Two Key Studies using fMRI & PET Scans: Fisher et al. (2003) & Raine et al. (1997) (DP IB Psychology)
Revision Note
Written by: Claire Neeson
Reviewed by: Lucy Vinson
Key Study 1: Fisher et al. (2005)
Aim: To investigate the brain systems involved in early-stage intense romantic love.
Participants: 10 females and 7 males from New York State University (self-selecting sample), aged from 18-26 years old (mean age 20). All participants reported being ‘in love’ (a range of 1-17 months; mean = 7 months).
Procedure: Participants were placed in an fMRI scanner and shown a photograph of their loved one followed by a distraction task and then a ‘neutral’ photograph of an acquaintance with whom they had a non-emotional relationship.
Results: The researchers found that when the participants viewed the photograph of their loved one specific areas of the brain were active: the right ventral tegmental areas and the right caudate nucleus. Both of these areas are strongly associated with dopamine activation (a neurotransmitter which induces a feeling of reward and motivation in people).
Conclusion: The results suggest that people in the early, intense stages of romantic love access the areas of the brain most associated with motivation and reward, giving rise to the idea that people become ‘addicted to love’. Dopaminergic reward pathways may contribute to the ‘general arousal’ component of romantic love, making it a biological process rather than a cognitive one.
Evaluation of Fisher et al. (2005)
Strengths
The use of a standardised procedure means that the study is replicable, which increases its reliability
The use of fMRI means that the study was able to support to the idea that human beings may have evolved a brain system which ensures that they become addicted to love which increases the study’s validity.
Limitations
The small sample size of 17 participants means that the results are not very meaningful and may not be robust in terms of statistical analysis.
The idea that romantic love can be measured via fMRI is overly reductionist: there may be a range of other factors involved, such as compatible personalities, shared ideals, cultural influences.
Key Study 2: Raine et al. (1997)
Aim: To investigate whether there are any differences in the brains of impulsive murderers compared to non-murderers.
Participants: 41 murderers (39 males and 2 females) who had been tried in California for either murder or manslaughter. They had all pleaded NGRI – not guilty by reason of insanity (6 had schizophrenia; 23 had head injuries or organic brain damage; 3 had a history of psychoactive drug abuse; 2 had depression; 2 had epilepsy). They had a mean age of 34.3.
The study used a matched pairs design consisting of a control group of non-murderers (matched on age and gender, around the same age, with 6 schizophrenic individuals in the group).
Procedure: Each participant was injected with a radioactive tracer. 30 minutes after the injection, the participant was placed in a PET scanner. The participants were asked to complete a series of simple cognitive tasks e.g. recognising a 0 while the PET scan took place. 10 pictures were recorded which provided details in relation to differences in glucose metabolism in specific areas of the brain.
Results: The impulsive murderer group showed less activity in the prefrontal cortex (PFC), an area of the brain which has been linked to impulse-control and the ability to plan ahead. The murderer group also showed asymmetrical activity in the amygdala (more activity on the right side than the left) which means they were more likely to experience a lack of emotional control, a lack of fear and the inability to learn from past mistakes.
Conclusion: Brain dysfunction (seen via PET scan as a lack of activity in the PFC and asymmetry of the amygdala) may mean that someone is more prone to violent outbursts.
Evaluation of Raine et al. (1997)
Strengths
The use of a matched pairs design means that individual differences could to some extent be controlled for
This use of a purposive sample of NGRI murderers increases the validity of the study as the participants had all experienced a lack of control which led to violent behaviour thus they may all share similar features of brain function
Limitations
The results of this study may lead to a deterministic bias against offenders guilty of impulsive murder i.e. that they have no autonomy or free will and are at the mercy of their biological functions
This is an example of a snapshot design: it cannot tell us anything about behaviour across time
Examiner Tip
You can use Fisher et al. (2005) in a question on NEUROTRANSMITTERS AND THEIR EFFECT ON BEHAVIOUR.
Worked Example
Discuss techniques used to study the brain in relation to behaviour. [22]
What follows are two paragraphs evaluating Raine et al. (1997). Note the way in which the response expands on and develops the points put forward, the use of terminology and the focus on the question:
It might be inferred from Raine’s findings that NGRI murderers do not use their PFC to interpret and respond to non-emotional stimuli, reacting instead in an emotional manner which could indicate unusual amygdala activity. If the NGRI murderers had been using their amygdala rather than their PFC to interpret behaviour then it is possible that this might have resulted in low impulse control and thus, violent murder. The external validity of such a finding is, however, debatable; it is not a straightforward path from a result observed in a PET scan to behaviour enacted in real settings. There is no real evidence to show conclusively that the NGRI murderers’ crimes came from the same biological place; there could be a huge range of other influences that produced the behaviour e.g. alcohol abuse, situational pressure, upbringing in a violent home etc. In this way, a PET scan is limited as it can only tell one part of a complex story; the role of the PFC may in fact have had little to do with the NGRI’s crimes, but it is interesting nonetheless to note that all of the NGRI sample shared this same lack of activity in the PFC.
One of the main strengths of Raine (1997) is that it used a large sample in terms of PET scan research, the largest up to that point in time. The effect size reported by Raine was also quite robust, being 0.55, showing that there may well indeed be a biological correlate (low PFC activity) that is linked to impulsive, violent behaviour (impulsive murder). Without the use of a PET scan, it would have been impossible for Raine to ascertain such results and to reach a solid conclusion. The findings of this study were really the first in the field of criminal behaviour research to link PFC function with criminality. Raine’s findings might be used in clinical and forensic settings to inform rehabilitation programmes and to go some way towards preventing crimes from taking place, although this is a more problematic prospect as it requires knowledge of each criminal’s brain activity which can only be achieved via expensive scanning methods.
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