Classic study: Raine et al Flashcards
Aim
Use brain scanning technology to identify brain inpairments from criminals charged with murdered who pleaded not guilty by reason of insanity
Method:
What was the sample size
41 murderes matched with 41 non-murderes
Method:
IV and DV
IV - Whether the participant was a murderer or a non-murderer
DV - glucose metabolism in specific brain areas
Method:
How were the participants matched to the control group?
Age, sex and ethnicity
Method:
What brain scanning technique was used
PET scan
Procedure:
How many males and females were in the experimental group
39 males
2 females
Procedure:
WHat was the procedure of the study
participants injected with glucose tracer to light up brain activity
then had to performed a continous performance task for 32 minutes after the injection
Pocedure:
What was the purpose of having the participants perfome the continous performance task
Encourage uptake of radioactive tracer in areas of the brain the researchers wished to investigate
Findings corticol regions:
what cortical regions did murderers have lower activity in compared to the control group
lateral and medial prefrontal areas
left angular gyrus
Findings cortical regions:
What cortical regions did murderers have higher activity in compared to the control group
occipital lobe (area not previously linked to violance)
Findings subcortical regions:
What subcortical regions did murderes have lower glucose activity in compared to the control group
left amygdala
corpus callosum
hippocampus
Findings subcortical regions:
What subcortical regions did murderes have higher glucose activity in compared to the control group
right amygdala
right medial temporal lobe
right thalamus
What was the conclusion
Hypothesis was supported, murderes pleading NGRI had different brain activity.
Murderers had impared functioning in areas previously associated with violent offending
Strenth of control of the study:
What is a strength of the control of the study
The study had a high degree of controls.
Strenth of control of the study:
GIve an example in the study where there was a high degree of controls
Standarised procedures were used to control confoundings variables, for example…
- same continous performance task was used on all participants for the same length of time
Strenth of control of the study:
What did this mean for the study
It had high internal validity as confounding variables were controlled for
Competing arguement against control
What is a competing arguement for the controls of the study
The matching of participants was not done thorough enough
Competing arguement against control
Give example of a variable that wasn’t matched
Raine acknowledged 23 murderers had a history of head injury.
Competing arguement against control
What did the participants with head injury mean for the results
Affected the results, the activity difference of corpus callosum between 2 groups may have been explained.
Weakness of PET scan:
What is a weakness of using the PET scan
It may have given misleading results
Weakness of PET scan:
Evidence that it may have given misleading results
Technique scanned the brain in 10nm slices in a line fron the corner of the eye to middle of ear, this line is known to vary significantly from individuals
Weakness of PET scan:
What does this limitation mean
Hard to locate precisely different brain areas under study so internal validity is reduces
Strength of generalisability
What is a strength of the generalisability of the study
The sample size was large.
Strength of generalisability
Why is the sample size being large a strength?
Anomalies such as unusual brain structure or not paying attention during the CPT wouldn’t skew data too much.
Strength of generalisability
What did this mean for the results
The larger sample size means the results became more generalisable.
