QUASI EXPERIMENT with a 'matched pairs' design.
Independent variable: NGRI or not
Dependent variable: brain differences.
Participants: 41 (39 men 2 women) with a mean age of 34.3. All charged with murder or manslaughter and all pleaded not guilty for reason of insanity or incompetence to stand trial. The reasons for referral were that the murderers had some sort of mental impairment.
Control group: matching each murderer with a normal individual of the same age and sex. Apart from matching six schizophrenics with the original six schizophrenics, the other controls had no history of psychiatric illness (or in their relatives) and had no significant physical illness (none were taking medication.
1. Using the sample obtained by opportunity sampling, Partcipants were firstly asked to practice the Continuous Performance Task (CPT) - which was aimed to actuvate target areas of the brain so the investigators were acortical peel ble to see how different areas funtioned - before revieveing the Flurorodeoxyglucose (FDG) injection - this is a tracer which is taken up by active areas of the brain,making it possible to compare the brains of the NGRI participants and the control group-.
2. 30 seconds before he FDG tracer injection was carried out, the participants began the CPT so that the initial task novelty would not be FDG labelled.
3. 32 minutes after the FDG injection, PET (positron emission tomography) scans were done of each particpant. Ten horizontal slices (pictures) were done using the cortical peel and box techniques. They made sure to include precise details of scanning techniques so that the study was able to be replicated.
Reduced actvity (reduced glucose metabolism) in the brain of NGRI participants in areas previously lined to violence (the prefrontal cortex, the left angular gyrus, the corpus callosum and -in the left hemisphere- the amygdala, thalamus and hippocampus).
Increased activity in the Brain of NGRI participants in areas not previously linked to violence (the cerebellum and -in the right hemisphere- the amygdala, thalamus and hippocampus). This applied to some of the areas identified in the hypothesis as being linked to violece (the ones in the hemipheres).
No difference between NGRI and control groups in areas not previously linked to violence (caudate, putamen, midbrain and the globus pallidus).
Both groups performed similary on the CPT, therefore any observed brain differences were not related to task performance.
(other differences not controlled for) -part of 'F
Handedness: 6 murderers were left handed, therefore they had less amygdala asymmetry and higher medial prefrontal activity than right handed murderers.
Ethnicity: 14 participants were non-white however there was no significant difference in brain activity.
Head injury: 23 murderers had a history of head injury, however they did not differ from the others.
A lot of past research done on both animals and humans have identified the links between areas of the brain and agression. These findings are further supported by the findings of this study also. When grouped together, all research in this field provides preliminary evidence that murderers pleading NGRI have differing brain functioning than 'normal' individuals.
Neural processes underlying violence are complex and cannot be reduced to a single brain mechanism. Violent behaviour can most probably be best explained as the distruption of a network of interacting brain mechanismsrather than a single structure. This distruption wouldnot cause violent behaviour but predispose an individual to it.
Confounding variables: head injury and IQ (had not been ruled out as contributory factors)
The experimenters emphasise that it is important to recognise that the study does not show: 1. that violent behaviour is determind by biology alone, 2. that murderers pleading NGRI are not responsible for their actions, nor that PET can be used for diagnosis, 3. that brain dysfunction causes violence (brain dysfunction could be an effect), 4. that violence can be explained by the results(the results only relate to criminal behaviour!)
However, the findings do suggest a inkbetween brain dysfunction and a predisposition to violence in this particular group (NGRI murderers)
Evaluation: methodology and procedures.
Quasi-experiment - the independent variable was an already existing variable of the individual. Casual conclusions are not justified. as Raine et al. point out in their conclusions, the findings do not show that violent behaviour is determined by biology alone but that social and culturalfactors play important roles in the predisposition to violence - the limitation of this method is that no casual conclusions are able to be drawn. There is also a danger that people who read up on this study misinterperet the findings and assum criminal behaviour is predetermined and inescapable.
The research technique: PET scans - theseenable the brain in action to be examined. In this study meant that raine et al. were able to see how the braind og different individuals differed in the way they processed informtation.
The sample: the murderers- they were not typical of all violent individuals. the findings dont show that all violent people have brain dysfuntions or the other way around but can only draw conclusions about this type of violent offender (one with a mental impairment. Additionally, the crime done by all participants is muder (or manslaugter) however many violent crimes do not involve murder - ths theconclusions are resricted to a certain type of person.
Evaluation: alternative evidence.
Adrian Raine continued to to conduct research on the association between criminal behaviour and brain dysfuntion.
Yang and Raine (2009) carried out a meta-analysis of 43 imaging studies considering both antisocial and violent behaviour, concluding that there is significantly reduced prefrontal activity in these types of individuals (antisocial and/or violent).
The findings of this study are also supported by genetic studies indicating the existence of the 'criminal gene'. One candidae for this is the MAOA (monoamine oxidase A) gene which is linked to causing abnormally high levels of dopamine. A recent study by tiihonen et al. (2015) found an association between this gene and the increased likelihood of committing a violent crime by analysing the genes of 895 Finnish prisoners.
It should be rememebered that genes are predisposing factors! IE when James fallon analysed his own genes, he found he had the genetic and brain characteristics of a violent criminal, he was not one. He suggested that his positive experiences during childhood must have meant that his potentially criminal tendencies werenot triggered (which is a diathesis-stress explanation) -diathesis: a genetic predisposition only manifested if triggered by stressors-in this case it could have been a difficult childhood.
The main group in this study are those pleading guilty for reason of insanity or incompetence to stand trial - so they may not have been competent to provide valid consent.
The participants may not have known what to do so when it came to the continuous performance task they may find it difficult and could have an effect on their psychological well-being which is an example of psychological harm.
They could also have found the PET scan a distressing experince if they did not know what they were taking part in.
They may not have understod their right to withdraw at any time - especially as they were prisoners. They may have felt under obligation to take part and that they could not oppose.
The study has wider social implications - meaning it has consequences for the larger group of which the partcipants are members.
Is our understanding of criminal behaviour advanced by this research? if murderers are born rather than influenced to be this way then this may have consequences which my be disadvantageous for those with similar brain abnormalities. They even be imprisoned without trial or reference to their social circumstances - this research definitely has implications for other criminals.
Important desicions must be made about the way the research is reported and conducted.