Key research: Raine

• Background


  • Wanted to find out if brain dysfunction is the reason why people commit violent crimes
  • Raine investigated the difference in brain function between criminals and non-criminals
  • These criminals had pleaded NGRI
• Aim

  • What health conditions could lead people to not be responsible for their crimes
• Sample

  • 41 criminals (39 m and 2 f) who had committed either murder or manslaughter
  • All had been referred for brain scanning to find evidence that they were NGRI for several reasons including:
  • Schizophrenia (6)
  • Head injury/brain damage (28)
  • Epilepsy (2)
  • Compared to 41 controls matched by age and gender - Schizophrenics matched with schizophrenic
• Procedure

  • Participants injected with a glucose tracer which would show the level of activity in different regions of the brain
  • Participants then had to complete a Continuous Performance Task (CPT) which involved indicating each time the number 'zero' appeared on the screen; the numbers visually degraded over time to require more effort of each participant's pre-frontal cortex
  • Lasted 32 mins
  • If region of the brain was active, it will use more glucose so there will be higher levels in the tracer
• Results

  • Compared to controls, NGRI showed:
  • Less activity in the pre-frontal cortex, the left amygdala and corpus callosum
  • More activity in the right side of the amygdala, the occipital areas and the right side of the thalamus
• Conclusion

  • Reduced brain activity in the pre-frontal cortex could explain impulsive behaviour and lack of self-control
  • The differences in the amygdala could support the theory that violence is due to unusual emotional responses and lack of fear