Raine's study written out in full, for you to write flashcards/mindmaps or just to memorise for the potential of it coming up in paper 3 as the 10 mark question in crime.
The aim was to study brain activity in murderers using PET scans to find out whether there were
differences in areas thought to be involved in violent behaviours. It was a quasi experiment, the
IV was whether the P was a murderer or not, and the DV was measures of brain activity and
structure. It was a matched pairs design, each P (murderer) was paired with a member of the
control group (non-murderer), by age, sex and psychiatric condition (6 had schizophrenia). It
was an opportunity sample of 41 murders, 39 male and 2 female with a mean age of 34.3. They
had all been charged and convicted of murder/manslaughter, but all pleaded not guilty by
reason of insanity. They were referred to the Uni of California (brain imaging centre) for
confirmation of their diminished capacity. The control group were volunteers (also 41 Ps). No Ps
took any medication for at least 2 weeks prior to testing. P’s were brain scanned during a
continuous performance task (CPT), this was chosen as it increases brain activity in the areas
of interest in normal P’s. The P’s were allowed to practice the CPT before the test began. 30
seconds before being injected with a tracer, fluorodeoxyglucose, the P’s began their full CPT
session. This was to ensure that the novelty of the task didn’t appear as an ‘event’ on the brain
scan. The CPT session lasted for 32 minutes. After this, PET images of 10 horizontal ‘slices’
were taken at 10 mm intervals. Two techniques were used to identify brain regions: 1) cortical
peel technique (lateral brain areas - sides and surface) and 2) box technique (medial brain
areas - e.g. superior frontal gyrus). They found that murderers had less activity in the lateral,
medial and parietal prefrontal cortical areas compared to non-murderers. They also had
asymmetrical activity in areas of their limbic systems, including the amygdala (less activation on
the left, more on the right) and greater activation on the right temporal lobe, hippocampus and
thalamus. This study provides evidence for the areas of the brain that are associated with
aggressive behaviour (amygdala, hippocampus and the thalamus): the amygdala is responsible
for lack of fear and of expressing emotions. The prefrontal cortex is associated with
impulsiveness. All of these factors could lead to an increased risk of committing extremely
violent criminal acts.
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