Unit 2.1 (3.2 Evaluation included) Flashcards
What is the XYY theory?
It is a theory that is based on the idea that men with XYY are more aggressive and have a higher probability to commit violent crime.
Who pushed the XYY theory?
Jacobs (1965)
How useful is the XXY theory for understanding crime?
- The only real example is John Wayne Gacy who had XXY chromosomes.
- Some studies XYY men are over represented in prison.
- Overall, the XXY men tend to commit non-violent crime, not violent crime as the XYY hypothesis predicts (Epps, 1995).
What is the Twin Studies theory?
Aim to reveal the importance of environmental and genetic influences for traits, phenotype and disorders.
What were the two types of twins
Monozygotic (MZ) - one fertilized egg, share 100% of DNA.
Dizyogtic (DZ) - from 2 seperate eggs and share 50% DNA.
What studies back Twin studies?
- Johannes Lange (1929) found a degree of cordence between MZ over DZ, small sample size.
- Christianisen (1977) studied 3586 twins from danish island, Cocordence rates of 35% for Mz twins and 13% of Dz twins.
What are issues with twin studies?
- Lange’s experiment is problematic small sample size and Mz/Dz satues not determined.
- If environment not properly controlled as a variable, it could affect results in study.
What were the aims of the adoption studies?
To separate environment from hereditary e.g how life effects twins.
What were studies that were based on the adoption studies?
Hutchings and Mednick (1975) - 14,000 adopted boys had a higher proportion of boys with criminal conviction had biological parents with convicts.
- Mednick et al (1994) - No relationship between number of adoptive parents criminal convictions and number of adopted convictions.
Evaluation of the adoption studies?
Good experiment design and fairly easy due to genetic similarities as a natural characteristics, environmental separation with adopted children.
Adoption process is not fully random, often matched with families that similar to bio.
Age of adoption needs to be considered and difficult to conducted on some groups due to bio parents information.
What was Sheldon theory?
That body type can affect likelihood to commit violent crime.
What were the 3 types of body types?
- Ectomorph - introverted and restrained.
- Mesomorph - extroverted and aggressive (most likely to be criminal)
- Endomorph - Extraverted sociable and cooperative.
How valid is Sheldon’s theory?
There does seem to be a very slight correlation between body type and criminality.
Could be argued that the judicial system may treat mesomorphs more harshly based on a stereotype, due to perceived strength.
Ectomorphs and endomorphs can also be criminals which is contradictory to Sheldon’s idea that mesomorphs are criminals.
Body types aren’t fixed throughout lives they can change.
What did Lombroso’s theory of ‘atavistic type’ include?
He claimed that criminality was inheritable, and that you could infer someone was a criminal based on look. e.g murderers had curly hair and bloodshot eyes.
What are the key issues with Lombrosos approach?
- Did not use control groups in studies
- Difficult to argue that criminality in inherited, as criminality is a social construct.
- This could be used to justify racist views of criminality.
