Raine et al

• Background-Twin Studies

  • Lyons et al (1995)
  • studied records of misbehaviour & juvenile crime in 1,000s of twins
  • Monozygotic were not a lot similar to Dizygotic
  • suggests environment is important in determining criminal behaviour
  • found in adult criminals that aggressive behaviour was similar in MZ
  • suggests genetic factors become more important later on in life
• Aim: To study brain activity in murders and non-murders using positron emission tomography (PET) to find out whether there were differences in areas thought to be involved in violent behaviour
• Participants:

  • xperimental group= murders
  • 39 men & 2 women with a mean age of 34.3 years
  • each had been charged with murder or manslaughter
  • pleaded ‘not guilty by means of insanity’ but had been convicted
  • Control group= non murders
  • matched for sex and age
  • 6 participants schizophrenic
  • mean age did not differ from other group
  • no participants took medication for at least 2 weeks prior to testing
• Method:

  • Participants were brain scanned during a CPT
  • Chosen as it increases activity in areas of interest in normal participants
  • Participants were allowed to practice the CPT, 30 seconds before being injected with a fluorodeoxyglucose tracer for the PET scan and began their full CPT session
  • CPT continued for 32 minutes
  • PET images of 10 horizontal ‘slices’ through the brain were taken a 10mm intervals
  • scans were analysed for activity levels in many different brain areas
• Results:

  • murders had significantly less activity in lateral, medial and preictal prefrontal cortex areas of the brain compared to controls and corpus callosum.
  • had an abnormally asymmetrical activation in areas of the limbic system & lower activation in areas on the right in the temporal lode/hippocampus & thalamus
• Areas identified as having abnormal activity


  • Associated with aggressive behaviour
  • Associated with lack of fear
  • Associated with impulsiveness
  • Associated with problems with controlling & expressing emotions
• Abnormal brain activity


  Increased risk of committing acts of extreme violence
• Abnormal brain activity


  Problems with learning conditioned emotional responses
• Abnormal brain activity


  Failure to learn from experiences
• Abnormal brain activity in areas associated with learning

  Lower IQ
• Abnormal brain activity


  Lower chances of employment
• Abnormal brain activity


  Higher risk of criminality
• Abnormal brain activity appears to be one factor increasing the risk of committing a serious crime such as murder