Biological Classic Evidence - Raine

• Methodology - Raine aimed to investigate brain abnormalities in murderers who pleaded NGRI. This was a quasi-experiment with a matched pairs design. There were 41 murderers (2 women) who had a mean age of 34.3 years. They were referred to the University of California and all showed some form of mental impairment e.g 6 had schizophrenia, 23 head injury etc. For the procedures they all had to be medication free and urine scan 2 weeks prior.
• Methodology - a control group was made from matched pairs. This meant every murderer was matched with a normal individual who was of the same age and sex. The only one different was schizophrenic murderers who were also matched with 6 schizophrenics but were not murderers.
• Procedures - A PET scan was used to measure brain activity. All pps were given an injection/tracer (FDG) to take up active areas of the brain so it was possible to compare brains of NGRI and control group equally. All pps had to do a continuous performance task (CPT) so the investigators could see how different areas of the brain function.
• Procedures - Pps were given chance to practice CPT before FDG . 30 seconds before FDG pps started CPT. 32 mins after FDG PET scans were done on each participant. 10 slices/pictures were taken and recorded using cortical peel and box techniques. This was accurately recorded so the study could be replicated
• Findings - The study found REDUCED activity in the brain of NGRI in areas previously linked to violence e.g hippocampus, amygdala, thalamus. The study also found INCREASED activity in the brain of NGRI in areas not previously linked to violence e.g globus palidus, midbrain. For some there were no differences and for others there was reduced activity on left but more on right. All pps performed similarly on CPT therefore any brain differences were not related to CPT
• Conclusions - The study does provide evidence that murderers pleading NGRI have different brain functioning to normal individuals. However the results do not show violent behaviour is determined by biology alone as other factors e.g social play important roles. Results do not show that NGRI are not responsible for their actions or that PET scans should be used to diagnose violent individuals.