Zusammenfassung der Ressource
Raine et al (1997)
- ABOUT
- AIM
- To find out if there is a difference in the structure of brain activity between
people who have committed murder (NGRIs) and non-murderers
- IV
- Whether the participant is an offender pleading Not Guilty by Reason
of Insanity (NGRI) to murder, or a non-murderer in the Control group
- DV
- Relative glucose levels in the prefrontal cortex and other lobes of the brain
- SAMPLE
- 41 offenders pleading NGRI to the crime of murder and 41 Controls
- PROCEDURE
- The participants were tested at the
University of California.
- Each was injected with the glucose tracer and then
performed the Continuous Performance Task (CPT) for 32
minutes.
- The participants were allowed to practice the CPT ten minutes before the glucose tracer was injected
to make sure they were all equally familiar with it.
- Then the PET scan was carried out.
- RESULTS
- As expected, the NGRIs showed less activity in the frontal lobe, especially the
prefrontal cortex which is associated with rational thinking, self-restraint and
memory.
- There was also less activity in the parietal lobe, which is
associated with abstract thinking (such as “morality” or
“justice” but more activity in the occipital lobe (vision).
- In the sub-cortical region, the NGRIs had less activity in the corpus
callosum: the “bridge” of nerve fibres connecting the brain’s two
hemispheres (associated with long-term planning).
- CONCLUSION
- Raine suggests how the brain abnormalities in the
NGRIs might translate into violence or anti-social
behaviour:
- • Prefrontal deficits (deficits
are lack of activity) might make
someone more impulsive and
emotional
- Deficits in the corpus callosum make it harder for the
brain’s hemispheres to communicate, making it difficult
to think through long term consequences and make
decisions
- Raine concludes that findings from animal studies
into aggression can be generalised to humans and
there is a link between brain structure and
aggression.
- EVALUATION
- GENERALISABILITY
- Raine et al. use a large sample (82), which was the largest
at the time for this sort of study.
- RELIABILITY
- PET is a reliable brain imaging technique that has been
used (with growing success) since the 1970s.
- APPLICATION
- If the damage that causes these brain deficits can be prevented,
people might be prevented from becoming murderers; they will not
develop a murderous predisposition
- VALIDITY
- There is contract validity because the results tie in with the findings of lots of other
studies. Such as, Bufkin & Luttrell
- ETHICS
- PET imaging is an invasive procedure, because the participants
have to be injected with a radioactive tracer. The NGRIs were
having this procedure carried out anyway, for legal reasons, but
for the Controls this was a medical procedure they would not
otherwise have undergon