AO1

• Who conducted twin studies that showed the importance of genes?

  Christiansen
• How many pairs of twins did Christiansen find and where?

  3500 twin pairs in Denmark
• What did Christiansen find?

  Concordance rates for offender behaviour of 35 % for monozygotic male twins and 13 % for non-identical dizygotic twins (slightly lower rates for females)
• Christiansen‘s study included all twins born between 1880 and 1910 in a region of Denmark
• Who conducted a adoption study on the role of genes?

  Crowe
• What did Crowe find?

  Adopted children whose biological mother had a criminal record had a 50 % risk of having a criminal record by age 18 whereas adopted children whose biological mother didn’t have a criminal record only had a 5 % risk
• Who conducted a genetic analysis of almost 800 Finnish offender?

  Tiiihonen et al.
• What did Tiihonen et al. find?

  Two genes, MAOA and CDH13, may be associated with violent crime
• What does the MAOA gene do?

  Regulates serotonin in the brain and has been linked to aggressive behaviour
• What has the CDH13 gene been linked to?

  Substance abuse and ADHD
• Tiihonen et al.’s genetic analysis found hat about 5 to 10 % of all severe violent crime in Finland is attributable to the MAOA and Cdh13 genotypes
• What model can also be applied to genetic influence on offending?

  Diathesis stress model
• Evidence suggests there may be neural differences in the brains of offenders and non-offenders Much of the evidence in this area has involved individuals diagnosed with antisocial personality disorder.
• What is antisocial personality disorder (APD) associated with?

  Reduced emotional responses, a lack of empathy for the feelings of others and is a condition that characterises many convicted offenders
• Who conducted many studies of the APD brain?

  Raine
• What did Rain find through several brain-imaging studies?

  Individuals with antisocial personalities have reduced activity in the prefrontal cortex, the part of the brain that regulates emotional behaviour
• What did Raine et al. also find about grey matter?

  11 % reduction in the volume of grey matter in the prefrontal cortex of people with APD compared to controls
• What does recent research suggest about empathy in individuals with APD?

  They can experience empathy but do so inconsistently, unlike most people who experience it consistently
• Who did research on empathy response in offenders with APD?

  Keysers
• What did Keysers find?

  Their empathy response is controlled by mirror neurons and was only activated when they were explicitly asked to empathise
• What is a mirror neuron?

  A brain cell that activates both when you perform an action and when you observe someone else doing the same action. It plays a key role in empathy, allowing us to ‘mirror’ or ‘feel’ the emotions and experiences of others
• How does the empathy response in individuals with APD differ from that of a normal brain?

  The normal brain has the empathy response always ‘on’ while individuals with APD seem to have a neural ‘switch; that is usually turned off but can be turned on
• What does Keysers’ research suggest about APD individuals and empathy?

  They are not completely without empathy but do not activate it automatically like most people do
• Low activity in the prefrontal cortex is associated with what?

  Impulsivity and loss of control
• Shirtcliff conducted research which suggested that a smaller amygdala may be linked to a lack of empathy in offenders
• Fallon conducted a blind experiment where he analysed 70 MRI brain scans including schizophrenics, criminals and ’typical’ people. He identified 5 brains which he felt were psychopaths which were correct. In every brain, there was damage and reduced activity to the orbito-frontal cortex (morality and compulsive behaviour)
• What is the limbic system?

  A set of structures which combine higher mental functions and emotions into a single system (emotional nervous system)
• What does the thalamus do?

  Connects the central nervous system to the cerebral cortex by processing sensory and movement information
• What does the amygdala do?

  Distinguishes and processes emotions, especially fear, which can trigger the fight or flight response. It‘s involved in transferring new learning to the long term memory through reward, punishment or emotionally arousing stimulus, which means it’s responsible for the creation of episodic memories. There are links to aggression, some research suggests destruction of the amygdala can reduce aggression
• Who conducted a brain scan study on criminals charged with murder or manslaughter who pleaded not guilty by reason of insanity?

  Raine et al.
• Raine et al. studied 41 murderers (2 females) using a PET to highlight areas of brain activity. The results were compared to a matched age and gender control group. Found reduced activity for offenders in the pre-frontal cortex and corpus callosum, including abnormally in the thalamus and amygdala