Raine et al Flashcards
Aim
To show that the brains of murderers who pleaded NGRI were different from the brains of non - murderers
Procedure
(subjects)
41 murderers pleading NGRI and 41 matched controls.
Main ppts were 39 men and 2 women, either charged with murder or manslaughter
All had been referred to the University of California
What did the groups consist of?
People with a history of brain damaged or schizophrenics
None of the controls had committed murder
Experimental controls
All offenders were in custody and were kept medication free for two weeks
Tests were also conducted to make sure that being left - handed and right - handed had no impact on behaviour
Procedure
- 10 minutes before FDG injection subjects were given practice trials on CPT so they knew what to expect.
- 30 seconds before the injection, the real task was started so the initial task would not be recorded
- Once they had been injected, they were monitored for 32 minutes and were scanned in PET scans
- Brains were scanned 10 times
Results
There was evidence of a significant difference in brain metabolism of glucose in a number of areas
Evidence that murderers pleading NGRI have different brain functions compared to normal controls
Results
There was evidence of a significant difference in brain metabolism of glucose in a number of areas
Evidence that murderers pleading NGRI have different brain functions compared to normal controls
Summary of results
- Frontal lobes had reduced glucose metabolism relative to controls in both lateral and medial pre frontal cortical areas
- Limibc system (amygdala) abnormalities reduced in left and greater in right
Conclusion
Confirm that the brains of murderers pleading NGRI are different to non - murderers.
Data also confirms deficits in the pre frontal cortex may be linked to violent behaviour
Regarding the amygdala, the limbic system has been repeatedly associated with aggressive behaviour, as such abnormalities in the amygdala could be relevant to fearlessness theory of violence based on findings of reduced autonamic arousal in offenders
Generalisability (Low)
- Low in generalisability as the study took place in the university of California, using ppts who had pled NGRI in America.
- It doesn’t represent over murderers who pled NGRI in other countries so lacks external validity as it limits how useful brain activity is.
Generalisability (High)
- The study had the largest sample that had been used in PET scan study, 41 murderers who pled NGRI and 41 in a control group
- It’s hard to find this select group of individuals as not many people have committed murder and pled NGRI so this is quite a large sample
Reliability (High)
- The experiment group of 41 ppts were matched with the control group of 41 ppts based on factors such as age and sex
- This is good because results will be kept consistent as all NGRI ppts were matched on specific variables
Application
- Raine et al found that there was reduced functioning in the left amygdala and higher in the right amygdala
- Could lead to the development of treatments that could balance amygdala function to prevent individuals from committing violent crimes
Validity (Low)
- The findings only describe the brain differences but does not explain them
- The brain scans were carried out after the violent acts had been committed, therefore, we cannot say for certain that the brain differences were there before the murders took place
Validity (High)
- There was a matched control group 41 non - murderers were matched as part of a control group based on variables
- This means that Raine was likely to be accurately measuring the effect of brain functioning on behaviour on those who had pled NGRI
