts serotonin levels in the brain
• Explain how the Warrior Gene variant of MAOA leads to aggression

  - Low MAOA activity variant- associated with various forms of aggressive behaviour
• Explain Brunner et also research into the warrior gene


  - Studies 28 members of a large Dutch family who were repeatedly involved in impulsively aggressive violent behaviour

  - The men were found to have abnormally low levels of MAOA and the low activity variant of the MAOA gene
• Explain the Warrior Gene and the environment

  - The low actuvity MAOA gene variant is only related to adult aggression when combined with early traumatic life events
• Explain Frazzetto et also research into gene environment interactions in aggression


  - Found an association between higher levels of antisocial aggression and the low activity MAOA gene in adult males, but only in males who experienced significant trauma before the age of 15

  - those without the trauma were not as aggressive, even if they had the low activity variant
• How is "Inability to isolate genetic factors" a drawback of the genetic explanation for aggression

  - It's very difficult to establish how influential genes are in aggressive behaviours

  - researchers have found difficulty separating genetic and environmental factors

  - An individual may possess a gene associated with aggression, but the behaviour is only expressed if environmental conditions are favourable

  
  

  - McDermott et al - ppts with the low activity MAOA gene behaved aggressively in a lab based money allocation game, but only when they were provoked, otherwise they were no more or less aggressive than other participants
• How is "Multiple Genetic Influences" a drawback of the genetic explanation for aggression (Stuart et al and Vassos et al)

  - The sizes of genetic effects are statistically significant, but also small

  - This means there are probably other genes involved in aggression

  - Stuart et al - Found that intimate partner violence was associated with the warrior gene and the serotonin transporter gene

  - Vassos et al - meta analysis - found no evidence of an associated between any one gene and aggression

  
  

  - This all suggests that aggression cannot be reduced doesn to one gene
• How is "Differing measures of aggression" A drawback of the genetic explanation

  - In different studies, the methods of measurement vary

  - Includes self reports, parent and teacher reports and direct observations

  - In one meta analysis, the researchers found that of 52 twin and adoption studies, genetic factors had a greater influence on aggression than in studied using self reports instead of parent teacher reports
• Ethological explanations suggest the main function of aggression is...

  adaptive
• Why is aggression adaptive according to the ethological explanation

  - Because it encourages defeated animals to establish territory elsewhere, allowing members of a species to spread out over a wider area

  - this reduces competition pressure
• How does aggression establish dominance hierarchies

  Gregory Pettit et al -

  - observed play groups of young children and identified aggression to play an important role in the development of some children's dominance over others

  - dominance brings benefits such as access to resources and the power to get your own way
• Who observed ritualistic aggression

  Lorenz
• What is Ritualistic aggression + APPEASEMENT DISPLAYS

  - Behaviours carried out in a set order

  - In many fights of animals in the same species, Lorenz observed very little actual physical violence, but more ritualistic factors

  - He also pointed out that aggressive confrontations end with appeasement displays

  - e.g wolves expose their necks to the victor, making themselves vulnerable to a single bite to its jugular vein
• How are appeasement displays adaptive


  - if every confrontation ended with death, this would threaten the existence of the species
• What is an Innate releasing mechanism

  - Built in physiological process e.g a network of neurons in the brain
• What stimulus triggers an innate releasing mechanisms

  environmental