Raine et al (1997)

Aim of the study
To examine the brain functioning of murderers who had NGRI using PET scans
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Hypothesis
Murderers will show evidence of brain dysfunction in their pre-frontal cortex in other regions of the brain linked to violent behaviour
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What type of experiment was used? What type of experimental design was used?
Quasi experiment & a Matched Pairs Design
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What was the I.V and D.V?
I.V.whether the participant was a murderer who had plead NGRI or a non-murderer & D.V.whether the participants showed evidence of brain dysfunction
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What mental disorders did the participants have & how many of each?
History of Head Injury or Brain Damage = 23, History of Hyperactivity and Learning Disability = 3, History of Psychotic Drug Abuse = 3, Affective Disorder = 2, Personality = 2, Epilepsy = 2, Schizophrenia = 6
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Describe the experimental group - MURDERERS
41 murderers (39 men/2 women) with a mean age of 34.3. They were referred to University of California to gain evidence to help there case. All murderers had some form of mental disorder.
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Describe the experimental group - NON-MURDERERS
This group were matched to murderers group based on sex & age. The 6 NGRI's with schizophrenia were matched with 6 schizophrenics with no history of murder.
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What type of sample was used? What type of experimental setting was used?
Opportunity sample & it was done in a controlled lab setting
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Describe the procedures of Raine's study
1. All pps were injected with radioactive glucose (FDG) after starting a CPT task which lasted 32 minutes. 2. After, they were examined & 10 pictures were taken using a PET scan. 3. The murderers & control group were compared in 14 areas of the brain
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Describe the findings of in terms of: Reduced activity
Reduced activity was found in areas with reduced glucose in some areas of the brain (those linked to violence). E.g. reduced activity in left Frontal & Parietal lobe, Amygdala, Thalamus, Hypthalamus
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Describe the difference in findings of the left hemisphere compared to the right
There was more reduced activity on the left side of the brain (areas linked to emotional expression & violence) than the right. No difference was found in structures linked to mental health & both groups had similar CPT performance
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What did Raine conclude?
A link was found between areas of the brain & aggression thus meaning there is evidence that murderers who plead NGRI have different brain functioning to 'normal' people. Neural processes are complex & does not cause violence but is a predisposition
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What 3 things do the results NOT show?
1. Violent behaviour is determined by biology alone: there's social/culture factors. 2. Murderers who plead NGRI aren't responsible for their actions or that PET scans should be used for diagnosis. 3. A causal relationship
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Evaluate the methodology - QUASI EXPERIMENT
Quasi experiment is hard to find a causal relationship due to lack of control of extraneous variables/participant variables; crime may have altered brain = low internal validity.But, quasi is the most realistic way of researching human behaviour
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Evaluate the methodology - MATCHED PAIRS DESIGN
Matched pairs design allows for the control of participant variables. But, it isn't possible to find a suitable match for all pps & differences may have been a result of NGRI violent disposition = low internal valdity
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Evaluate the methodology - PARTICIPANTS
The sample group were only murderers & so cannot be compared to all violent offenders. Also, sample was gender bias (more male) = low population validity
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Evaluate the methodology - USE OF SCANS
PET scans are scientific & objective = high internal validity. But, PET are less accurate than MRI scans & are quite new so may be error in interpretation across researchers = low internal reliability
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Evaluate findings/conclusion - SUPPORT RESEARCH
Yang & Raine conducted a meta analysis looking at antisocial and violent behaviour and found reduced activity in prefrontal cortex = increases external reliability
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Card 2

Front

Hypothesis

Back

Murderers will show evidence of brain dysfunction in their pre-frontal cortex in other regions of the brain linked to violent behaviour

Card 3

Front

What type of experiment was used? What type of experimental design was used?

Back

Preview of the front of card 3

Card 4

Front

What was the I.V and D.V?

Back

Preview of the front of card 4

Card 5

Front

What mental disorders did the participants have & how many of each?

Back

Preview of the front of card 5
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