Biological explanations of criminal investigations

Question 1

What 2 genes are linked to criminality?

Answer 1

Monoamine oxide and cadherin 13

Question 2

What did Han Brunner et al investigate?

Answer 2

DNA of 28 Dutch males who impulsive and violent behaviours – shared MAOA ‘warrior gene’. Negative correlation reduced activity in the MAOA and CDH13 genes and increased criminal behaviour.

Question 3

What are Epigenetics? what do they propose? What’s an environmental factor?

Answer 3

Epigenetics – study of heritable changes in gene expression that does not involve changes to underlying DNA sequence. They propose an interplay between genes and environment where genes are switched on or off by epigenomes which have been affected by environmental factors – diathesis stress model. Environmental factors could be maltreatment in childhood. Caspi et al, longitudinal study of 1000 people – 12% with low MAOA gene had experienced maltreatment (responsible for 44% of violent convictions).

Question 4

What did Raine find?

Answer 4

71 brain imaging techniques showing murderers, psychopaths and violent individuals have reduced functioning in the prefrontal cortex. Lower activity is associated with impulsiveness and loss of control.

Question 5

What did Dongju Seo et al find?

Answer 5

low serotonin leads to impulsive aggression and criminal behaviour. Dopamine hyperactivity may enhance.

Question 6

What supporting research is there for inherited criminality?

Answer 6

Twin studies = monozygotic twins share 100% DNA. Dizygotic twins share 50% DNA. Raine found 52% concordance rate for MZ twins compared with 21% for DZ twins for delinquent behaviour. Suggests that if one MZ engages in criminal behaviour there is a 52% chance the other will. May explain delinquent behaviour. Most genetic research on criminal behaviour relates to the association between criminal and violent or aggressive behaviour. Biological explanations may just account for certain kinds of criminality. Psychopathy is inherited – Bruce Blonigen et al = genetic basis of psychopathy in 600 male and female twins. Explains some violent crimes through genetic inheritance.

Question 7

What did Wright et al find?

Answer 7

High/low noradrenaline associated with aggression, violence and criminality. This neuro helps people react to perceived threats.

Question 8

What methodological issues are there for inherited criminality?

Answer 8

Comparing MZ and DZ twins could control environmental effects. Environments for MZ twins are more similar than dz. This could mean the difference in concordance rate could simply reflect environmental differences.

Question 9

Why is inherited criminality only a partial explanation?

Answer 9

Unable to explain no violent crime which makes it difficult to argue that it can simply be explained in terms of genetics. Environmental cause?

Question 10

What’s an alternative explanation for inherited criminality?

Answer 10

Many criminals report having some brain injury – 8.5% Americans have brain injury with 60% in us prisons. Differences due to nurture and not nature (Harmon et al).

Question 11

What are the 2 main types of aggressive behaviour?

Answer 11

Proactive = cold blooded, planned and premeditated. Reactive = hot blooded, angry, physiological arousal.

Question 12

what is the amygdala? Where is it located? Who was it first implicated by?

Answer 12

small, almond shape. 2 amygdalae in each side of the limbic system in front of the corresponding hippocampus in its respective temporal lobe. Located in the medial temporal lobe. Involved with emotions.
first implicated in emotional behaviour by James Papez and Paul Maclean.

Question 13

What is the amygdala neurally linked to?

Answer 13

hypothalamus, the hippocampus and the preforntal cortex. It plays a major role in how we assess and respond to environmental threats.

Question 14

What did Emil coccaro et al find?

Answer 14

studied people with intermittent explosive disorder. Viewed images of face at the same times as having an fMRI. People with IED showed high levels of amygdala activity when they viewed angry faces.

Question 15

What did Yu Gao and colleagues find?

Answer 15

learn as children to inhibit our aggression and antisocial behaviours through fear conditioning. Amygdala is involved in processing fear information and fear conditioning. A dysfunction of the amygdala – can’t identify social cues that indicate threat. Don’t link punishment to their behaviour. Seem fearless, overly aggressive and antisocial. Demonstrated in a longitudinal study of 1,795 ppts, tested at 3yrs. Used physiological arousal in response to painful noise. 20 years later involved in criminal behaviour – showed no fear conditioning at 3yrs.

Question 16

What supporting research is there for the amygdala?

Answer 16

Katrina Gospic – ultimatum game. Ppts played the role of the responder while undergoing fMRI scans. Found that when responders rejected unfair offers, amygdala activity was heightened and quicker. Sedative drug given before the game had 2 effects – reduced aggression and reduced amygdala activity.
Dustin Pardini – 503 males, 20 years later, subgroup of 56 men who shown aggressive behaviour since childhood. FMRI scans measure amygdala activity volume. High levels of aggression associated with lower amygdala volumes. Cannot be explained by potential confounding variables. Evidence of predictive validity. Shwos differences in amygdala volume may predict future aggressive behaviour and crime

Question 17

Why is the Amygdala only a partial explanation?

Answer 17

Amygdala functions with orbitofrontal cortex – thought to influence self-control, regulate impulsive behaviour and inhibit aggression.
Raine = hot blooded murders had higher glucose metabolism in their amygdala but abnormally low metabolism in the prefrontal cortex. Involves 3 important brain structures – the amygdala, the OFC, and the neural connection between them. Complex and risks being oversimplified.