Raine Et Al (1997) Flashcards
What is the aim of Raine et al. (1997) ?
To use brain scanning technology to identify brain impairments in people charged with murder who pleaded not guilty by reason of insanity (NGRI).
What is the sample of Raine (1997) ?
- 82 participants - 41 murderers and 41 non-murderers
- Only 2 women and 39 men in murderers group
- All from California USA
- Matched on age and sex
Describe the procedure of Raine (1997).
- Participants were told to be free from all medication in the 2 weeks up to their PET scan which was confirmed by urine tests.
- Control participants had a physical examination and a psychiatric interview and none of them were taking medication nor did they have a history of psychiatric illnesses - except for 6 diagnosed with schizophrenia who were matched on this.
- They were injected with a radioactive tracer to highlight brain metabolism on the scanner.
- Each completed a continuous performance task (CPT) after given a 10 minute practice period involving identifying targets on a screen and pressing a button during the 32 min period.
- This was to encourage uptake of the tracer in the areas that they wished to look at.
- The PET scan was conducted immediately after taking 10 images through the brain at 10mm intervals.
What are the findings of Raine (1997) ?
- Murderers had significantly lower glucose metabolism in cortical regions - lateral and medial prefrontal areas, left angular gyrus, left and right superior parietal areas.
- Murderers has higher levels in the occipital lobe - not previously linked to violence.
- Murderers had lower metabolism in sub cortical regions - corpus callosum, left amygdala, left medial temporal lobe, hippocampus.
- They had greater activity in the right amygdala, right medial temporal lobe, right thalamus.
What is the IV of Raine (1997) ?
Murderers or non-murderers - matched pairs design.
What is the DV of Raine (1997) ?
Glucose metabolism in specific brain areas.
What were the conclusions of Raine (1997) ?
- Murderers pleading NGRI have different brain activity from people who are not violent offenders.
- Dysfunctions of a single brain area can’t explain violent behaviour - not simple cause and effect manner.
- We should be very cautious interpreting findings because there are other brain areas known to be involved in violence that they were unable to scan, acknowledging that the study can’t give a complete explanation of the neurophysiology of violence.
Strengths of Raine (1997).
G - Large sample size of 82 ppts, anomalies with unusual brain structure or those not focused on the CPT should not skew the data too much, representative of wider target population.
R - The same standardised procedure, CPT was used for all ppts each having 32 mins, PET scan followed same well-established protocol, ensured ppts concentrated on the same thing ensuring all had similar types of brain activity, replication to check consistency.
A -
V - High control over extraneous variables, matched pairs design of age and sex, lab experiment, easy task that didn’t require a high IQ.
E - PETs are invasive because ppts are injected with radioactive tracer, medical procedure for controls that would not otherwise been taken, increased risks.
Weaknesses of Raine (1997).
G - NGRI’s are unusual offenders, killed someone but either don’t remember or too confused to stand trial, not representative of typical murderers, not easily applied to all criminal offences.
R -
A - Must be cautious with biological evidence as it at face value can suggest deficits in metabolism in particular structures cause aggression and can be treated through medication, however this is identified in the study.
V - The CPT was too artificial, signal detection is not reflective of violent or provocative behaviour they would have displayed during the crime, may have caused different reactions in the brain.
E - PETs are invasive because ppts are injected with radioactive tracer, medical procedure for controls that would not otherwise been taken, increased risks.
