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Slide 1

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(1997)…read more

Slide 2

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Previous research which have used a variety of
techniques on both animals and humans has
indicated that dysfunction in certain localised brain
areas may predispose individuals to violent
behaviour…read more

Slide 3

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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.
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…read more

Slide 4

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The method is a laboratory experiment using an independent
measures design.
The IV is whether the participant had committed murder or not.
The dependent variables were the results of the PET scans.
The study used PET scans to examine the brains of 41 people (39
males and 2 females) who were charged with murder and were
pleading Not Guilty for Reasons of Insanity
Each subject was matched with a normal subject on age and sex as a
All the NGRIs were referred to the imaging centre for legal reasons,
such as to obtain evidence for the defence. The reasons for the
referrals were: Schizophrenia (6 cases), Head injury or organic damage
(23), Drug abuse (3), Affective disorder (2), Epilepsy (2), Hyperactivity or
learning difficulties (3), Personality disorder (2)…read more

Slide 5

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All offenders were in custody and were kept medication
free for the two weeks before brain scanning. The control
group were also medication free.
All of the participants were injected with a glucose tracer,
They were then required to work at a continuous
performance task that was based around target
recognition for 32 minutes,
Then given a PET scan.
The NGRIs were compared with the controls on the level
of activity (glucose metabolism) 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…read more

Slide 6

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NGRIs were found to have less activity in their
prefrontal and parietal areas- links to loss of self
control, altered emotion, lower verbal ability
They had more activity in their occipital areas
No difference in their temporal areas.…read more

Slide 7

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Slide 8

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