FORENSIC PSYCHOLOGY - biological explanations - genetics and neural

Question 1

Explain how genes explain offender behaviour?

Answer 1

Offenders, inherit a gene that predispose them to commit a crime.

Question 2

Explain Christiansen (1977).

Answer 2

• studied over 3500 twin pairs in Denmark
• found concordant rates of offender behaviour for 35% of monozygotic twins and 13% for dizygotic twins.

Question 3

Explain Crowe (1972)

Answer 3

• found adopted children whose biological mother had a criminal record had 50% risk of having a criminal record by 18.
  WHEREAS = adopted children who had a biological mother that didn’t have a criminal record only had a 5% risk.

Question 4

Explain Tiihonen et al (2015) on candidate genes.

Answer 4

• genetically analysed 800 finish offenders
• FINDINGS = two genes may be associated with Violent.
  1. MAOA = regulate serotonin in the brain + linked to aggressive behaviour
  2. CDH13 = linked to substance abuse and attention deficit hyperactivity disorder(ADHD)
  FINDINGS = 5 to 10% of survey violent crime in Finland attribute to MAOA and CDH13 genotypes.

Question 5

Explain the diathesis stress model on why offender behaviour is determined by genes.

Answer 5

The genes may influence offending, however they need to be triggered by the environment. Combination of genetic predisposition and biological or psychological trigger can create a tendency towards offending behaviour.

Question 6

What is the neural explanation?

Answer 6

Any explanation of behaviour in terms of functions of the brain and nervous system. Includes activity of prefrontal cortex and neurotransmitters.

Question 7

Explain Raine (2011) on the influence of the prefrontal cortex on behaviour.

Answer 7

• individuals with antisocial personality disorder (APD) showed reduced activity in the prefrontal cortex ( regulates emotional behaviour )
  FINDINGS = 11% reduction in volume of grey matter in the pre-frontal cortex of people with APT compared to control groups.

Question 8

Explain Keyser(2011) on the influence of mirror neurons in offenders.

Answer 8

• when criminals were asked to empathise with others, their empathy reactions activate.
• this is controlled by mirror neurons
• they have a neural switch that can be turned on and off unlike the ‘normal brain’ which has empathy switch permanently turned on.

Question 9

Evaluate genetic explanation.

Answer 9

+ support for DIATHESIS STRESS = Mednick et al = studied 13,000 Danish adoptees.
When biological and adopted parents had no convictions = 13.5% of adoptee did
When biological parents had convictions = 20% of adoptees did
When both adoptive and biological parents had convictions = 24.5% of adoptee did.
= genetic inheritance plays an important role in offending but environmental influence is also important

• issues with twin evidence = research is assumed that twins are brought up together in the same environment but this mostly applies to MZ twins and DZ twins because they are identical and parents treat them more similarly than DZ twins. = increase in concordance rate in MZ is due to much more similarity than DZ.

Question 10

Evaluate neural explanations.

Answer 10

+ BRAIN EVIDENCE = support for the link between crime and the frontal lobe.
Eg Kandel and Freed (1989) = found that damage to frontal lobe causes impulsive behaviour and emotional instability. = frontal lobe is associated with planning behaviour supporting the idea that brain damage is a causal factor..

• INTERVENING VARIABLES = Farrington et al found that factors from childhood such as being raised by a convict parent and being physically neglected can cause APD. Therefore there are other intervening variables that have an impact and relationship between APD and offending is complex.