RAINE et al – 1997 ‘Brain abnormalities in murderers indicated by PET’ RAINE et al (1997) AIM PROCEDURE Murderers – Average age 34.3 There ‘Brain abnormalities in To investigate patterns of brain Experimental group of 41 participants were 39 men and 2 women murderers indicated by activity in murderers compared to charged with murder/manslaughter who PET’ a matched sample of non- had pleaded ‘not guilty by reasons of murderers using PET scanning insanity’ but had been convicted (referred to as ‘murderers’)Murderers -23 had a history of brain damage, 6 Controls – Average age 31.7 The Independent variable is whether a Following a practice task participantsschizophrenia, 3 substance abuse, 2 mood A control group (normal participant is a murderer or not were injected with a radioactive glucosedisorder, 2 epilepsy, 3 learning participants) was matched for sex The Dependent variable is the measures tracerdisability/hyperactivity, 2 paranoid personality and age and who were similar in of brain activity and brain structuredisorder other ways e.g. 6 had found using PET scans schizophrenia. No participants were on medication.
They then did a ‘continuous performance task’ PET scans were performed RESULTS 3 differences:(a visual task that increases brain activity in the immediately after and used to Significant differences were found 1) Murderers had lower glucosefrontal lobes of normal participants) for 32 indicate the level of activity in between murderers and controls metabolism (i.e. less activity) in someminutes different brain areas pre-frontal areas of the brain.2) Murderers had less activity in corpus 3) Murderers had different levels CONCLUSION All of these could lead to an increasedcallosum (structure that joins the two halves of of activity in the amygdala The areas identified as having abnormal risk of committing acts of extremethe brain). activity are associated with LACK OF violence. The study suggests that FEAR, LOWER SELF-CONTROL, violence has a biological cause INCREASED AGGRESSION, HOWEVER Raine DID NOT conclude IMPULSIVE BEHAVIOUR AND that there were only biological causes PROBLEMS CONTROLLING AND for violence, just that there might be a EXPRESSING EMOTIONS PRE-DISPOSITION to violence in some people, depending on environmental triggers