Evaluation of the Raine study

The main methodological strength of this study is the amount of control the researchers had over the procedure.   For example they used a control group who were matched on variables such as age and sex and they were screened for their physical and mental health.

It can also be argued that PET scans are useful because we no longer have to wait for a person to die before we can examine their brain.   The scan allows for a wide range of non-intrusive studies.

However the study does have methodological weaknesses.   For example PET scans are still being developed and therefore the data should be treated with caution.

The task used by the participants before the scan is a general activity task and has no bearing on violent acts or even the decision to be violent.   Therefore the validity of the task could be questioned.

The major methodological weakness is related to the design of the study.   It has already been noted that the design was a type of natural experiment, which means that the researchers could not randomly allocate participants to either of the two conditions.  Therefore we have to be careful in making cause and effect statements.  It is possible that any differences in brain activity between the two groups could have been caused by other factors.   We can only say that the study shows a correlation and not a causal relationship.   For example, it could be that the differences between the two groups might have been a result of the crime and its consequences rather than a cause of it.

There is also supporting evidence for Raine’s study.   For example another study by Raine et al. (2000) found that people with anti-social personality disorder had a smaller pre-frontal cortex than normal controls, which supports the findings of this study because it suggests that brain differences may cause anti-social behaviour.  Similarly, in a 20 year longitudinal study Raine measured the way that 3 year old children learned fear.  He found that some showed little or no fear response despite repeated exposure to an unpleasant noise.  These children when looked at 20 years later were significantly more likely to have a criminal record.  This suggests that the emotional connection between experience and fear was missing leading to those affected being more likely to take stupid risks.

However other evidence suggests that we have to be careful accepting the findings of Raine’s 1997 study.  In a large scale study in Denmark, Raine examined the birth records of people and found 4000 who had suffered complications and therefore possibly brain damage.  He also looked at the records of those who had been rejected by their mothers in the first year of life.  He found that neither factor alone was enough to predict criminal behaviour but for those who suffered both traumas they had more than double the risk of becoming criminals at aged 18.  This suggests that it is nature plus nurture that is responsible for criminal behaviour.

Raine thinks that the nature of the criminal’s brain should be taken into account in sentencing decisions.  He has acted as an expert witness on behalf of someone with a dysfunctional prefrontal cortex which led to a reduction in sentence from death to life in prison.  If we know that murder may be caused by faults in peoples’ biological make-up, then it means that we can work on ways to treat violent offenders by altering their biology.  There have been some people who have suggested treating criminals by trying to change or alter their brain chemistry.