Classic study - Raine et al (1997) Flashcards
What were the 2 aims ?
- To use brain scanning technology to identify brain impairments with people charged with murder who had pleaded not guilty by reason of insanity
- Hypothesised brain scans would show dysfunctions in areas linked in previous research to violence
How many participants were there ?
82 = 41 offenders pleading NGRI to crime of murder & 41 controls
How many men & women were in the NGRI group ?
39 men & 2 women
How many NGRIs had different backgrounds ?
23 - history of brain damage
3 - history of drug abuse
6 - schizophrenia
2 - epilepsy
7 - other emotional/learning disorders
Did controls have any history of crime or mental illness ?
No apart from 6 with schizophrenia
What similarities were between NGRIs and controls ?
Same age & sex
How were participants recruited ?
Opportunity sampling - not stated explicitly for control
What was the IV ?
Whether the participant is an offender pleading NGRI or a control
What was the DV ?
Relative glucose levels in the PFC & other lobes in the brain using PET scans
What experimental design is used ?
Independent group design
What was the practice test ?
Visual targeting task - CPT
How long was the practice test ?
10 minutes
What happened after the practice test ?
Injected with fluorodeoxyglucose trace was injected
What did participants complete after the glucose tracer ?
CPT for 32 minutes
What was recorded from the CPT ?
Target recognition
What happened after the 32 minute period of FDG uptake ?
PET scan of the head
What were the results in the right amygdala ?
NGRIs = 0.88
controls = 0.83
What were the results in the amygdala ?
NGRIs had reduced activity in left amygdala & greater activity in right amygdala than controls
What were the results in the PFC ?
NGRIs = 1.14
Controls = 1.18
What were the results in the corpus callosum ?
NGRIs = 0.56
Controls = 0.68
What did Raine conclude for prefrontal deficits ?
Makes someone more impulsive & emotional
What did Raine conclude for deficits in the limbic system ?
May make someones aggressive & hard to learn from mistakes or understand emotions = amygdala controls urges & desires
What did Raine conclude around deficits in the corpus callosum ?
Make it harder for brain’s hemispheres to communicate = harder to think through long term consequences & make decisions
How does the study have high internal validity ?
- Control over 3 potentially confounding variables
- Participants matched on sex, age & ethnicity
- Results paired more accurately
How is the study objective ?
- PET scans measure glucose metabolism in brain
- Brain scans = highly scientific by predicting computerised images of brain activity identified by colour
- Red = high , blue = low
How is the study scientifically credible ?
- Use of scientific measures alongside standardised procedures
- Findings can be falsified
How is the study high in generalisability ?
- Large sample = 82 participants
- Anomalies wouldn’t overly skew data
- Representative of wider target population
How is the study not generalisable in terms of NGRIs ?
- NGRIs unusual offenders
- Murderers who are too confused to understand trial or don’t remember killing
- Not representative of ‘typical’ murderers
- Findings can’t be applied to all criminal offences
How is the study not generalisable in terms of women ?
- 2 women in experimental & control groups
- Limits gen to female offenders pleading NGRI
- Not truly representative of wider target population
What are the applications of the study ?
Deficits in glucose metabolism in particular brain structures cause aggression = treated through medication
Why may the study not be applicable ?
Study identifies brain structures as partial explanation for behaviour = not full case
How is the study reliable in terms of PET scans ?
- Used since 1970s
- Produces objective & replicable results
- Can be tested & retested
How is the study reliable in terms of CPT ?
- Standardised procedures
- Same CPT fo 32m
- PET scans followed = well established protocol
- All participants concentrated on the same thing
- Similar types of brain activity
- Replicated to check for consistency
How is the study low in task validity ?
- CPT artificial
- Signal detection task
- Unrelated to violence or provocation
How is the study low in internal validity ?
- Cant show cause & effect
- Uncertain when murders developed brain deficits
- Did brain deficits develop after killing due to stress of events or did brain deficits cause aggression ?
How is the study reductionist ?
- Only looks at brain activity
- Simplistic view of criminal behaviour
- Social & cultural influences not taken into account
What is an ethical concern in terms of PET scans ?
- Invasive procedure for controls
- Participants injected with radioactive tracer
- Unnecessary medical procedure increases risk of research
What is an ethical concern in terms of the study ?
- Suggest people driven to kill by brain structure & violence is out of control
- Raine made clear not drawing conclusions themselves
- Once released to public = opened up to scrutiny
- Go against social responsibility of ethical research
