Classic Study: Raine et al (1997) Flashcards
What was the aim of Raine’s study?
- To show that the brains of murderers who pleaded not guilty by reason of insanity were different from the brains of non-murderers
- To investigate if this abnormality makes them more aggressive and so reduces accountability
Who were used in the sample?
- 41 murderers pleading NGRI
- 41 non-murderers
What participant design was used?
Matched pairs on sex and age, 6 non-murderers having schizophrenia to match the 6 murderers with schizophrenia.
What type of method was used?
Lab
Briefly describe the procedure of this classic study.
- 10 mins before being given a FDG injection for the PET scan subjects were given practice trials on the continuous performance task
- 30 secs before the injection, the real CPT task started and were monitored for 32 mins in the PET scan
- The CPT involved spotting targets on a screen and pressing a button to indicate the target had been recognised
- Their brains were scanned 10 times at 10 minute intervals to pick up differences in glucose metabolism in the cerebral cortex and sub-cortical layers
What was the IV and DV?
IV = Whether the ppts were murderers or non-murderers DV = Level of brain activity, measured by level of glucose, in certain areas of the brain
What were the results of Raine’s study?
- Parietal lobes of murderers had lower activity in both hemispheres than controls with a difference of 0.05 in the left and 0.04 in the right
- Frontal lobs of murderers had lower activity in both hemispheres than controls with a difference of 0.03 for both
- Amygdala of murderers had lower activity in left (0.94) compared to 0.97 of non-murderers and greater activity in right (0.88) compared to 0.83 of non-murders
Describe the conclusion based on the parietal lobes.
The parietal lobes are responsible for speech and so if there is low activity in this region someone wouldn’t be able to articulate their feelings such as anger and so it gets differed to aggressive acts
Describe the conclusion based on the frontal lobes.
The frontal lobes are responsible for personality and self-control and so damage to the frontal lobes can result in impulsivity, lack of self control and the inability to modify behaviour which in turn can facilitate aggressive acts
Describe the conclusion based on the amygdala.
The amygdala plays a role in the recognition of affective and social significant stimuli and so abnormalities could be relevant to a theory of violence based on the findings of reduced autonomic arousal (fight or flight) and lack of fear in offenders
Describe the overall conclusion of this experiment.
Violent behaviour is controlled by areas of the brain and that abnormalities to these areas can affect behaviour, even though we can’t be certain that their violent behaviour was caused by these abnormalities.
Evaluate the generalisablity using a low point.
P - Low
E - Narrow sample of 41 murderers pleading NGRI
E - This is not a large sample and can’t be applied to non-violent offenders pleading NGRI
Evaluate the reliability using 2 high points.
P - High
E - Standardised procedure and controlled conditions due to using a PET scan and a 32 min CPT
E - Can be replicated easily
P - High inter-rater
E - PET scans are objective as they produce images
E - These can then be analysed by more than one researcher
Are there any applications?
P - Yes
E - Findings suggest that reduced brain activity in certain areas of the brain may act as a predisposition for violence
E - Violent criminals may therefore be less accountable for their actions which may have importance when their sentence is decided
Evaluate validity using 2 high points.
P - High
E - Matching the control group with murderers on mental illnesses, sex and age
E - Reduces ppt variables and so comparisons are more meaningful
P - High
E - Ppts stopped taking medication for 2 weeks prior
E - Nothing would have affect their brain activity
