Raine et al (1997)

• Methodology- describe the participants:

  41 murderers (39 men, 2 women). Mean age 34.3 years. All pleaded not guilty by NGRI (reasons of insanity). Referred to Uni of California to prove their diminished capacity.
• Procedures- which type of sampling was used?

  Opportunity sampling.
• Methodology- describe the experimental design & type:


  Matched pairs design- matched each murderer with 'normal' person of same sex & age from control group. 6 scz murderers matched with 6 from mental hospital. Quasi-experiment.
• Methodology- what was the IV & DV?

  IV- NGRI or not DV- brain differences
• Procedures

  PET scans used. Radioactive glucose (FDG) injected into bloodstream. Brain uses glucose for energy- more active parts use more glucose. Leaves faint radioactive trace in parts of brain most active-can be detected by PET scanner. Participants given chance to practice CPT. FDG injected after 30 seconds. After 32 mins, PET scan done. 10 horizontal slices of brain recorded using cortical peel & box techniques. Study has precise details of scanning techniques so study can be replicated.
• What is CPT?

  Continuous performance task.
• Findings:

  No difference in caudate, putamen, midbrain & globus pallidus. Increased activity in murderers (NGRI) in cerebellum, right hemisphere amygdala, thalamus & hippocampus. Reduced activity in NGRI murderers in left hemisphere amygdala, thalamus & hippocampus, prefrontal cortex, corpus callosum & left angular gyrus. Both groups performed similarly on CPT.
• Evaluate methodology & procedures:

  Chance to practice CPT, PET scans show brain activity, can see precise brain abnormalities in valid way. Only 2 women in sample- is it good representation? All pleading NGRI- won't represent all murderers. Not all criminals murder, so conclusions restricted. Quasi-experiment, so findings aren't determined by biology alone. No causal conclusions can be drawn.
• Social implications:

  Could improve rehabilitation for offenders to help get them back in society. Criminals may get away with crime, research could be used to make automatic judgement, people may label themselves as criminal-could lead to self-fulfilling prophecy. Could be misused to punish/limit people before committing crime.
• Evaluate ethics:

  Given consent, however NGRI, so may not have been in right mental state to consent. They may not have understood that they had a right to withdraw. May not have fully understood tasks & found them difficult-may have lowered self-esteem (psychological harm). May have found PET scan distressing experience.
• Which differences weren't controlled for (findings)?


  Handedness: 6 left-handed murderers (had less amygdala asymmetry & higher medial prefrontal activity than right-handed murderers). Ethnicity: 14 murderers non-white (no significant difference in brain activity compared to white murders). 23 murderers had head injury history, but didn't differ much from other murderers, with no history of brain injury.
• Conclusions:


  Links between brain areas & aggression. Neural processes underlying violence are complex & can't be reduced to a single brain mechanism. Violent behaviour best explained by disruption of network of interacting brain mechanisms rather than any single structure. Disruption won't cause violent behaviour, but would predispose individual to violent behaviour. Confounding variables: head injury & IQ.
• Warnings (conclusions):


  Results don't demonstrate that violent behaviour is determined by biology alone-social, psychological, cultural & situational factors play important roles in predisposition to violence. Murderers pleading NGRI still responsible for actions & PET scans not means of diagnosing violent people. Doesn't show brain dysfunctions causes violence (may be an effect). Doesn't show violence can be explained by results-they only relate to criminal behaviour.
• Yang & Raine (2009):


  Alternative evidence. Meta-analysis of 43 imaging studies that considered antisocial & violent behaviour. Found significantly reduced prefrontal activity in antisocial &/or violent people.