Practical Investigation- Raine Et Al (1997) Flashcards
(14 cards)
1
Q
What is the aim of Raine et als 1997 study?
A
To investigate patterns of brain activity in the pre-frontal cortex of murderers who pleaded not guilty by reason of insanity compared to a matched sample of non-murders using PET scan (Positron Emission Tomography).
2
Q
What was hypothesised about Raines study?
A
That individuals who showed serious violence would have dysfunction in specific areas of the brain, but not others, those areas being the PFC, angular gyrus, amygdala, hippocampus, thalamus and corpus callosum.
3
Q
What was the method/procedure or Raines study?
A
- An experimental group.
- 41 PPS guilty of murder or manslaughter but had pleaded ‘not guilty by reasons of insanity’.
- Experimental PPS been referred to University of California to obtain evidence that they could not understand the jury process (incompetent to stand trial). If already guilty, had diminished capacity.
- Experimental group: 6 schizophrenia, 23 organic brain damage/ head injury, 3 substance abusers, 2 affective disorder, 2 epilepsy, 3 hyperactivity/ learning disorder, 2 passive aggressive/ paranoid personality disorder.
- 39 men, 2 women, average age was 34.
- These PPS were matched with a control group (plus 6 schizophrenia). People in the control group were removed if they had a history of seizures, head trauma or substance abuse.
- PPS did not take any medication for 2 weeks prior to testing.
- Given PET scan whilst carrying out a continuous performance visual task for 32 minutes, designed to measure activity via glucose metabolic rates, in the frontal lobes.
- Task consisted of a sequence of blurred numbers to focus on & was chosen because it was shown to increase glucose metabolic rates in the frontal lobes, so would help to highlight areas of interest.
- PPS given practice test 10 minutes beforehand.
4
Q
What were the results of Raines study?
A
- Significant differences were found between experimental group & control group in activity in the pre-frontal cortex, corpus callosum and parts of the limbic system. Murderers showed lower levels of activity in these areas.
- These areas are associated with self-control, emotional responses and inhibition of violent behaviour.
- Murdered also had lower activity in the parietal cortex, linked to verbal ability and suggesting lower educational attainment in the murdered- possible contribution to their criminal behaviour.
- Prefrontal lobe= murderers had lower glucose metabolism relative to controls and the parietal lobe; no differences in the temporal lobe and higher glucose metabolism in the occipital lobe; lower glucose metabolism in the corpus callosum; lower activity in the left amygdala and greater activity in the right amygdala than the controls; reduced activity in the left medial temporal lobes, including the hippocampus and increased activity in the tide side of the medial temporal lobe and hippocampus and greater activity in the right of the thalamus.
5
Q
What was the conclusion of Raines study?
A
- Areas of the brain with lower activity in the murderers (ie PFC linked to lack of fear, lowered self control, increased aggression and impulsive behaviours and problems with controlling and expressing emotions.
- Problems with these parts of the brain could indicate a significantly increased risk of committing extreme violence.
- The hippocampus, amygdala and thalamus have all been related to learning and it has been suggested that abnormal activity here could result in people being unable to modify their own behaviour by learning from the consequences of their actions.
- Limbic deficits show the amygdala is associated with aggressive behaviour in both human and animals. The amygdala, hippocampus and PFC govern the expression of emotion and the thalamus relays information.
6
Q
Describe the generalisability of Raines study.
Strength
A
The behaviour being studied in the sample was quite representative and the largest sample of its kind to be studied this way. Men mainly commit violent crime.
7
Q
Describe the reliability of Raines study.
Strengths
A
- Well controlled, experimental and control group were well matched for sex, age and mental health and none of the PPS took any medication 2 weeks prior to the study (in case it affected the results and performance of the continuous performance task.
- Age, gender, schizophrenia, handedness, ethnicity and history of head injury were all ruled out as confounding variables.
- Murderers with head injury had reduced glucose metabolism in the corpus callosum, it could be the head injury damaged the corpus callosum.
- All PPS could do the task so there for no differences in attention.
- PET scans are reliable and objective. Results are quantitative and replicable (having more people undergo the same procedure in the PET scanner or having another scan).
8
Q
Describe the reliability of Raines study.
Weaknesses
A
- Didn’t measure IQ of PPS but may not have accounted for differences.
- Possibility of individual differences in regard to the images generated by the PET scan as these images are based on the location of certain brain ‘landmarks’ that differ within each individual.
- Another Raine study in 2000 showed PPS with anti-social personality disorder have a smaller PFC than normal PPS, when looking at the volume of the brain. This is consistent with the findings of 1997 studies high found murderers hqd lower levels of activity than the control in the PFC.
9
Q
Describe the applicability of Raines study.
Strengths
A
- Study was of criminal behaviour and of those who commit extreme acts of violence; potentially violent offenders could be detected using diagnostic brain scans so future offending behaviour could be predicted & possible intervention strategies used; useful for potential mitigation in trials.
10
Q
Describe the applicability of Raines study?
Weakness
A
- However, Raine maintains that the casual connection brain abnormalities & violence could not be established with any degree of certainty.
11
Q
Describe the validity of Raines study.
Strengths
A
- ## PET scans are very precise, objective measures of brain activity but difficult to interpret accurately.
12
Q
Describe the validity of Raines study.
Weaknesses
A
- Difficult to interpret PET scans accurately.
- Cause and effect difficult to verify (may be a relationship between lower brain activity in the PFC & likelihood of extreme violence, but it might not be necessarily the cause of this violence.
- Does not take into account social, psychological and cultural factors for criminal behaviour which might be just as, or more, important as biological factors.
- Only looked into very specific group of violent offenders, those pleading guilty by reason of insanity, not to all types or violent behaviour or non-violent criminals. The control group did not include non-violent criminals so it is not possible to link the brain differences with violence.
- Images produced by PET scans at the time are not particularly clear and the measuring in 1997 had limitations.
- Study does not give causes of the brain dysfunctions, such as genes or the environment. It describes the differences in brain structure but does not explain them: nature or nurture?
13
Q
Describe the ethicality of Raines study.
Strengths
A
- Consent was obtained & no distress was caused (experimental group have already been found guilty so cannot be caused distress by the thought that they might commit acts of extreme violence- they already had).
- The study was approved by an ethics committee at the University of California.
14
Q
Describe the ethicality of Raines study.
Weakness
A
- PPS might have felt under some stress to take part as they looked for evidence for mitigation of their crimes; if the PPS were mentally ill they may not have the capacity to give fully informed consent. Similarly, some of the PPS suffered from schizophrenia, substance abuse, brain injury and personality disorders, hindering their potential to give informed consent.
