Classic study: Raine et al. (1997)

• Aim

  • To investigate if there were brain differences between violent offenders and non-offenders.
  • To see if people who had committed murder had brain dysfunction in certain areas of the brain.
• Procedure - matched pairs design:

  1. Experimental group - 41 murderers who had pleaded NGRI, 39 females and 2 females, had a range of diagnosis' (schizophrenia/brain damage).
  2. Control group - 41 ppts matched on age, sex and ethnicity, 39 males and 2 females.
  3. Screening process for control group - medical records accessed, physical examination and psychiatric interview (6 had schizophrenia). Excluded if they had experienced head trauma/a history of seizures or substance abuse.
• All participants

  • Medication/drug free for 2 weeks prior.
  • Gave consent for brain scan.
  • Carried out same continuous performance task (recognising blurred number sequence) while having PET scan.
  • PET scan - measure metabolic rate in brain areas; shows which part of brain is more or less active during tasks.
• Results

  • No difference in the performance of the task between the two groups.
• Results - statistically significant differences in glucose metabolism

  • Cortical areas: lower activity - lateral and medial prefrontal areas, left angular gyrus, left and right superior parietal areas. Higher activity - occipital lobe.
  • Subcortical areas: lower activity - corpus collosum, left amygdala, left medial temporal. Higher activity - right amygdala, right medial temporal lobe, right thalamus.
• Conclusion

  • Murderers pleading NGRI have different brain activity compared to non-violent offenders.
  • Murderers had impaired functioning in areas of the brain perviously identified as involved in violence.
  • Dysfunction of a brain area cannot explain violence on its own.
  • Most likely explanation is that networks of interacting brain areas are functionally impaired.