Raine et al - classic study

Question 1

aim

Answer 1

• to share that NGRI murderers have different brains in comparison to non-murderers
• Raine hypothesised that seriously violent individuals would have relatively localised brain dysfunction in areas like the PFC, thalamus and amygdala

Question 2

sample

Answer 2

• experimental group: 41 ppts (39 men, 2 women) with a mean age of 34.9 years. all had a history of brain damage and schizophrenia, as well as their issues. all offenders were kept medication free for two weeks and urine samples confirmed they were medication free at the time of the PET scans.
• control group: 41 ppts (39 men, 2 women) with a mean age of 31.7 years.
• groups were matched in great detail, e.g. 6 schizophrenic controls matched with schizophrenic murderers.

Question 3

procedure

Answer 3

• 10 minutes before being given the FDG injection, subjects were given practice trials on the continuous performance task (CPT) so they knew what to expect. 30 seconds before injection, the real task was started so that the initial task novelty wouldn’t be recorded. once injected, subjects were monitored for 32 minutes and then underwent PET scans. their heads were held still in head holders.
• their brains were scanned for 10 minutes at 10mm intervals to pick up differences in glucose metabolism in both the cerebral cortex and sub-cortical layers.

Question 4

results

Answer 4

• there was evidence of a significant difference in brain metabolism of glucose in a number of areas. this gives preliminary evidence that NGRI murderers have different brain functions in comparison to normal controls.
• data: NGRI’s had different glucose metabolism in PFC then controls (media prefrontal lobes = 1.25 in controls and 1.20 in murderers for left hemisphere). murderers have asymmetrical amygdala activity, higher on right side (murderer = 0.94 in the right and 0.88 in the left hemisphere).

Question 5

conclusion

Answer 5

• it was concluded that the brains of murderers pleading NGRI are different to those of non-murderers. data also confirmed that deficits in the PFC may be lined to violent behaviour. (PFC is linked to decision making and if it’s not regulated we can become impulsive).
• violent behaviour is controlled my areas of the brain, even if we can’t be sure that the behaviour is actually caused by these abnormalities.

Question 6

strengths

Answer 6

• sample: high generalisability. this study has the largest sample used for a PET scan study (41 ppts in each group). therefore, results are more representative of brain activity - when using PET scans - in the wider population (both murderers and non-murderers).
• procedure: high reliability due to a standardised procedure. ppts were ministered for 32 minutes after being injected with FDG. therefore, this study can be more easily repeated to check for consistency in brain activity for murderers in comparison to non-murderers.
• results: high validity. glucose metabolism levels based off PET scans are an objective/quantitative measure of brain activity. therefore, results will be more accurate as they are free from bias.

Question 7

weaknesses

Answer 7

• sample: low generalisability. ethnocentric sample, all NGRI’s were tried in the state of California. therefore, results may not be representative of differences in brain activity cross-culturally.
• procedure: low ethics. subjects in the experimental group went medication free for two weeks. this may have had a negative impact on the well being of ppts, therefore ethical guidelines are not being adhered to.
• results: low validity. findings only describe brain differences and do not explain them as the brain scans were carried out after the violent act was committed. therefore, a cause and effect cannot be established as we can’t say for certain that the brain abnormalities were there before the act was committed.

Question 8

application

Answer 8

high application. suggest that institutions like prison and rehabilitation centres may not be of any use if violent actions are due to biology. pre-screening can be done and early interventions can be carried out if the screening suggests someone is developing violent tendencies, e.e. anger management class. therefore, we can give people a better quality of life and better society as well.