- Raine et al 1997
- The aim of the study was to look at direct measures of both cortical and subcortical brain functioning using PET scans in a group of murderers who have pleaded not guilty by reason of insanity (NGRI).
- The expectation was that the murderers would show evidence of brain dysfunction in their prefrontal cortex as well as in other areas that are thought to be linked to violent behaviour.
- 1. Used PET scans to examine brains of 41 people. (39 male and 2 female
- 2. Compared them with the same number of controls
- Controls matched for age and sex. 6 of the murders pleaded guilty due to schizophrenia
- 3. All offenders were in custody and were kept medication free for the two weeks before brain scanning. The control group were also medication free.
- 4. All of the participants were injected with a glucose tracer, required to work at a continuous performance task that was based around target recognition for 32 minutes, and then given a PET scan.
- the NGRIs were compared with the controls on the level of activity in right and left hemispheres of the brain in 14 selected areas. The researchers looked at activity in six cortical areas and eight subcortical areas
- 5. n this study, compared to the controls, the NGRIs were found to have less activity in their prefrontal and parietal areas, more activity in their occipital areas, and no difference in their temporal areas.
- The results from the subcortical areas found less activity in the corpus callosum They also found an imbalance of activity between the two hemispheres in three other subcortical structures.
- In the amygdala and the hippocampus, compared to the controls, the NGRIs had less activity in the left side and more activity in the right side. Also, in the thalamus the NGRIs had more activity in the right side, though no difference in the left side.
- The main methodological strength of this study is the amount of control the researchers had over the procedure. For example they used a control group who were matched on variables such as age and sex and they were screened for their physical and mental health.
- It can also be argued that PET scans are useful because we no longer have to wait for a person to die before we can examine their brain. The scan allows for a wide range of non-intrusive studies.
- However the study does have methodological weaknesses. For example PET scans are still being developed and therefore the data should be treated with caution.
- It is also important to question the notion that all murderers are violent. NGRIs are not necessarily charged with murder because of a violent act. It is possible to murder someone with poison, which it could be argued is not violent. Dr Shipman might be an interesting example of murder without violence. This of course depends upon your definition of violence.
- The main criticism of this study refers to the issue ofreductionism. Studies like this one have been criticised for being biologically reductionist in that they attempt to explain complex behaviour as a consequence of brain functioning.
- By doing so this ignores the many other possible reasons why a person may act violently. Brain functioning is possibly just one factor why a person may act violently. Other factors that must be taken into account include a persons social background, their role models, psychological predispositions, learned responses and so on.
Similar Psychology resources: