Key Research - Raine

• What was the background?

  • Previous research shows violent offenders have poorer brain functioning compared to control group of normals
  • Did PET scans to localise which areas are dysfunctional in violent offenders
  • PET allows cross sections of the body to be displayed as images
• What was the aim?

  • Wanted to research brain dysfunction in violent offenders specifically those who commit murder and plead not guilty by reasons of insanity (NGRI)
• Hypotheses: Localised in brain previously associated with violence

  Amygdala – overactive = aggressive and underactive = aggressive / cold beh.

  Hippocampus – damage = impulsivity, unplanned murders

  Thalamus – changes in emotional reactivity and damage linked to combativeness

  Prefrontal cortex – poor behavioural control and damage = less self control and aggression

  Angular gyrus – reduced function = difficulty making sense of events and consequences

  Corpus callosum – why violent criminals can’t explain way out of threatening situations
• Hypotheses: No dysfunction

  • No dysfunction in others e.g. caudate, putamen and cerebellum – implicated in psychiatric conditions but not related to violence
• What was the design?

  • Quasi experiment
  • IV – murderer or not
  • DV – activity in brain regions on PET scan
  • Matched pairs
• What was the sample?

  • 41 murderers, 39m and 2f, mean age 34.3 years
  • All charged with murder or manslaughter and pleaded NGRI or incompetence to stand trial
  • To prove NGRI or diminished capacity to stand trial they were referred to Uni of California Brain Image Centre for examination
  • All ppts some had some form of mental impairment e.g. schizophrenia
  • Control group that had no history of mental health were matched to murderers by age and sex
  • 6 schizophrenic murderers matched to 6 schizophrenic non murderers etc.
  • Ppts asked to be medication free for 2 weeks prior
• What was the procedure?

  • Ppts gave consent with consent forms which was approved by human subjects committee at Uni of California
  • Ppts required to work for 32 mins on Continuous Performance Task (CPT) based around target recognition
  • Ppts able to practice CPT 10 mins before tracer injection
  • Started CPT 30 secs before glucose tracer injected so that novelty of task not labelled by glucose
• What were the materials?

  • Thermoplastic head holder that was modelled to each ppt to hold head still in scanner
  • CPT involved ppt searching targets on a screen and pushing button when they were detected – designed to stimulate prefrontal cortex as required for them to concentrate on targets
  • PET scan to study active brain and all ppts injected with glucose tracer taken up by active areas of the brain
• What were the results?

  • Murderers had reduced activity in prefrontal cortex, left angular gyrus and corpus callosum
  • Murderers had reduced activity in amygdala, thalamus and hippocampus in right hemisphere
  • No differences in caudate, putamen and midbrain associated with mental illness
  • Groups did not differ on any aspect of behavioural performance on the CPT
• What were the main conclusions?

  • Provides evidence that murders pleading guilty NGRI have different brain functioning from normal individuals
  • Neural processors linked to violence are complex and cannot be reduced to a single brain mechanism
  • Violence is probably best explained by the disruption of a network of interacting brain mechanisms
  • This disruption would not cause violent behaviour but predispose someone to violent behaviours
• What did the conclusions not show?

  • Violent behaviour being determined by biology alone and that social, psychological and situational factors play important roles for predisposition
  • Murders pleading NGRI are not responsible for their actions and PET scans can’t be used for diagnosing violent individuals
  • Brain dysfunction doesn’t cause violence and could be the effect of violence
• R : What makes a criminal?

  • Offers insight into physiological explanations of criminal behaviour in individuals who plead NGRI
  • Murderers have reduced activity in specific areas of the brain e.g. prefrontal cortex and left hippocampus explaining loss of self control and increased aggression
  • Damage to the amygdala could mean murderers less likely to perceive threatening situations as dangerous
  • Need to be cautious about assigning 1 specific area of brain in explaining violence and it is more of interaction with different areas and biosocial approach could predispose individual to violence