Raine et al (1997)

  • Created by: Mbegum
  • Created on: 29-12-18 16:35
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  • Raine et al (1997)
    • Methodology
      • Overall
        • Quasi-experiment
        • matched pairs design
        • IV = NGRI or not
        • DV = brain difference
      • experimental group
        • 39 M + 2F
          • mean age = 34.3
        • all charged w/ murder or manslaughter
          • pleaded not guilty by reasons of insanty
        • referred to uni of California for evidence of NGRI
          • referred on basis of mental impairment
            • e.g scz + head injury
        • medication free
          • checked via urine scan 2 weeks prior to brain scans
      • control group
        • each murder matched w/ normal indiv via age + sex
          • scz = matched w/ scz from mental hospital
        • medication free
    • Procedures
      • opportunity sampling
      • PET scans
        • study active brain
      • injected FDG tracer
        • tracer taken up by active areas of brain
          • therefore can compare betw/ NGRI / not
      • Continuous performance task
        • activates target areas of brain
          • therefore investigate how diff areas func
      • process
        • practise CPT before FDG
        • 30sec before FDG = start CPT
          • therefore initial task novelty = not FDG labelled
        • 32min after FDG injected = PET scan done
          • 10 horizontal slices via cortical peel + box technique
    • Findings
      • Brain differences
        • reduced activity in NGRI = areas prev linked to violence
          • prefrontal cortex
          • left angular gyrus
          • corpus coallosum
          • left hemis of amygdala + thalamus + hippocampus
        • increased activity in NGRI = areas not prev linked to vio
          • cerebullum
          • right hemis of amygdala + thalamus + hippocampus
        • no difference in NGRI + cotrol = in areas not prev linked to vio
          • caudate
          • putamen
          • globus pallidus
          • midbrain
      • Performance on CPT
        • both groups = similar performance on CPT
          • therefore any nrain diff = not related task related
      • uncontrolled differences
        • handedness
          • 6 NGRI = left handed
            • less amygdala assymetry VS right hand
        • ethnicity
          • 14 non-white NGRI
            • no s.f diff in brai activity
        • head injury
          • 23 NGRI = history of head injury
            • no diff
    • Conclusion
      • Overall
        • This research + past research
          • preliminary evidence for NGRI having diff brain func VS normal indiv
        • neural processes unferlying violence
          • complex + can't be reduced to single brain mech
        • vio behav explained via disruption in network of interacting brain mech
          • disruption = causes predisposition + not cause
      • Confounding Variables
        • carefully designed
          • large sample
            • matched controls
        • head injury + IQ not ruled out as confounding variables
      • warnings
        • results do not show
          • vio behav = determined by bio alone
            • social + psych + cultural factors play a role
          • murderers pleading NGRI = not responsible for actions
          • PET scan = not a way to diagnose a vio indiv
          • brain dysfunction doesn't cause vio
    • evaluation
      • methodology & procedures
        • quasi experiment
          • experiments = has IV + DV
            • quasi = IV already existing + not manipulated by researcher
              • causal conclusion not justified
        • Research Technique
          • PET scans
            • allow detailed study of different regions of brain whilst in action
              • Raine = investigate how diff indiv process different info
        • The sample
          • sample = only of murderers
            • not all vio indiv are murderers
              • cannot generalise findings to all vio indiv
      • alternative evidence
        • Yang et al
          • meta-analysis of 43 imaging studies
            • found s.f reduced prefrontal cortex activity in antisocial + vio indiv
        • tiihonen et al
          • 895 finnish prisoners
            • MAOA gene = causes high levels of dopamine
              • link betw/ MAOA gene + increased chance of committing vio crime
        • James Fallon
          • had genetic characteric of vio crim
            • wasn't ciminal = healthy upbringing
              • genes not triggerred via diathesis-stress theory
      • ethical issues & socila implications
        • valid consent
          • sample = NGRI
            • mayn't be mentally competent to provide valid consent
        • socially sensitive research
          • Untitled
        • psychological harm
          • may not have understood what to do
            • may have found CPT hard = lower self-esteem
              • PET scan = distressing experience
        • right to withdraw
          • prisoners = therefore may not have known about right to withdraw and felt pressured to continue

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