Bio exp: Genetic and neural exp

• Types of genetic explanations

  • Twin studies
  • Adoption studies
  • Candidate genes
  • Diathesis stress model
• Genetic explanation?

  • Suggests that offenders inherit a gene or combination of genes that predispose them to commit crime
• Twin study research evidence?

  • Johannes Lange
  • Studied 13 MZ and 17 DZ twins
  • One of each pair served time in prison
  • FOUND: 10 of MZ but only 2 DZ also had a co-twin in prison
  • Concludes that genetic factors are likely a factor in offending behaviour and predisposition to crime
• What are limitations of twin studies, especially Johannes Lange's?

  • Most likely androcentric and looking at male behaviour due to the context of 1930s research, MZ twins will be the same gender
  • Twins are usually brought up in the same environment, it is assumed their environments are identical
  • It can be argued that MZ twins experience an even more similar environment than DZ twins
  • By looking similar they tend to be treated more similarly by their parents as well as their social groups therefore may explain the co-twin prison rate being higher
• Adoption study research evidence?

  • Crowe (1972)
  • Adopted children who had a biological parent with a criminal record had a 50% risk of having a criminal record by the age of 18.
  • Adopted children whose mother didn’t have a criminal record only had a 5% risk.
  • Therefore suggests that genes play a large part in offending
• Limitations of adoption studies including Crowe's?

  • Age of adoption can be very important as if the child was impacted by their biological mother’s criminal behaviour, then that would be an environmental factor not genetic
  • It could be a socially sensitive in the way that findings are reported and there may be negative consequences for adopted children especially
  • (e.g. not being able to be adopted until a certain age)
• Research support for candidate genes?

  • Jari Tiihonen et al
  • analysed up to 900 offenders
  • revealed abnormalities on two genes that may be associated with violent crime.
  • MAOA gene and CDH13
  • Within the Finnish sample, individuals with this high risk combination were 13 times more likely to have a history of violent behaviour.
  • However this research has not been replicated.
• Describe the MAOA gene Jari Tiihonen found

  • controls dopamine and serotonin and has been linked to aggressive behaviour)
  • Therefore this gene may increase vulnerability to increased aggressive and criminal behaviour, a genetic factor in offending
• Describe the CDH13 gene Jari Tiihonen found

  • Linked to substance abuse and attention deficit hyperactivity disorder
• Diathesis-stress model in criminal behaviour research support?

  • Mednick (1984)
  • Large scale of 13,000 adoptees.
  • if neither biological or adoptive parents have convictions then only 13.5% of the adoptees did.
  • If either of biological parents had convictions, 20% of adoptees did.
  • If adoptive and biological parents had convictions, this rose to 24.5% of adoptees
• What does Mednick's research for the diathesis stress model suggest?

  • The experience of adoption alone may be a factor in offending.
  • In each case this is further aggravated by environmental factors.
  • The diathesis is the predisposition of biological or adoptive parents’ criminal conviction record and the stress may be the environment of being adopted/growing up in a poor environment through childhood.
• Limitations of the diathesis stress model as an explanation?

  • Many children experience late adoption, which means much of their infancy is spent with their biological parents anyway
  • May mean that being adopted is less of a triggering factor and it is merely the experience of being brought up with criminal parents
• Types of neural explanations

  • Prefrontal cortex research
  • Limbic system
  • Mirror neurons
  • Neurotransmitters
• Neural explanation?

  • any explanation of behaviour and its disorders in terms of dysfunction. This includes the activity of brain structures such as the hypothalamus.
• Research support for the prefrontal cortex?

  • ADRIAN RAINE
  • Conducted many studies of the APD brain, concluding that antisocial personalities have reduced activity in the prefrontal cortex (this regulates emotional behaviour and moral behaviour).
  • Lower activity is associated with impulsiveness and loss of control.
• What did Raine's 2000 study find?

  • RAINE (2000) 11% reduction in volume of grey matter in the prefrontal cortex of people with APD compared to controls.
  • Suggests APD sufferers lack grey matter and may impair their ability to regulate social and moral behaviour
  • Increased vulnerability to crime
• What did Raine's 2004 study find?

  • RAINE (2004) cited 71 brain imaging studies showing that murderers, psychopaths and violent individuals have reduced functioning in the prefrontal cortex
  • Therefore APD sufferers may lack emotional and moral cognition, resulting in a lack of guilt/apathy for others
  • May lead to criminal behaviour
• Research support for the limbic system? (AO3)

  • RAINE ET AL (1997)
  • studied murderers who were found not guilty by reason of insanity (NGRI), compared with matched controls
  • Found abnormal asymmetries in the limbic system of the murderers.
  • There was reduced activity on the left and increased activity of the right.
  • May suggest that this leads to a larger vulnerability to criminal behaviour due to the lack of emotion and motivation
• What is the limbic system?

  • A group of subcortical structures including the thalamus and the amygdala (which are linked to emotion and motivation).
• Mirror neuron research support?

  • Criminals with APD are able to experience empathy but more sporadically than the rest of us
  • CHRISTIAN KEYSERS
  • Found only when criminals were asked to empathise (with a person depicted on film experiencing pain) did their empathy reaction activate. (controlled by mirror neurons within the brain).
  • Therefore, APD individuals are not without empathy but may have a neural ‘switch’ that can be turned on and off
  • unlike the ‘normal’ brain which has empathy switch permanently on.
• Neurotransmitter support for low levels of serotonin?

  • SEROTONIN -> SEO ET AL (2008)
  • low levels of serotonin may predispose individuals to impulsive aggression and criminal behaviour as this normally inhibits the prefrontal cortex.
  • Dopamine hyperactivity may enhance this effect.
• Neurotransmitter support for low and high levels of noradrenaline?

  • NORADRENALINE -> WRIGHT ET AL (2015)
  • Both very high and very low levels have been linked with aggression, violence and criminality.
• How noradrenaline linked to criminality?

  • High levels of noradrenaline are associated with activation of the SNS and the fight or flight response so are linked to aggression.
  • Noradrenaline also helps people react to perceived threats, so low levels would reduce this ability.
• Issues and debates topics as evaluation?

  • Biologically deterministic in research
  • Nomothetic approach
  • Levels of explanation, lowest level breaking it down into simplest biological parts – criminality may make more sense when looked at from a wider social Cultural perspective
  • Nature due to the focus on neurological structures and humans’ innate predisposition, may suggest criminals cant get better as you cant change brain structures