4. biological explanations: genetic and neural Flashcards
GENETIC
what did Christiansen do and find?
Christiansen studied over 3500 twin pairs in Denmark and found concordance rates for offender behaviour of 35% for identical twins (MZ) males and 13% for non-identical twin (DZ) males.
GENETIC
what did Crowe find?
Crowe found that adopted children whose biological mother had a criminal record had a 50% risk of having a criminal record by the age of 18, whereas adopted children whose biological mother didn’t have a criminal record only had a 5% risk.
GENETIC
What did Tiihonen do and find?
Tiihonen et al conducted a genetic analysis of 800 Finnish offenders and suggested that two genes may be associated with violent crime.
1. The MAOA gene: it regulates serotonin in the brain and has been linked to aggressive behaviour.
2. The CDH13 gene: linked to substance abuse and attention deficit hyperactivity disorder (ADHD).
The analysis found that about 5-10% of all severe violent crime in Finland is attributed to the MAOA and CDH13 genotypes.
GENETIC
what is the diathesis stress model for offending?
A tendency towards offending behaviour may come about through a combination of genetic predisposition and biological or psychological trigger. Even if genetics have some influence on offending, it is likely that it is at least partly moderated by the effects of the environment
GENETIC
AO3: give a strength of genetic explanations of offending
(SUPPORT FOR DIATHESIS-STRESS, Mednick)
There is support for the diathesis -stress model of offending.
A study of 13000 Danish adoptees was conducted by Mednick et al. When neither the biological nor adoptive parents had convictions, the percentage of adoptees that did was 13.5%. The figure rose to 20% when either of the biological parents had convictions, and to 24.5% when both adoptive and biological parents had convictions.
This shows that genetic inheritance plays an important role in offending, but environmental influence is clearly also important, providing support for the diathesis-stress model of crime.
GENETIC
AO3: give a limitation of genetic explanations for offending
(ISSUES WITH TWIN EVIDENCE)
The genetic explanation is an assumption of equal environments.
It is assumed by researchers studying twins that environmental factors are held constant because twins are brought up together, therefore must experience similar environments. However, this shared environment assumption may apply much more to MZ twins than DZ twins because MZ twins look identical, and people tend to treat them more similarly which in turn affects their behaviour.
This means that higher concordance rates for MZ twins is because they are treated much more similarly than DZ twins.
NEURAL
what did Keyser’s find about mirror neurones?
Keysers found that offenders’ empathy reaction controlled by mirror neurons only activated when offenders were asked to empathise. This suggests that APD individuals are not totally without empathy but may have a neural switch that can be turned on and off, unlike the normal brain which has the empathy switch permanently on.
NEURAL
Evidence suggests there may be neural differences in the brains of offenders and non-offenders.
what disorder is associated with offending?
Antisocial personality disorder (APD) is a condition that characteries many convicted offenders. It is associated with reduced emotional responses and a lack of empathy for others.
NEURAL
what did Raine find about the PFC?
Raine has reported that there are several brain imaging studies demonstrating that individuals with antisocial personalities have reduced activity in the prefrontal cortex (regulates emotional behaviour).
Raine also found a 11% reduction in the volume of grey matter in the prefrontal cortex of people with APD compared to controls.
NEURAL
AO3: give a strength of neural explanations for offending
(research support, Kandel and Freed)
There is research support for the link between crime and the frontal lobe.
Kandel and Freed reviewed evidence of frontal lobe damage and antisocial behaviour. People with such damage tended to show impulsive behaviour, emotional instability, and an inability to learn from their mistakes. The frontal lobe is associated with planning behaviour.
This supports the idea that brain damage may be a causal factor in offending behaviour.
NEURAL
AO3: give a limitation of neural explanations for offending
(INTERVENING VARIABLES - Farrington)
The link between neural differences and APD is complex.
Farrington et al. studied a group of men who scored high on APD. These individuals had experienced various risk factors during childhood, such as being physically neglected. It could be that these early childhood experiences that caused APD and some of the neural differences associated with it (e.g. reduced frontal lobe activity due to trauma.)
This suggests that the relationship between neural differences, APD and offending is complex and there may be intervening variables that have an impact.
