FORENSIC PSYCHOLOGY - Genetic and Neural Explanations Flashcards
Describe the study of Christiansen (1977).
Christiansen studied around 3500 twin pairs in Denmark. He found that male and female monozygotic pairs had a higher criminal concordance rate than their dizygotic counterparts, although there was still a concordance rate (albeit much smaller.)
What were the concordance rates for Christiansen’s twins?
Monozygotic - Male: 35%, Female: 21%
Dizygotic - Male: 13%, Female: 8%
What does Christiansen’s study show us?
His study shows that there could be a genetic predisposition to criminality, due to the implications of the concordance between Monozygotic pairs. The gender differences also pose an interesting implication based on gender and criminal behavior.
What is the core criticism of the study?
The core criticism is that the rates are seriously low, below 40% for monozygotic pairs, and are meagre for the dizygotic pairs. This suggests that criminality could be in part down to genetics, but other factors in this study, may have had a much greater influence, for instance, pairs grown up in the same household would both have an equal or greater measure of nurture based influence for genetics to be an isolated factor in itself in the study.
What studies help in supporting the findings of Christiansen’s study?
Crowe (1972) found that 50% of adopted children with a mother with a criminal record, had themselves, a criminal record by the time they reached 18 years of age. In a control group where the biological mother did not have a criminal record, this figure dropped to 5%. Because they were adopted, this study negates the nurture of their biological family.
What neurotransmitters could cause criminality and why?
Dopamine: Addiction is rewarded by dopamine, which makes us feel gratification from its release. Because of substance abuse being included in this metric, it can be indirectly related to crime.
Serotonin: Low levels of are linked to aggression.
Cite a Dopamine and Serotonin based study into criminal behavior.
Dopamine: Buitelaar (2003) - Juvenile delinquents given dopamine antagonists reducing levels of dopamine, showed a decrease in aggressive behavior.
Serotonin: Scerbo and Raine (1993) - A meta-analysis on 29 pieces of research into anti-social adults and children, in all cases, they found low levels of serotonin.
Discuss the significance of the Amygdala and Frontal Lobe.
Amygdala: The Amygdala is an evolutionary part of the brain, linked to an interaction between emotion and aggression.
The Frontal Lobe: The Frontal lobe is a newer part of the brain. As such, it regulates the interaction between emotion and aggression.
Cite research based around the Frontal Lobe in this area.
Brower and Price (2001) found a link between frontal lobe dysfunction and violent crime.
Raine et al (1997) found in PET scans of 43 murderers/manslaughterers (2 were female)
