Raine (Topic 1 what makes a criminal?) Flashcards
What Raine et al studied
Brain abnormalities in murderers indicated by positron emission tomography
Background and Aim
Investigated brains of murderers who pleaded not guilty for reasons of insanity (NGRI) using positron emission tomography (PET) scans to see whether they have brain abnormalities.
If significant differences could be found between glucose metabolism patterns in brains of NGRI’s compared to non-murderers, may indicate murderers pleading NGRI are more prone to violence than non-murderers.
Until this study no previous brain imaging had been conducted in this area.
Raine carried out pilot study on 22 NGRI offenders compared to 22 ‘normals’ which showed support for idea of prefrontal brain dysfunction in NGRI’s.
PET scans
(positron emission tomography)
Show us which areas of brain MOST active through orange and red colours, and which are LEAST active through blue and green colours.
Two hypotheses tested
1- Violent individuals pleading NGRI have relatively localised brain dysfunction in prefrontal cortex, angular gyrus, amygdala, hippocampus, thalamus and corpus callosum (brain areas associated with violence)
2- These individuals show no dysfunction in other brain areas (i.e caudate, putamen, globus pallidus, midbrain and cerebellum) which are associated with psychiatric conditions, but NOT violence.
Method
Quasi experiment
IV= NGRI murderer or a ‘normal’, non-murderer not manipulated.
DV= whether the ps showed evidence of brain dysfunction in aforementioned areas of brain.
Experimental design
Matched pairs
Matched on age, gender and diagnosis of schizophrenia in 6 members of each group
Sample (experimental group)
39 men
2 women
(androcentric)
mean age 34.3 years old.
All had been charged with either murder or manslaughter, referred to University of California, Irvine (UCI) imaging centre to find if they were NGRI, if they were competent to understand the judicial process, or if there was any evidence of diminished mental capacity (may affect sentencing)
Sample in depth
6 had schizophrenia
23 had head injuries or organic brain damage
3 had history of psychoactive drug abuse
2 had affective disorders
2 had epilepsy
3 had history of hyperactivity and learning disability
2 had personality disorders
7 of above cases had particularly unusual circumstances relating to the murder.
Pre-experiment
Offenders were in custody for 2 weeks, kept medication free before brain scanning; none of controls were taking medication either.
Procedure
Firstly ps were given practice trials on continuous performance task (CPT) to activate parts of their brain. In the task targets need to be searched for and button pressed when found, concentration task activates pre-frontal cortex.
They were then given Fluorodeoxyglucose (FDG) injection which traces glucose metabolism in brain.
PET scans show where in brain glucose is being used, indicates activity in areas of brain.
30s later the real CPT task was given to ps.
32 mins later ps were transferred to adjacent PET scanner room where brain was scanned 10 times and 10mm intervals to measure activity in different regions of brain.
RESULTS
Murderers with head injury history showed NO SIGNIFICANT DIFFERENCE compared to non-head injured murderers APART from functioning of their corpus callosum (may have contributed to reduction in murderer’s brain activity.
NO SIGNIFICANT DIFFERENCES were found for performance on CPT.
NGRI murderers had REDUCED activity in prefrontal cortex, left angular gyrus and corpus callosum- all linked to VIOLENCE.
REDUCED activity on LEFT side and GREATER activity on RIGHT side of amygdala, thalamus and hippocampus.
NO DIFFERENCES in areas associated with mental illness but not with violence such as midbrain and cerebellum.
CONCLUSIONS
NGRI murderers have SIGNIFICANT DIFFERENCES in metabolism of glucose in number of brain areas compared to non-murderers.
REDUCED ACTIVITY in prefrontal, parietal and callosal regions of brain, and asymmetries of activity in amygdala, thalamus and medial temporal lobe, may be some of predispositions towards violence.
REDUCED ACTIVITY in prefrontal areas may explain impulsive behaviour, loss of self control, immaturity, altered emotionality and inability to modify behaviour. These factors seem to predispose an individual to aggressive acts due to normal constraints on behaviour being REDUCED.
Violent behaviour therefore cannot be reduced to a single brain mechanism and there are several processes involved.
If there are numerous deficits in these processes, likelihood of violence INCREASES.
CONCLUSIONS cont
However caution must be taken in making further conclusions, results do NOT show violent behaviour is biologically determined, must consider social and situational factors as well as learned behaviours.
Be careful not to attribute cause of murder as being due to mental disorder.
We CANNOt conclude NGRI pleading murderers are NOT responsible for their actions, or that PET scans can be used as way of diagnosing violent individuals.
Brain dysfunction does NOT cause violence; may be an effect of violence.
CANNOT conclude ALL violent offenders have brain dysfunctions and violence CANNOT be explained by results.
However can conclude results relate to criminal behaviour of murderers who then plead NGRI.
Usefulness
Provides evidence there are number of risk factors that may predispose child to criminal behaviour.
Findings useful in development of crime prevention strategies e.g biosocial intervention programmes can be implemented even before child born including health & nutrition programmes for pregnant women.
Free will / determinism
Raine concluded these brain dysfunctions are risk factors associated with criminal behaviour, but violence is not biologically determined, free will does play a part.
There are individuals who do have brain dysfunctions in brain areas associated w violence but they are not violent due to free will.
Reductionism / holism
Biological psychologists would argue for reductionist debate and that there is supporting evidence from this study.
NGRI criminals have different brains in areas associated with violence.
More holistic approach may be more appropriate as violent criminal behaviour may be learnt from experience, caused by faulty cognitions or due to social or developmental difficulties.
In reality psychological factors triggering biological predisposition is most likely explanation for ‘what makes a criminal’.
