Aggression

• What is an innate releasing mechanism

  • Built in physiological process : network of neurons in the brain that release sequenced behaviour
  • Triggered by an environmental stimuli
  • Behavioural sequence is called a fixed action pattern
• Lea proposed 6 features of fixed action patterns

  What are they?

  1. Stereotyped
  2. Universal
  3. Unaffected by learning
  4. Ballistic
  5. Single purpose
  6. Response to a specific stimulus
• What is a strength and a limitation of neural mechanisms in aggression

  • Strength:

  -Drugs that increase seretonin reduce levels of aggression

  -Bermon-> Gave ppts a placebo or a drug that increased seretonin

  -Found that the seretonin group gave fewer shocks than the placebo group

  -Evidence of causal link

  • Limitation:

  -Non-limbic structures also involved in aggression

  -amygdala and OFC function together ( OFC not in limbic system)

  -OFC activity is reduced in psychiatric disorders that feature aggression

  -Show neural regulation of aggression is more complex
• What is the role of the Obitofrontal cortex (OFC) & seretonin in aggression

  • Decreased seretonin in OFC results in reduced self-control and an increase in impulsive behaviour

  Virkunnen ->

  • Compared levels of seretonin breakdown product in cerebrospinal fluid of impulsive violent offenders & non- impulsive violent offenders
  • Found significantly lower levels of seretonin in impulsive violent offenders
• Name the 2 mate retention strategies and give examples

  1. Direct gaurding-> male vigilance over a partner's behaviour (e.g tracking them)
  2. Negative inducements-> issuing threats of dire consequence (e.g I'll kill myself if you leave me )
• Describe the evolutionary explanation of sexual jealousy

  • men can never be totally sure of they are the father of a child = paternity uncertainty
  • Threat of cuckoldry-> waste of resources on someone elses offspring & not passing on their own genes
  • Psychological mechanisms have evolved to increase anti-cuckoldry behaviour in males e.g employing mate retention strategies
• Describe what Wilson et al. found in relation to the link between mate retention strategies and physical violence

  • Women who reported mate retention strategies twice as likely to suffer physical violence at the hands of their partner:

  -73% required medical attention

  -53% feared for their lives
• What is one evaluation point of genetic factors in aggression?

  Research support for MAOA gene differences
• How do MAOA-H participants behave in a money distributing game?

  They are more cooperative and less aggressive
• What was observed about MAOA-L participants when informed of others' cooperation?

  They acted less aggressively
• What is the confusing link between the MAOA gene and aggression?

  Low serotonin levels usually lead to aggression
• What is the implication of MAOA-L on serotonin levels?

  MAOA-L should lead to higher serotonin levels
• How should serotonin regulation in people with MAOA-L be described?

  As disrupted rather than higher or lower
• What assumption is made about MZ and DZ twins in genetic studies?

  Equal environments are assumed
• How might people treat MZ twins differently than DZ twins?

  They may treat MZ twins more similarly
• Describe gene- environment interactions in aggression

  • MAOA-L gene activity only related to aggression when combined with early traumatic life events

  Frazetto: Found MAOA-L gene only increased aggression in those who had experienced significant trauma in first 15 years
• Describe the role of the MAOA gene

  • Controls production of MAO-A enyzme -> regulates seretonin
  • MAOA-L: Low activity variant of MAOA gene, linked to aggressive behaviour

  Brunner:

  • Studied 28 male members of large Dutch family
  • Repeatedly involved in violent criminal behaviour
  • Found these men had abnormally low levels of MAO-A and the MAOA-L gene variant
• Describe the role of genetic factors in aggression ( adoption studies)

  Similarities in aggressive behaviour of child and their:

  • Biological parent= genetic influences
  • Adoptive parents = environmental influences

  Rhee & Weldman:

  -Meta-analysis of adoption studies of direct aggression

  -Genetic variances accounted for 41% of variance in aggression
• Describe genetic factors of aggression ( twin studies)

  • Suggests heritability accounts for 50% of variance in aggressive behaviour
  • Coccaro: Studied adult male MZ and DZ twins
  • Found:

  -Concordance rate of 50% MZ

  -Concordance rate of 19% DZ

  for physical assault
• What is the role of the limbic system in aggression

  • Reactivity of amygdala is an important predictor of aggressive behaviour

  Gospic et al:

  -Ppts were subjected to mild provocation

  -When ppts acted aggressively, fMRI showed heightened response in the amygdala

  -Benzodiazepine: reduced amygdala & aggressive behaviour