classic: raine et al -brain abnormalities in murderers Flashcards
aims
raine 1997 wanted to investigate if there were brain differences between violent offenders and non- offenders.
This was a matched pairs design. the experimental group contained 41 participants who had all been charged with murder or manslaughter and had pleaded NGRI. The group consisted of 39 males and 2 females, 6 had schizophrenia.
The control group was also used in which people were matched in age, sex and mental disorder,
39 males 2 females, 6 schizophrenia
all participants were medication/drug free for 2 weeks prior to study.
procedure -The participants were tested at the University of California. Each was injected with the glucose tracer and then performed the Continuous Performance Task (CPT) for 32 minutes. Then the PET scan was carried out.
Raine used other experimental controls:
The participants were allowed to practice the CPT ten minutes before the glucose tracer was injected to make sure they were all equally familiar with it.
results- there was no difference in performance on the tasks between the two groups.
- the murderers had lower glucose metabolism in some prefrontal areas, corpus callosum and different levels of activity in the amygdala.
conclusions
murderers pleading NGRI have different brain activity compared with others who are non-violent offenders. This suggests that violence has a biological cause eg prefrontal deficits can mean loss of self control. however researchers did not conclude that there were only bio causes for violence, just that there might be a predisposition to it in some people depending upon environmental triggers.
generalisability
:( the sample only represents a small number of severely violent offenders as those pleading NGRI are not representative and therefore it can not be considered a representative exp of violence.
CA- largest sample size for pet scanning and large enough for useful comparison with the control group and generalisation to those pleading NGRI
reliability
:) pet scanning is an objective technique and the results can be interpreted by more than one researcher. it is a scientific method and is likely to give reliable findings.
:) environment also consistent for both groups
validity
:) high degree of control eg participants were matched across the experimental and control groups on three potentially confounding variables.
:( scanning using pet are conducted in contrived areas which may mean participants were responding to the environment and could effect the measures of brain function in an unusual setting.
CA- use of pet provided for scientific measure to ensure accuracy of results found.
ethics
:) all agreed to take part to support legal defence - informed consent
:( are the findings socially sensitive. research suggests that crime is bio determined and implies that offenders are not in control.
