Raine et al (1997)

• Aim

  Use brain scanning technology (PET) to identify brain impairments in people charged with murder who had pleaded not guilty by reason of insanity (NGRI). The researchers hypothesised that brain scans would show dysfunctions in areas linked in previous research to violence - the pre frontal cortex, angular gyrus, amygdala, hippocampus, thalamus and corpus callosum.
• Method

  Two groups - 41 murderers (39 men & 2 women) and 41 non-murderers

  IV - murderer or non murderer

  DV - glucose metabolism/ brain activity in specific areas (PET scans)

  Matched pair design and lab exp

  6 schizophrenia, 23 head injury etc. mean age 34.3

  All NGRIs referred to imaging centre for legal reasons

  All murderers in custody and medication free for 2 weeks before brain scanning - controls also med free
• Procedure

  Each P had a PET scan then all Ps injected with a glucose tracer and made to work at a continuous performance task based around target recognition for 32 mins. Task was to encourage uptake of the radioactive tracer in areas of brain that researchers wanted to investigate. Another PET scan straight after which took 10 images of brain
• Findings

  cortical regions - murderers had significantly lower glucose metabolism (or activity) than controls in lateral and medial prefrontal areas, left angular gyrus and left & right superior parietal areas

  murderers showed higher metabolism in occipital lobe - not previously linked to violence
• Findings 2

  subcortical regions - murderers had lower glucose metabolism in corpus callosum, left amygdala and left medial temporal lobe (includes hippocampus)

  NGRIs had more activity in right amygdala, right medial temporal lobe and right thalamus
• Conclusions

  Hypothesis supported showed that NGRIs had diff brain activity to controls. They had impaired functioning in areas previously associated with violence. Cannot see dysfunctions of brain as causality - more of correlation and create a predisposition to violence that's only expressed when social, environmental and psychological conditions are 'right'.
• Raine is cautious

  Should be cautious in interpreting findings.

  Other areas of brain unable to scan which were also linked to violence. Does not hold NGRIs responsible - free will v biological determination.

  Doesn't talk about causes of brain diffs (schizophrenia v epilepsy)

  Study cannot give complete explanation + can't be generalised to diff types of crime or diff NGRIs
• Strength 1

  Experimental control - high degree of control -

  standardised procedure like same CPT used for all for 32 mins

  all Ps matched on 3 potentially confounding variables (sex, age, ethnicity)

  PET scans all followed same procedure so all had same experience

  high internal validity as potential confounding variables controlled

  CA matching was not thorough - 23 w head injury may affect results
• Strength 2

  Application to gaining more insight on violence from a biological perspective which could be used to identify a potentially aggressive person and therefore 'treat him' through medication. CA: however Raine et al argue that meds would not be justified as this only offers partial explanation
• Weakness 1

  Reductionism - tries to explain a complex behaviour as a consequence of brain functioning - simplifying complex behaviour to basic components while ignoring other factors such as social background, role models, learned responses etc.

  Murder may not mean violence - Dr Shipman

  Ethically - socially sensitive research, takes away blame
• Weakness 2

  PET scanning technique may not be accurate - 10mm slices taken from imaginary line from outer corner of eye to middle of ear. This line known to differ significantly between individuals which makes it hard to locate brain areas - reduces internal validity and places doubt on studies accuracy