This is the Classic Biological Study, so every student has to know it and the Examiner will expect you to be familiar with details. As well as general questions about the Aims, Procedure, Results & Conclusions (APRC), you could get fairly specific questions on how Raine matched his sample, carried out his brain scans or specific differences in brain structure he observed..

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RAINE ET AL. (1997)
THE CLASSIC STUDY: BRAIN ABNORMALITIES IN MURDERERS

This study was carried out by Adrian Raine on a group of American prisoners who were all charged with murder but were pleading Not Guilty by Reason of Insanity (NGRI). The precise reasons varied from schizophrenia to head injuries. As part of their defence, the prisoners received brain imaging scans and Raine took the opportunity to compare the prisoners’ scans with a group of Controls.

This study is significant for students in other ways:

• It shows how scientific research proceeds, because previous research on animals (eg on cats, by Mirsky & Siegel, 1994) suggested a link between brain structure and aggression, but it wasn’t known if this could be generalised to humans.
  
• It illustrates features of the Biological Approach, since it uses a brain imaging technique called Positron Emission Tomography (PET) to study brain structure.
• It illustrates the power and shortcomings of the natural (or quasi-) experimental method, because the participants’ criminal background was a naturally-occurring variable outside of Raine’s control.
• It shows the growing importance of neuroscience – the link between Cognitive and Biological psychology
  

POSITRON EMISSION TOMOGRAPHY (PET)

PET is a brain imaging technique that was still quite new in the 1990s. It involves injecting the participant with a glucose solution that dissolves in the blood. This glucose solution has been “tagged” with a radioactive tracer which will make its way to the brain. This takes about half an hour.

"Radioactive tracer" sounds pretty scary. Don't worry, it's harmless. Participants don't get radiation poisoning or develop super-powers.

Inside the brain, blood takes oxygen to regions that are active. A PET scan will show these regions as having a higher relative amount of the radioactive tracer. A computer can produce a scan of the brain from the radioactive signal, colouring in active regions as “hot” (yellow/red) and less active regions as “cold” (blue/green).

• Previous studies have suggested a link between certain regions of the brain and aggression. For example, the prefrontal cortex is supposed to restrain aggression, so Raine was interested to see if the NGRIs had less activity here; the thalamus was linked to aggression in cats, so Raine looked to see if there was more activity here.
  
• It’s important that all the participants are in a similar mental state during the scan. All participants are given a Continuous Performance Task (CPT): they wear earphones and press a button every time they hear a beeping tone. This involves concentration and should active the prefrontal cortex.
  

RAINE ET AL.'S STUDY
APRC

Aim

To find out if there is a difference in the structure of brain activity between people who have committed murder (NGRIs) and non-murderers. In particular, Raine looked at the role played by the prefrontal cortex, the corpus callosum, the amygdala, the medial temporal lobe (MTL)/hippocampus and the thalamus in predisposing people towards aggression. Raine wanted to see if the findings of studies linking brain structure to aggression in animals could be generalised to humans.

Yes, the MTL/hippocampus is the same brain structure studied by Schmolck et al. in the Cognitive Contemporary Study.

IV

Whether the participant is an offender pleading Not Guilty by Reason of Insanity (NGRI) to murder, or a non-murderer in the Control group.

Since the IV is naturally-varying and the Controls were matched on age and sex, this is a natural experiment with what looks like matched pairs design. However, Raine didn’t pair each participant’s results up with their “opposite number” in the other group, so really this is independent groups design.

DV

Relative glucose levels in the prefrontal cortex, the other lobes of the brain, the corpus callosum, the amygdala, the MTL/hippocampus and thalamus, as revealed by Positron Emission Tomography (PET).

Sample

41 offenders pleading NGRI to the crime of murder and 41 Controls. The NGRIs were 39 men and 2 women (mean age 34.3); 23 had a history of brain damage, 3 with a history of drug abuse, 6 suffered from schizophrenia, 2 with epilepsy and 7 with other emotional or learning disorders. The Controls were people of the same age and sex with no history of crime or mental illness, except 6 Controls who had schizophrenia.

The NGRIs should be considered an opportunity sample; Raine does not describe how the Control group was recruited so that may be considered to be an opportunity sample too.

Procedure

The participants were tested at the University of California. Each was injected with the glucose tracer and then performed the Continuous Performance Task (CPT) for 32 minutes. Then the PET scan was carried out.

Raine used other experimental controls:

• The participants were allowed to practice the CPT ten minutes before the glucose tracer was injected to make sure they were all equally familiar with it.
• Raine made sure none of the participants (NGRIs or Controls) was on medication; the NGRIs had been kept medication-free for 2 weeks before the PET scan.

Results

The PET scan was broken down into digital “slices” and “boxes”, enabling Raine to measure the relative amount of tracer present in the brain’s 4 cortical regions (the “lobes” on the outside of the brain) and the 4 sub-cortical regions (structures tucked away deeper inside the brain). Raine's illustration of the "slices" is shown below:

"Tomography" means "building up a 3-D image from slices" and that's how PET scanning works

As expected, the NGRIs showed less activity in the frontal lobe, especially the prefrontal cortex which is associated with rational thinking, self-restraint and memory.

There was also less activity in the parietal lobe, which is associated with abstract thinking (such as “morality” or “justice” but more activity in the occipital lobe (vision).

In the sub-cortical region, the NGRIs had less activity in the corpus callosum: the “bridge” of nerve fibres connecting the brain’s two hemispheres (associated with long-term planning).

There was also an imbalance of activity between the left and right hemispheres in the limbic system. There was less activity on the left and more on the right in the amygdala and MTL/hippocampus; more activity on the right side of the thalamus. These are areas of the brain associated with aggression in animals.

This table summarises some of the findings, showing the mean relative glucose metabolism observed by the PET in different regions. Scores that might be helpful in an Exam are in red:

Conclusions

Raine suggests how the brain abnormalities in the NGRIs might translate into violence or anti-social behaviour:

• Prefrontal deficits (deficits are lack of activity) might make someone more impulsive and emotional
• Deficits in the limbic system might make someone aggressive, as was observed in cats; the amygdala controls urges and desires, the thalamus processes information and the hippocampus processes memory (see the  study by Schmolck et al.). Deficits might make it hard for someone to learn from mistakes or understand their emotions.
  
• Deficits in the corpus callosum make it harder for the brain’s hemispheres to communicate, making it difficult to think through long term consequences and make decisions
• Areas like the parietal lobe, amygdala and hippocampus have a part to play in recognition; deficits here might make it harder for someone to judge social situations, leading them to overreact.

Raine concludes that findings from animal studies into aggression can be generalised to humans and there is a link between brain structure and aggression.

Raine is optimistic that these brain deficits can be prevented if they are identified early enough.

Early health intervention and prevention studies may provide the most effective way of reversing biological deficits that predispose to antisocial and aggressive behaviour in children and adults – Adrian Raine

A FEW WORDS OF CAUTION FROM ADRIAN RAINE

Raine and his colleagues devote a lot of space to evaluating their own study. They are cautious in their conclusions.

• On a positive note, they point out that this is the largest sample yet subjected to brain imaging for this purpose, it includes a Control group with good matching and it looks at different areas of the brain associated with aggression.
• On the other hand, they admit that the PET images were not particularly clear and there was a limit to how accurately they could be measured.
• The findings only apply to this group of murderers pleading NGRI, not to all violence.
• Raine insists that he is NOT claiming that violence is purely biological. He thinks social and situational factors, like culture and upbringing, play a part too.
• The study doesn’t show the causes of these brain deficits – whether the participants were born this way or acquired them later.
• Not all murders are violent acts and not all the NGRIs were accused of violent murders (for example, poisoning is a non-violent murder). It is not possible to link brain deficits with violence.
• Perhaps most importantly, Raine insists that his results do NOT show that the NGRIs had no freewill or that they “couldn’t help themselves” when they committed their crime. Brain structure can only give us a predisposition towards acting a certain way: the choice it still our own.

Biology is not destiny, and it's more than biology, and there's lots of factors that we're talking about there, and one factor like prefrontal dysfunction ... doesn't make you a criminal offender - Adrian Raine

EVALUATING RAINE ET AL. AO3
GRAVE

Generalisability

Raine et al. use a large sample (82), which was the largest at the time for this sort of study. Anomalies, such as participants with unusual brain structure or people who disrupted the test by not focusing on the CPT, should not skew the data too much. This makes the results representative of a wider population.

On the other hand, the NGRIs are unusual offenders. They are people who have killed someone, but either don’t remember doing it or are too confused to stand trial. These people are not representative of “typical” murderers, still less of typical violent individuals. As Raine points out, not all of the NGRIs killed their victims violently.

Reliability

PET is a reliable brain imaging technique that has been used (with growing success) since the 1970s. It produces objective and replicable results and it can be tested and re-tested to check its reliability.

The CPT also ensures that all the participants were concentrating on the same thing, which should ensure they all had similar types of brain activity. This is a standardised procedure that also adds to reliability.

However, Raine admits that there were still problems with the reliability of PET scanning in the 1990s. The results were sometimes unclear and had to be interpreted, which introduces subjectivity and low reliability.

Application

Raine is NOT claiming that PET scanning could identify murderers in advance. Nor is he claiming that PET scans could help decide whether or not someone is guilty of murder. DON’T MAKE THESE CLAIMS FOR THIS STUDY.

Raine does suggest that, if the damage that causes these brain deficits can be prevented, people might be prevented from becoming murderers; they will not develop a murderous predisposition. This involves early intervention with at-risk children in school, programmes to steer young people away from drugs and monitoring people who have received brain injury.

It also might be possible to treat people who suffer from these brain deficits. If the deficient parts of the brain can be stimulated (either through drug therapy or counselling), then they might be less likely to engage in impulsive, aggressive behaviour.

Validity

Bufkin & Luttrell (2005) carried out a meta-analysis, where they analysed the results of 17 studies that use brain imaging to study aggression in humans (Raine et al. is one of the studies they analysed). They found that all the studies point to similar conclusions: impulsivity is linked to deficits in the prefrontal cortex or the amygdala and such people have difficulty coping with negative emotions. This adds to the construct validity of Raine’s study, since it shows the results tie in with the findings of lots of other studies.

The CPT used by Raine could be criticised for being artificial and unconnected to violence or provocation. The participants were all doing an unusual task and in an unusual state of mind when the PET test was carried out. This lowers the ecological validity of the study.

As a natural experiment, this study cannot show cause-and-effect. For example, the NGRIs might have developed their brain deficits after the killing, because of the stress of the event, their arrest and imprisonment and their coming trial.

A similar idea is that there is another explanation for aggression: it is learned behaviour, as shown in the Bobo Doll studies by Bandura. If people learn aggressive behaviours, their brains might change because of it. This means that brain deficits aren't the cause of aggressive behaviour; they're the result.

The study only looks at brain activity and this could be a very reductionist view of human behaviour: an explanation from one narrow perspective that doesn’t take in “the big picture”. To be fair, Raine makes a point of explaining that personal, social and cultural influences might be at work as well as brain deficits. Another study that looks at genetic and environmental factors behind aggression is Brendgen et al. (2005).

Ethics

The NGRIs agreed to have the PET tests because it would help their court case, either by showing they were not fit to stand trial or acting as evidence that they weren’t in control of themselves when they committed the crime The Controls all gave their prior consent to be tested and for their imaging data to be used in the study. The University of California approved the study. If the NGRIs or the schizophrenic Controls were not competent to consent, then presumptive consent was given by their lawyer or carer.

PET imaging is an invasive procedure, because the participants have to be injected with a radioactive tracer. The NGRIs were having this procedure carried out anyway, for legals reasons, but for the Controls this was a medical procedure they would not otherwise have undergone. It's not a serious or dangerous procedure, but any unnecessary medical procedure increases the risk of research.

Furthermore, there are ethical concerns with the conclusions for a study like this. It seems to suggest that some people are driven to kill by their brain structure and that their violence is out of their control. It invites us to “screen” prospective job candidates, perhaps even potential partners, to check they don’t have “a murderer’s brain.” Raine and his colleagues make it clear they are NOT drawing these conclusions themselves, but once a study like this is known to the public its conclusions may be misinterpreted. This would go against the social responsibility of ethical research.

EXEMPLAR ESSAY
An 8-mark essay on the CLASSIC Study

Evaluate the classic study from biological psychology. (8 marks)

• A 8-mark “evaluate” question awards 4 marks for AO1 (Describe) and 4 marks for AO3 (Evaluate). Remember to include a conclusion in order to get the top band (7-8 marks).

Raine et al. carried out a very reliable experiment. The PET scan can be replicated and produces the same results every time. The CPT was also a standardised procedure and every participant performed the same task for 32 minutes.

However, PET scanning was still in its infancy in the 1990s and it's still a method that is open to interpretation. It's difficult to know exactly which parts of the brain are activating and what their functions are. The differences between the NGRIs and Controls were still quite tiny  (eg -0.04 in the prefrontal cortex). This counts against the study producing clear, consistent results.

The validity of the study is backed up by a meta-analysis by Bufkin & Luttrell, who found 16 other studies with similar findings about the link between prefontal cortex and limbic system deficits and aggression. We know the prefrontal cortex has a role in restraining aggression, so Raine is producing the results we would expect to find. This gives the study construct validity.

However, in some ways the study lacks validity. For one thing, the CPT was unrealistic and had no connection to violence or emotional arousal. It might have been more realistic if the participants watched a violent video or played a violent video game. Also, not all murders are violent: many require planning and self-control which are exactly the qualities Raine's NGRIs are supposed to lack.

In conclusion, Raine et al designed a good study into brain structure with offenders who had committed an unusual crime. Taine is cautious about drawing conclusions from the results, because the study does not explain why all murders happen or even how the NGRIs came to have these brain deficits.

• Notice that for a 8-mark answer you don’t have to include everything Raine et al. did. I haven’t mentioned the ethical issues or the problems with PET testing. But I have tried to make the two halves – Description and Evaluation – evenly balanced.