Biological explanations for criminal behaviour

• What type of study did Bower and Price conduct in 2001 regarding the frontal lobe?


  A meta-analysis of data from other research
• What relationship did Bower and Price (2001) find regarding the frontal lobes?


  They found a relationship between antisocial behavior and damage to the frontal lobes
• What functions are associated with the prefrontal cortex?

  Problem solving and decision making
• How might damage to the prefrontal cortex relate to aggression?

  Damage can impair problem solving and decision making, potentially leading to aggression
• What type of injury is associated with an increase in aggression according to Bower and Price (2001)?

  Focal orbitofrontal injury
• What did Bower and Price (2001) find regarding brain damage in relation to violent crime?


  They found no evidence linking brain damage in these areas to violent crime
• What type of criminal acts were linked to brain damage according to Bower and Price (2001)?

  Impulsive criminal acts
• How is aggression defined in the study material?

  As threatening behavior or physical assault directed at someone else or the environment
• How is violence defined in the study material?

  As actions that inflict physical harm in violation of social norms
• Blumer (75)- Cited by Bower and Price. Anti social personality can arise from damage to the frontal lobe, damage tends to be in the orbitofrontal lobe. Poor control over impulses, outbursts, lack of interpersonal sensibility. There are studies which found this change improved over time (Labette 1997). Case studies have issues with validity as it is impossible to see what the patient was like before the injury in order to see a good casual relationship.
• Diaz: Traumatic brain injury (TBI) and association with crime (1995)- Looking at the insanity defence, both from structural and functional issues. Most damage done to frontal, temporal lobes and brain stem. FL related to anti social behaviour. Cited Volkow and Tancredi (1987) 2/4 violent psychiatric patients showed FL damage using a PET scan. There were also individual differences in brain damage.
• Huw Williams (2012)- The youth are at a greater risk of TBI 8.5%. Daily mail claimed those with ABI can behave in a 'criminal way'. 60% of young adult male prisoners in custody having a TBI. Youth brains aren't fully developed (25) impulse control is the last to develop. Find 50-80% of young offenders have TBI compared to 10% of the general population.
• XYY- 1 in 1000 males are born with an extra Y chromosome so they have 47 chromosomes. This leads to the males being slightly taller than their siblings, and having a slightly lower intelligence than their siblings. XYY can also lead to the males being more impulsive, and having behavioural problems. Some XYY males are also more physically active, all of these can lead to anti social behaviour. It is interesting to note John W Gacy was XYY.
• What year did Theilgaard conduct his study on blood samples?


  1984
• How many men were included in Theilgaard's study?

  30,000
• In which decade were the men born that were studied by Theilgaard?


  1940s
• How many men in Theilgaard's study had the XXY abnormality?

  16
• Charles Whitman (1966)- Marine, Texas tower sniper. Killed 16 (a 17th died 35 years later from injuries sustained) Wounded 31. Forensic investigators have theorized that the tumour pressed against Whitman's amygdala, a part of the brain related to anxiety and fight-or-flight responses​
• How many men in Theilgaard's study had the XYY abnormality?


  12
• What types of data were collected from the men in Theilgaard's study?


  Criminal history, background, intelligence, and personality
• Who conducted the interviews in Theilgaard's study?

  A social worker who was unaware of the study's aim
• Why did Theilgaard use a social worker for the interviews?


  To avoid the problem of researcher bias
• What was found regarding the intelligence levels of XYY males in Theilgaard's study?


  XYY males had slightly lower levels of intelligence than average
• How did XYY males tend to behave towards others according to Theilgaard's findings?


  They tended to be more aggressive towards other people
• What did Theilgaard conclude about the similarities between XXY and XYY males?


  There were far more similarities than differences between XXY and XYY males
• What was the conclusion regarding the existence of a criminal gene in Theilgaard's study?

  No solid evidence of a criminal gene was found
• Positives of Theilgaard- No bias. Lots of qualitative and quantitative data ( validity). Triangulation.
• Negatives of Theilgaard- Small sample, cost