As dooming and pessimistic as it is, crime is an inevitable and ongoing constant in most societies, the causes of which are fairly complex. Whilst we aren’t here to analyse why crime exists and the very philosophy of it, we can very well look at the psychology of criminals, and at theories that may explain why they behave as such: the biological factors behind it is an especially important explanation.

We have already looked at the Nature vs Nurture debate, in which Hans Eysenck and his criminal personality theory was briefly brushed upon. This can be delved into further, by compiling key biological components of how people develop their personalities in the first place, and in turn, how this differs from individuals with a criminal personality.

First and foremost to recap, in 1947 Hans Eysenck used the nature explanation to infer that the impulse to behave in a criminal manner was innate. He asserted that the Central Nervous System (made up of the brain and spinal cord) was what determined our personalities, and therefore our behaviour.

The key aspects of personality in this sense are psychoticism (characterised by aggression, impulsivity, and antisocial behaviour), extraversion (characterised by sociability) and finally neuroticism (characterised by emotional states, insecurities and anxiety). In a questionnaire that evaluated these traits, a criminal identification was produced by a score over 70% in all 3 personality types, in psychoticism alone or in any 2 personality types. (PEN Personality)

To date, most researchers agree on the significance of extraversion and neuroticism but there is less consensus on the remaining trait. Whilst it may still play some role in personality, its central importance may have been overestimated by Eysenck.

It is sections of the brain that have disparities between its normal function and how it is projected to be in individuals with a criminal personality.

• The Reticular Activation System and Cerebral Cortex – The first is a neural network whilst the latter is the outer layer of the brain, but both are important for mediating consciousness and alertness. The RAS regulates the stimuli sent to the cerebral cortex. This is under aroused in extraverts creating a desire for more stimulation and consequently resulting in aggressive, risky and lawless behaviour.

• Dopaminergic Neurons – In the CNS these are a collection of nerve cells that synthesize the neurotransmitter dopamine. Psychoticism is the result of an excess of this and due to the fact that dopamine is associated with pleasurable sensations, this leads to the inhibition of impulses in the brain during synaptic transmission. Within a criminal personality, the person does not fear the consequences of their actions so have no hesitation to commit a crime.

• Dopamine Reward System – this neural network is responsible for people experiencing elation and pleasure. As necessities and rewards drive human actions, this is important for our brains to compute the value of a reward in order for it to be translated into an action. Extraverts respond more positively to reinforcements like money or sex to such an extent that overproduction occurs in the DRS for a criminal personality. In turn, those individuals feel they need acquire those reinforcements illegally.

• Automatic Nervous System – this is responsible for the unconscious control of the body’s internal organs. Though the initial function isn’t particularly exciting, its activity is related to neuroticism. It will be activated during emotion-educing situations. The ANS regulates the activity of the brain’s limbic system (a neural network that controls emotional expression), which is over aroused in neurotics leading to higher levels of violence, under the emotional instability associated with a criminal personality.

The PEN personality has strong links to how we are socialised and integrated into society. Our upbringings involve punishments and consequences for certain behaviours that provokes an association between the two. There is a further anxiety of being punished with relations to the action itself. With a high PEN score (over 70%) individuals are thought to have a biological nervous system that is more difficult to socialise since they don’t naturally form connections between antisocial behaviour and the anxiety of experiencing consequences. They are sensation-seeking, quick to react, and lack empathy. Hence, behaviours that are typically illegal and risky are perceived as exciting and punishment is ineffective.

Against the existing evidence of links between the PEN personality and criminal behaviour, the deterministic nature of this explanation with disregard for individual differences, prevents it from being completely reliable. Even so, is it appropriate to suggest that a criminal’s personality and therefore actions can be completely narrowed down to a biological explanation, over which they have no control? Voice your opinion in the comments …

– Inayah Jannat