Classic Study - Raine

• Aim of Raine's study

  To investigate patterns of brain activity in murderers compared to a matched sample of non-murderers using PET scanning
• Procedure of Raine's Study - Sample

  • Experimental group of 41 participants charged with murder/manslaughter who had pleaded ‘not guilty by reasons of insanity’ but had been convicted
  • Murderers – Average age 34.3 There were 39 men and 2 women -All there for legal reasons - opportunity sampling
  • Murderers -23 had a history of brain damage, 6 schizophrenia etc
  • Controls – Average age 31.7 A control group (normal participants) was matched for sex and age and who were similar in other ways e.g. 6 had schizophrenia. No participants were on medication (they were taken off medication for 2 weeks).
• Procedure of Raine's Study - Variables

  The Independent variable is whether a participant is a murderer or not

  The Dependent variable is the measures of brain activity and brain structure found using PET scans

  natural experiment/ quasi experiment (doesn’t have control over IV)
• Procedure of Raine's Study

  • Following a practice task participants were injected with a radioactive glucose tracer
  • They then did a ‘continuous performance task’ (a visual task that increases brain activity in the frontal lobes of normal participants) for 32 minutes
  • PET scans were performed immediately after and used to indicate the level of activity in different brain areas (Cortical Areas - e.g. prefrontal cortex , Subcortical - Amygdala. 
• Findings of Raines' Study

  Significant differences were found between murderers and controls and the 3 main differences were:

  1. Murderers had lower glucose metabolism (i.e. less activity) in some pre-frontal areas of the brain.

  2) Murderers had less activity in corpus callosum (structure that joins the two halves of the brain).

  3) Murderers had different levels of activity in the amygdala. (Less activity in the left side and more activity in the right)

  = inappropriate emotional expression
• Conclusion of Raines's Study

  • Raine concluded that murderers pleading NGRI have different brain activity from people who are not violent offenders. The murderers had impaired functioning in areas of the brain previously identified as involved with violent behaviour. 
  • All of these could lead to an increased risk of committing acts of extreme violence.  The study suggests that violence has a biological cause HOWEVER Raine DID NOT conclude that there were only biological causes for violence, just that there might be a PRE-DISPOSITION to violence in some people, depending on environmental triggers