Criminal Behaviour- Biological Explanations Flashcards
Inherited Criminality
The idea that criminality can be passed down through genetics.
Genetic factors
One or more genes predispose individuals to criminal behaviour. Evidence for this comes from twin studies where non identical (DZ) and identical (MZ) twins are compared.
Raine (1993)– Reviewed research on the delinquent behaviour of twins and found a 52% accordance for MZ twins compared with 21% for DZ twins.
Searching for candidate genes- 2 genes are linked to criminal behaviour. Monoamine oxidase A (MAOA), and Cadherin 13 (CDH13).
Brunner et al. (1993)– Analysed the DNA of 28 male members of a Dutch family with a history of violent and criminal behaviours e.g rape and attempted murder. The men shared a particular gene (the warrior gene) that led to abnormally low levels of MAOA.
Diathesis Stress
Current thinking in terms of epigenetics proposes an interplay where genes are switched on or off by epigenomes which, in turn, have been affected by environmental factors. A diathesis-stress. One possibility is maltreatment in childhood.
Caspi et al. (2002)– Used data from the longitudinal Dunedin study. This followed 1037 people from when they were babies in the 70s. They assessed antisocial behaviour at age 26 and found 12% of men with the low MAOA gene had experienced maltreatment in childhood and were responsible for 44% of violent crimes.
Differences in the brain
Criminal genes may cause differences in areas of the brain, or differences in key neurotransmitters.
Raine (2004)–Cited 71 brain imaging studies, showing murderers, psychopaths, and violent individuals that had reduced functioning in the prefrontal cortex. This is the area of the brain that is involved in regulating emotion and controlling behaviour and moral behaviour in general. Lowered activity in this area is associated with impulsiveness and loss of control.
Seo et al. (2008)– Suggest that low levels of the neurotransmitter serotonin may predispose individuals to impulsive aggression and criminal behaviour, partly because this neurotransmitter normally inhibits the prefrontal cortex. Dopamine hyperactivity may enhance this effect. Both very high and very low levels of noradrenaline have been associated with aggression, violence and criminality according to Wright et al. (2015). Noradrenaline helps people react to perceived threats, so low levels would reduce this ability.
Inherited personality
Eysenck’s theory, some people inherit types of behaviour that predispose them to behaving in a criminal way.
Evaluation- Research support from adoption studies
Crowe (1972) found adopted children who had a biological parent with a criminal record had a 38% greater risk of having a criminal record by 18. Adopted children whose mother didn’t have one only had a 6% risk. Mednick et al. (1987) looked at 14k adoptees, and found 15% of sons adopted to criminal families went on to be criminals compared with 20% whose biological parents were criminal- inherited genes are more significant.
Evaluation- Deterministic approach
The evidence above shows criminality cannot be 100% explained in terms of genetics. Stephen Mobley’s lawyers used this to excuse his crime. Tihonen et al. (2015) said those with the defective gene were 13 times more likely to have a history of violent behaviour, but this means not everyone with the gene had become criminal. On the other hand, it could be said that the cause of this behaviour would be outside a person’s control- at the very least it is harder for some individuals to avoid criminal violence.
The Role of the Amygdala
The amygdala is a section of the brain that is responsible for detecting fear and preparing for emergency events. This lesson discusses the amygdala, its functions, and its role in our perception of fear and other emotions.
Types of aggressive behaviour
Proactive and reactive.
Proactive-Cold-blooded, planned, and premeditated.
Reactive- Hot-blooded, angry and stems from physiological arousal.
What and where is the amygdala?
Structure and function of the amygdala
It is a collection of neuron cell bodies and grey matter in the brain that is densely packed together into a cluster of 13 nuclei. It is found in the medial temporal lobe, part of the limbic system.
It is neurally linked to the hypothalamus, hippocampus, prefrontal cortex and other parts of the brain. It has widespread influence on brain functioning and behaviour associated with emotion, motivation, and social interaction in both human and non-human animals. It plays a major role in how we assess and respond to environmental threats, hence its importance in determining aggressive behaviour.
Research
Coccaro et al. (2007)- Looked at the effects of the amygdala on aggression by studying people with Intermittent Explosive Disorder (IED). Each participant was shown images of faces whilst having a fMRI scan. Differences were found when compared with non-IED controls. Those with IED showed high amygdala activity when shown angry faces. This showed an association between amygdala activity and processing aggressive emotions. This study has high realism.
Gao et al. (2010)- As children, we learn to inhibit our aggressive and anti-social behaviours as through conditioning we learn that aggression leads to punishment. The amygdala is involved in processing information and fear conditioning. If you have a dysfunctional amygdala, it means you would be unable to identify social cues that indicate threats. For example, angry faces, and would not be able to link punishment and aggressive behaviour, as fear conditioning is disrupted.
Evaluation- Longitudinal studies on the amygdala
Pardini et al. (2014) studied 503 males who had been part of an earlier study when they were 6 or 7. 20 years later they identified 56 men who had shown aggressive behaviour since childhood, including involvement in serious criminal violence. fMRI scans were used to measure amygdala volume. High levels of aggression over the 20 year period were associated with lower amygdala volumes. The association persisted in a follow-up study 3 years later. This cannot be explained by confounding variables or by earlier levels of aggressive behaviour as they were all controlled. This is support for the role of the amygdala in aggressive behaviour and is especially valuable because it is evidence of the predictive validity of the explanation. It shows that differences in amygdala volume may predict future aggressive behaviour and involvement in crime.
Evaluation- Other brain areas are important
The amygdala is part of a wider system of connected brain structures and does not operate on its own to determine aggressive criminal behaviour. It functions together with the orbitofrontal cortex. Raine et al. (1997) investigated murderers who had used an overwhelming degree of reactive, hot-blooded aggression in their crimes. These individuals had higher glucose metabolism in their amygdala but abnormally low metabolism in the prefrontal cortex. This demonstrates how complex the regulation of aggressive criminal behaviour is. It involves at least 3 important brain structures. The amygdala, orbitofrontal cortex and the neural connection between them. Dysfunctions of the amygdala may not be enough on their own to account for criminal behaviour. The neurology of aggressive crime is complex and risks being over-simplified by a focus on the amygdala only. Criminal behaviour is the outcome of many infleunces involving the neural connectivity between several brain structures and areas.
