Raine et al 1997

Raine et al. 1997 Psychology

Raine et al. (1997)¹ sought to shed light on this claim by analysing a group of 41 murderers who had pleaded NGRI. Using a positron emission tomography (PET) scan, they investigated the brains of these murderers and found some interesting and revealing results.

Many areas of the brain are associated with specific functions, but truly identifying the regions and confidently saying they are responsible for said functions is not an easy task.

Many psychologists have acknowledged the localisation of function within the brain and have attempted to establish the areas responsible for specific behaviours and actions.

Psychologists have also argued that dysfunction in these areas results in violence and sometimes criminal behaviours in psychology.

Raine et al. (1997) sought to identify these potential areas of abnormalities in the brain. They hypothesised that violent offenders who plead NGRI would have dysfunction in the prefrontal cortex, angular gyrus, amygdala, hippocampus, thalamus, and corpus callosum.

Raine et al. 1997 Methodology.

Raine et al. (1997) carried out their experiment using a quasi-experimental design. The independent variable was whether the participant was a murderer who had pled NGRI or a normal person, and the dependent variable was the areas of brain dysfunction.

The participants consisted of 41 subjects who had been tried in California (US) - thirty-nine men and two women charged with murder or manslaughter.

They were referred to the University of California for imaging services due to their plea of insanity/incompetence. During this period, all of the participants were in custody. The referrals were based on diagnosed conditions like schizophrenia, brain injury, epilepsy and other disorders.

To ensure the subjects being tested were indeed showing abnormalities, each was matched with a normal subject of the same age. The controls were also tested with a PET scan localised to the same location.

The exception was the six participants with schizophrenia were matched with six people with schizophrenia who had not murdered anyone.

Raine et al. 1977: Procedure

Raine et al. (1997) used fluorodeoxyglucose (FDG), a tracer that gives off radiation when injected into the body. A PET scan can detect the radiation, producing an image of areas of high activity (usually indicated by red/yellow colours) and low activity (usually indicated by blue/green).

FDG was injected and taken up by the brain (a brain metabolic rate of 32 minutes), during which Raine et al. (1997) had the subjects complete a continuous performance task (CPT), to test the patterns of brain activation in subjects.

In the task, each participant wore earphones and pressed a button every time they heard a beep; this task involves concentration and should, in theory, activate the prefrontal cortex.

Brain Abnormalities in Murderers: Raine et al. (1977) Results

Results of Raine et al. (1997) indicated differences in brain activity in both the cortical and subcortical regions in murderers compared to controls.

Overall, there were no significant differences between the groups in their performance on the task.

Fig 2. PET scan example of a normal, healthy brain.

Raine et al. (1997) Summary

Overall, considering the above results, we can say that murderers have lower glucose metabolism in the following brain area:

• Bilateral prefrontal cortex

• Posterior parietal cortex

• Corpus callosum

They also show asymmetrical levels of activity in their left and right hemispheres in the following brain regions:

• Amygdala

• Thalamus

• Medial temporal gyrus

• Hippocampus

These results support the notion of there being a biological difference in murderers when they are compared to healthy people.

Areas of the limbic system specifically (e.g. the amygdala) aid in the control of emotion and modulation of aggression. Impairment in these areas could lead to inappropriate responses to threats.

Raine et al. (1997): Evaluation

Let's consider its strengths and weaknesses.

Raine et al. (1997): Strengths

Raine et al. (1997) established the largest sample size for an experiment of this type. They collected a sample of violent offenders, accounting for variabilities and ruling out issues such as ethnicity and head injuries whilst analysing behaviour during the entire process.

Their results provided an important base for future research.

Their results are quite reliable, considering the technique they used.

Using strict procedures, like matching the murderers with similar controls, means that the results found and associations made could be considered highly valid.

Raine et al. (1997): Weaknesses

Although the controls could consent to the experiment, the murderers were not fully able to consent. This is due to a potential inability to understand what the experiment entails, as well as how the results may impact their plea for NGRI.

Despite Raine et al. (1997) insistence that the results do not mean that these dysfunctions cause people to commit violent or murderous acts, they may still be misconstrued and interpreted as such.

The study can also promote a deterministic view of behaviour. It suggests that violent behaviours are due to biological dysfunction and ignores the idea of free will and personal responsibility.

The study does not provide much information about other violent offences, reducing generalizability and utility.