Classic Evidence: Raine, Buchsbaum & LaCasse (1997)

Methodology

Quasi Experiment - the researcher has not manipulated the IV directly & pps are not randomly allocated to each other

Matched Pairs Design - pairs of pps are matched in terms of key variable such as age and IQ. One member of each pair is allocated to one of the conditions under test and the second is allocated the other condition

IV - NGRI or not

DV - Brain Differences

Sample Size/pps: 41 murderers (39 men & 2 women) had an average age of 34.3 yrs

Mental Disorder & No. of pps:
Schizophrenia - 6
History of Head Injury/Organic Brain Damage - 23
History of Psychoactive Drug Abuse - 3
Affective Disorder - 2
Epilepsy - 2
History of Hyperactivity & Learning Disorder - 3
Personality Disorder - 2

Urine scan checked id pps were medication free 2 weeks prior to the brain scan

Control Group

Formed by matching each murderer with a normal individual of the same sex and age

The 6 schizophrenics were matched with 6 other schizophrenics from a mental hospital

None were tsking medication

Procedures

Sample was obtained using opportunity sampling

A PET Scan was used to study the active brain

All pps were given an injection of a tracer called Fluorodeoxyglucose (FDG) -> Tracer is taken up by the brain's active areas and therefore made it possible to compare the brains of NGRI & control group

All pps were asked to do a continuous performance task (CPT) -> task was aimed to activate the target areas of the brain so functions can be seen

1) pps were given a chance to practice the CPT before receiving the FDG injection
2) Thirty seconds before the FDG injection pps started the CPT so that the initial task would not be FDG labelled
3) 32 minutes after the FDG injection a PET Scan was done of each pps. 10 horizontal slices of their brain were recorded using:

  • Cortical Peel Technique - lateral regions measured
  • Box Techniques - medial & subcortical regions measured

Findings

NGRI:
Reduced Activity: Prefrontal Cortex, Parietal Lobe, Corpus Callosum, Amygdala (L), Hippocampus (L), Thalamus (L)
Increased Activity: Cerebellum, Occipital Lobe, Amygdala (R), Thalamus (R), Hippocampus (R)
No Difference: Caudate, Putamen, Globus Pallidus, Midbrain, Cingulate

Performance on CPT

No difference between murderers & controls in performance on CPT

Other Differences not Controlled For

Handedness - 6 murderers were left handed, little difference found between L&R handed people apart from Left handed showed high prefrontal activity & less abnormal amygdala amygdala asymmetry

Ethnicity - 14 murderers were non-white but no significant difference in brain activity was found

Head Injury - 23 murderers had a history of head injury but no difference was found compared to no history of head injury

Conclusions

  • Past research has identified links between areas of the brain and aggression
  • The findings provide preliminary evidence that murderers pleading NGRI have different brain function to normal individuals
  • But neural processes underlying violence are complex and can't be reduced to a single brain mechanism
  • Violent behaviour can best be explained by the disruption of a network of interacting brain mechanisms rather than any single structure
  • A disruption would not cause violent behaviour but would predispose an individual to violent beahviour

Confounding Variable

  • Study was designed involving a large sample and matched controls
  • However, Raine et al acknowledged that head injury and IQ have not been ruled out as contributory factors

Warning

Results:

  • Violent behaviour is determined by biology alone -> social, cultural, psychological & situational play a factor
  • Do not show brain dysfunction causes violence
  • Murderers pleading NGRI are not responsible for actions

Links between areas of the brain & aggression

Limbic System (Prefrontal Cortex, amygdala, hippocampus & Thalamus): Emotion - abnormal emotional response, Learning, Memory & Attention (abnormalities in functioning may results in reduced sensitivity to conditioning) - failure of violent offenders to learn from experience

Prefrontal Cortex: Deficit linked to impulsivity, loss of control, immaturity and inability to modify behaviour (associated with increased aggressive behaviour) - aggressive behaviour

Amygdala: aggressive behaviours in animals & humans. Destruction of amygdala in animals = lack of fear - fearlessness associated with violent activity

Hippocampus: modulates aggression in cats & with prefrontal cortex can inhibit aggressive behaviours - lack of inhibition of aggression

Angular Gyrus: damage to the left (deficits in verbal & arithmetic) - low verbal IQ, Poor school performance of violent offenders

Corpus Callosum: dysfunction related to a predisposition to violence & poor transfer of information between hemispheres - reduced processing of linguistic information

Right Hemisphere: dominance of right hemisphere (less regulation by left hemisphere) inability to process negative emotions & inappropriate emotional expression - lack of control over expressing violence

Evaluation: Methodology & Procedures

Quasi Experiment

Is an IV & DV

The IV was an existing condition of the individual not something manipulated by the experiments

Causal conclusions are not justified -> findings do not show that violent behaviour is determined by biology alone -> suggest psychological, cultural & situational factors play an important role in predisposition to violence

Readers may interpret findings and assume criminal behaviour is predetermined & inescapable

Research Techniques

Data was collected via PET Scans

Techniques have permitted researchers to study the brain in a way not possible until recently

In the past researchers relied on post-mortem examinations where brain physiology could not be linked to behaviour

PET Scans permit researchers to study detailed regions of the brain in action to be examined -> This meant Raine et al could see how the brains of different individuals differ in the way they process information

The Sample

The murderers were not typical of all violent people/individuals this is something Raine et al acknowledged

The finding do not show that all violent offenders have such brain dysfunction: the study can only draw conclusions about this kind of violent offenders -> an individual with some recognised form of mental impairment.

The crime is murder and many violent crimes do not involve murder

Conclusions are restricted to a very particular group of people

Evaluation: Alternative Evidence

Yany and Raine (2009) - meta-analysis of 43 imaging studies that considered both antisocial & violent behaviour -> Conclusion: There is significantly reduced prefrontal activity in antisocial and/or violent individuals

Further Supported by genetic studies that indicate a 'Criminal' gene -> MAOA causes abnormally high levels of dopamine

Tihonen et al (2015) analysed genes of 895 Finnish Prisoners & found an association between this gene & an increased likelihood of committing a violent crime

Genes are only a predisposing factor -> James Fallon analysed his own genes & found he had the genetic & brain characteristics of a violent criminal but he wasn't one -> Suggested it was because his positive experiences during childhood meant his criminal tendencies were not triggered

Ethical Issues & Social Implications

Valid Consent

May not have fully understood what they would be required to do

May have found performance task difficult which could have lowered their self esteem causing psychological harm

May have found PET Scan distressing if they did not realise that they would be involved in one

Murderers may not have been mentally competent enough to provide valid
consent

May not have understood their right to withdraw because they felt like they didn’t have a choice

Socially Sensitive Research (SSR)

Any research that has consequences for the larger group of which the participants are apart of (SSR)

Our understanding of criminal behaviour is advanced by SSR

If indication is born rather than made it may have consequences that would be disadvantageous for people with similar brain abnormalities