“raine et al. (1997) Brain abnormalities in murderers indicated by positron emission tomography”
— Specification code 3.3.1
Key things in this study:
- Biological cause of aggression
- Brain structure
- PET scans
AO1
Aims
- To investigate whether there was difference in brain functioning of murderers who pleaded NGRI (not guilty by the reason of insanity), compared to non-violent people.
Procedure
- The sample contains 41 murderers (39 males and 2 females) who pleaded NGRI (not guilty for the reason of insanity), and 41 control participants.
- A matched pair design is used. Participants are matched for age and sex. All participants are medication free.
- The participants were injected with a glucose tracer. They were required to work at a continuous performance task (CPT). After this, a PET scan is given.
- The participants were also allowed to practice the CPT ten minutes before the injection.
- The PET scan measured the activity of different regions of the brain.
Results
- NGRIs had less activity in their prefrontal cortex
- NGRIs had less activity in their parietal lone
- NGRIs had more activity in their occipital lobe
- NGRIs had less activity in thier corpus callosum
- NGRIs had an imbalance of activity between the two brain hemispheres, for the amygdala, hippocampus, and thalamus.
Conclusions
- Violence and aggression cannot be attributed to a single brain region, as multiple areas seem to be involved.
- There is a link between brain activity and violent behavior.
AO3
Strengths
A matched pair design is used
Weaknesses
Cannot show cause and effect
One weakness of Raine’s study is that the study cannot show brain deficits is the cause of violent or aggressive behavior. For example, the NGRIs might have developed their brain deficits after committing the crime. This could be due to stress from the event, their arrest, imprisonment, and upcoming trial. This is a weakness because the cause and effect relationship between brain deficits and violence is unclear, and may not be a valid
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