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  • 1. Theories of Biology Raine, Bruner, Daly and Wilson
  • 2. The theory of biology • The basic assumption here is that criminals are biologically different to non-criminals. In particular, some bio-psychologists argue that special structures inside the brain control our social behaviour. People without these structures may become criminals. • However, these theories are often reductionist and deterministic and can only explain certain types of crime.
  • 3. Evolution: • It has been shown that males often commit crimes more than females. • It has been suggested that this could be due to an evolutionary trait. • Males who were aggressive, could fight, run and take risks, etc, would survive more in times when such behaviours were necessary, those who were not aggressive died and so the necessary genes were passed on.
  • 4. Raine Brain abnormalities in murderers indicated by PET
  • 5. Background: • Earlier work by Raine indicated a relationship between low levels of activity in the prefrontal cortex and violent behaviour. • This is an area of the bran behind the forehead and is often described as being the ‘emergency break on behaviour’, as it prevents us from acting on violent or aggressive impulses.
  • 6. Aim: • To investigate patterns of brain activity in murders compared to a matched sample of non- murders using PET scanning.
  • 7. Participants: • An experimental group of 41 participants charged with murder or manslaughter who had pleaded not guilty for reasons of insanity- NGRI- but had been convicted. • Mean age of 34.3. • 39 men and 2 women. • 23 had a history of brain damage, 6 had schizophrenia, 3 substance abuse, 2 affective disorders, 2 epilepsy, 3 learning difficulties and 2 with paranoid personality disorders. • A control group of 41 people matched on sex and age, mean of 31.7 years, and were similar in other ways- 6 schizophrenia etc.
  • 8. Procedure: • Participants were screened and showed no history of psychiatric illnesses. • No participants were currently on medication. • The IV was whether a participant was a murderer or not, and the DV was the measures of brain activity and brain structure found using the PET scanner.
  • 9. What is a PET scan? • A brain Positron Emission Tomography can is an imaging test that uses a radioactive substance to look for disease or injury in the brain. A small amount of this material is given through the vein on the inside of the elbow. It travels through the blood and collects in organs and tissues. It helps the radiographer to see certain areas more easily. • The PET scanner detects signals from the tracer and a computer changes this into a 3D image.
  • 10. Findings: • There was no difference in task performance, but significant differences in the brain metabolism of glucose in a number of areas between murderers and non-murderers. Area of the brain Findings Prefrontal cortex Lower glucose metabolism- less activity- in some areas. Limbic system Different levels of activity in the amygdale and hippocampus. Corpus callosum Less activity
  • 11. Conclusions: • The study shows that murderers pleading NGRI have significant differences in glucose metabolism in certain areas of the brain compared to the non-murderers. • Reduced brain activity in certain areas may be one of the many predispositions towards violence. • The areas identified as having abnormal activity are associated with; a lack of fear, lower self- control, increased aggression, impulsiveness, problems controlling and expressing emotions.
  • 12. Issues: • Ecological validity – Used real criminals as well as a control group • Generalisability – Can only be generalised to violent criminals • Usefulness – Can be applied to trials – Can help with rehabilitation after brain injuries
  • 13. Debates: • Free will vs Determinism – Brain structure determines criminality • Nature vs Nurture – Biology changes in the structure of the brain lead to criminal behaviours
  • 14. Bruner A study of violence in a family of genetic abnormality.
  • 15. Background: • Genes are the building blocks of DNA and tell our bodies how to grow and develop. • Our genes do not know anything about the laws and constructs of society so criminality is not directly affected by our genes. However, genes can give people predispositions- a natural, built-in tendency to behave in a certain way- for example taking risks, being aggressive or selfish. • These predispositions may lead to a person behaving in a way that leads to criminal behaviours.
  • 16. Aim: • To study a family where males were affected by a syndrome of borderline mental retardation and abnormal violent behaviours.
  • 17. Methodology: • A case study of a family from the Netherlands. • 5 affected males were studied who showed behaviours such as impulsive aggression, arson, attempted rape and exhibitionism. • Data was collected from the analysis of urine samples collected over a 24 hour period.
  • 18. Findings: • The tests showed disturbed monoamine metabolism associated with a deficit of the enzyme monoamine oxidase A. • A mutation was identified in the X chromosome of the gene responsible for the production of MAOA.
  • 19. Conclusions: • MAOA is involved in serotonin metabolism. • An impaired metabolism of serotonin is likely to be responsible for mental retardation and could be linked to the aggressive behaviour.
  • 20. Issues: • Generalisability – Small sample- only 5 boys from 1 family – Could this just be an ‘odd’ family?- not like the rest • Quantitative data – Urine samples were taken which increases the objectivity.
  • 21. Debates: • Reductionism vs Holism – Puts behaviours down to genes and mutations within the body • Psychology as science – Objective measures
  • 22. Daly and Wilson Investigation of gender-related life-expectancy.
  • 23. Background: • In all cultures, young males appear more often in crime statistics than any other group. • Daly and Wilson noticed that young male offenders have a short term horizon where they want instant gratification. They also have a short lifespan expectation die to the risky behaviour that they engage in.
  • 24. Aim: • To find out if homicide rates would vary as a function of local life expectancy in Chicago.
  • 25. Methodology: • A correlational study using survey data from police records, school records and local demographic records in Chicago.
  • 26. Why Chicago? • Chicago is an unusual American city because it is divided into 77 distinct community areas or neighbourhoods. • These areas have fairly clear cut boundaries and their own social and economic characteristics. • The researchers took their data from a recent population census and compared it to police and school records on crime, delinquency and truancy. • They focussed on the communities that had a low average life expectancy for males aged 54-77 years.
  • 27. Findings: • The results showed that life expectancy was a good predictor of neighbourhood homicide rates. • There was a negative correlation; the lower the life expectancy, the higher the homicide rate. • The correlational coefficient was -0.88, which is very strong. • Daly and Wilson suggest that young men in these areas have the ‘short term horizon’ described earlier. They want instant gratification rather than delayed pleasure and expect to live short lives and discount the future.
  • 28. Findings: • Another finding was a negative correlation between truancy from school and life expectancy. This could be explained by a short term horizon again. – The boys see little point in working hard at school because they do not imagine long futures for themselves and their parents don’t force them to attend because they also operate on a short term horizon. – The payoff is then that young males who skip school and break the rules will have more potential friends, compensating for them dying younger.
  • 29. Conclusions: • Young men from disadvantaged neighbourhood expect to live shorter lives, therefore are more likely to engage in risky behaviours. • These findings can be explained by social factors such as poverty and inequality.
  • 30. Issues: • Correlational study – Does not show cause and effect • Reliability – Data gathered from police and school records
  • 31. Debates: • Ethnocentrism – Only used people from Chicago • Reductionism vs Holism – Biological explanations • Free will vs Determinism – Biology determines behaviours

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