classic study: Raine

• NGRI


  Not guilty by reason of insanity
• Experimental group


  • 41 murders (39 men and 2 women), who had pled NGRI
  • 23 had brain damage
  • 6 had schizophrenia
  • 2 had epilepsy
  • 7 had other emotional or learning disorders
  • Weren't receiving any psychoactive medication for 2 weeks before the PET scans
• Control group


  • 41 age and sex-matched controls using PET scanning
  • Screened for their health by physical and psychiatric interviews
• Procedure

  1. Radioactive glucose tracer injected

  2. Participants completed Continuous Performance Task (CPT) for 32 minutes

  3. Participants given practice trials on CPT 10 minutes before injection

  4. Brain regions identified using Cortical peel Technique and Box Technique

  5. Raine measured relative amount of tracer in 4 brain lobes and 4 sub-cortical regions
• Procedure


  1. Radioactive glucose tracer injected

  2. 32-minute Continuous Performance Task (CPT)

  3. Practice trials on CPT 10 minutes before injection

  4. Transferred to PET scan room after 32 minutes

  5. Brain regions identified using Cortical peel Technique and Box Technique
• Raine measured the relative amount of tracer present in the 4 brain lobes and 4 sub-cortical regions
• NGRIS (Non-Guilty by Reason of Insanity)

  • Less activity in the frontal lobe especially the prefrontal cortex, associated with rational thinking and self-restraint
  • Less activity in the parietal lobe (abstract thinking, "morality")
  • More activity in the occipital lobe (vision)
  • Less activity in the corpus callosum
  • Activity imbalance between the two hemispheres
  • Less activity on the left hemisphere and more on the right in the amygdala
• On average the NGRIS corpus callosum activity was 0.56 compared to that of the control group (0.68)
• Prefrontal deficits


  Makes someone impulsive and emotional
• Corpus callosum deficits


  Brain hemispheres don't communicate as easily, making it harder to think of consequences
• Parietal lobe and amygdala deficits


  Make it harder for someone to judge social situations and to control urges and desires
• The sample used is the largest sample yet subjected to brain imaging (82)
• NGRIS are unusual as they don't remember killing or are too confused to stand trial, therefore they are unrepresentative of 'typical murderers'
• Not all the NGRIS killed their victims violently
• PET scans


  • Reliable techniques that have been used since the 1970s
  • Produce objective and replicable results
  • Test re-test can be used to check reliability
  • Results sometimes unclear and had to be interpreted by researchers
• The CPT (a standardised procedure) ensured that all participants were concentrating on the same thing, which makes sure that their brain activity was similar
• Raine didn't claim that PET scans can identify murderers or decide if someone is guilty or not
• Subjects participated under protocols and consent form approved by the Human Subjects Committee of University of California
• NGRIS agreed to have the PET scans as it would help their court cases
• If the NGRIS or the schizophrenic controls couldn't consent then presumptive consent was given by their lawyers/carers
• PET imaging is invasive and if it wasn't for the study, the controls wouldn't have gone through it
• Conclusions for a study like this may be misinterpreted, with employers "screening" potential job candidates to check they don't have a murderer's brain