16.3.1 Eysenck's Theory of criminal personality

• Personality theories are based on the idea that traits which are fixed (i.e. in place) from birth contribute hugely to subsequent behaviours e.g. aggression, violence, deception
• Eysenck was one of the prominent psychologists in the field of personality research: his concept that personality can be measured via dimensions is still used widely today in fields such as recruitment/human resources, counselling and therapy
• Eysenck’s (1973) Personality Inventory (EPI) originally proposed that personality exists along two dimensions: introversion/extraversion (E) and neuroticism/stability (N) - personality is measured according to how far along the dimension each person falls
• Eysenck later added the dimension of psychoticism (P) which is highly relevant to the measurement of criminal personality
• These personality dimensions - although psychological -  have a (tenuous) biological basis: extroverts are said to have an under-active nervous system which means that they require excitement to increase neurotransmitters such as noradrenaline and dopamine
• Introverted individuals are less likely to commit crime as they do not seek stimulation/arousal and they shun contact with other people, preferring a ‘quiet life’
• Neurotic individuals are more inclined to crime as they tend to be overly anxious, easily stressed, unpredictable and nervy
• Psychotic individuals are probably the most aligned with universally agreed-upon criminal tendencies being aggressive, manipulative, cruel, irresponsible, impulsive and prone to risk-taking 
• The EPI is a questionnaire which measures the above dimensions: it can be used to determine the extent to which a person can be described as having a ‘criminal personality’
• The EPI uses a dichotomous scale to measure each dimension, asking questions with Yes/No responses such as: 
  • Do you often long for excitement?
  • Are you usually carefree?
  • Do you find it very hard to take no for an answer?
  • Do your moods go up and down?
  • Would you do almost anything for a dare?
• Someone with a criminal personality would score high on the dimensions of extraversion, neuroticism and psychoticism i.e. they engage in risky behaviours as a result of their high extraversion; they are more likely to be impulsive as a result of their neuroticism and they lack guilt and empathy as a result of their psychoticism
• Eysenck claimed that the above combinations of personality traits are the reason why some people commit crime 

Eysenck’s (original) Personality Inventory.

Research which investigates Eysenck’s theory of criminal personality

• Singh & Rani (2017) tested 100 criminals and 100 non-criminals on different personality traits using the EPI and found that criminals scored higher on extraversion, neuroticism and psychoticism with the the key predictors of criminal personality being unhappiness, anxiety, feelings of inferiority, risk taking, irresponsibility, assertiveness and impulsiveness 
• Singh (1980) compared 50 female truants with 50 female non-truants aged 16 and found that the truants scored higher on neuroticism and extraversion, suggestive of psychopathic characteristics such as lack of socialisation, impulsivity, distrust of authority, tendency to blame others, and disregard for social norms

Evaluation of Eysenck’s theory of criminal personality

Strengths

• The EPI is a standardised measure which is easy to replicate in large numbers which means that it has good reliability
• Eysenck’s theory attempts bridge both biological and psychological explanations for criminality which goes some way towards offering a holistic view of criminality

Weaknesses

• Human behaviour is unpredictable, fluid and does not necessarily fit neatly into dimensions so in this regard there is some argument for the EPI being reductionist and limiting
• Eysenck’s theory provides the ‘what’ of criminal behaviour i.e. the dimensions across which it might be measured, but not the ‘why’ i.e. the theory lacks explanatory power

Link to Issues & Debates:

As noted above, the theory could be said to be an attempt at marrying biological and psychological explanations of criminality together but ultimately it rests on a Yes/No self-report which has more in common with reductionist measures. Any attempt to definitively categorise human beings is ultimately a fruitless endeavour as there is no such thing as a person having ‘a’ personality: each individual could be said to possess personality traits from all across the dimensions offered by Eysenck (and beyond) which are subject to change and fluctuation.

Eysenck’s theory is nomothetic as it attempts to determine general laws rather than considering that criminality is a highly personal and subjective behaviour which is probably better understood using idiographic methods.