Theilgaard (1984)

Question 1

Aim

Answer 1

If criminals had a particular gene that could be responsible for their criminal behavior

Question 2

Procedure

Answer 2

• Took blood samples from a small sample of men
• XYY and XXY - chromosome abnormality were found
• The men with the chromosome abnormality were interviewed by a social worker about their backgrounds and criminal history.
• Given intelligence test
• A personality test to see if they showed more aggression than normal XY males

Question 3

Results

Answer 3

• XYY had slightly lower intelligence and tended to be more aggressive
• Could be evi

Question 4

Why he used a social worker

Answer 4

• Using an independent interviewer who did not know the aim, was able to avoid researcher bias
• Researcher bias = Researcher carries and interprets the study in a way they find out what they want to find out

Question 5

Conclusion

Answer 5

• Provides limited evidence for XYY males being more aggressive than XXY males. However, there are more similar and different

Question 6

Strengths (2)

Answer 6

1) All tests and interviews were done by a social worker who did not know the aim which avoided biased in reporting and would not have led the men to respond in a particular way
2) Used a wide range of tests to measure different aspects of the men’s lives and personality

Question 7

Weaknesses (3)

Answer 7

1) A small sample was used
2) Results cannot be generalized as we cannot be sure that all XYY are aggressive or have lower intelligence. Plus, since XYY males are fairly average, it is hard to pick out from other males and the chromosome abnormality is not inherited it cannot be easily tracked in families
3) Only a correlation between XYY males and aggression. This means chromosome abnormality may not have caused increased aggression as there could be other factors for aggression such as biological reasons.