Hans Eysenck was a research psychologist and temperament theorist. He used factor analysis techniques to develop theories of temperament – that part of the personality we are born with. His original work produced a set of two temperament distinctions, introversion / extroversion and neuroticism. Later, when he began to study patients in mental institutions, he added another dimension to his temperament scale; psychoticism (Boeree, 1998; Hollin, 1992).
Many other researchers and psychologists have developed theories similar to Eysenck’s and have also made uses of factor analysis research techniques to extend the study of criminal behaviour (Anastasi, 1988; Darley, Glucksberg & Kinchla, 1991; Hollin, 1992; Link & Mealey, 1992). So, what are Eysenck’s theories about and how has his work added to the study of criminality?
Eysenck determined there to be three major dimensions of temperament: Extroversion/Introversion, Neuroticism, and Psychoticism. He also noted that not only do all three factors decline with age but also that most people will have a mixture of temperament types. A person’s temperament is unlikely to be at the extreme edge of measurement in any one dimension i.e., there is a sliding scale of each dimension and each dimension can be present in varying amounts. Therefore, someone can score high on the neuroticism scale and low on psychoticism (Boeree, 1998; Hollin, 1992).
If someone is classed as an extrovert, they are sociable, like parties, have many friends and prefer talking to people rather than being alone. Extroverts like to take risks, they crave excitement and can act on the spur of the moment, thus they are generally fairly impulsive. Introverts, on the other hand, are quiet and enjoy their own company. They prefer books to people, have fewer friends but sustain deeper relationships, they are somewhat serious and like a structured, orderly life.
Neuroticism, or instability, is made up of a number of factors such as anxiousness, depression, feelings of guilt, low self-esteem, tenseness, irrationality, being shy and moody, and emotional. Stability, then is the absence of these traits. Aggression, coldness, egocentricity, an impersonal attitude, impulsivity, antisocial behaviour, lack of empathy, creativity, and a tough-minded attitude characterize people with high levels of psychoticism (Link & Mealey, 1992; Hollin, 1992). Those people with low levels of psychoticism are empathic, unselfish, altruistic, warm, peaceful, and pleasant. Eysenck found that women tend to have higher neuroticism scores than men. In addition, men score much higher in psychoticism than do women (Hollin, 1992).
Eysenck argued that certain biologically based personality features, that are inherited, are more prone to antisocial behaviour when they interact with various socialization processes. He further proposed that, combined with our autonomic and central nervous system characteristics, these biological factors affect our responsiveness to punishment and our predisposition for antisocial behaviour and experiences (Boeree, 1998; Hollin, 1992; Holman & Quinn, 1992).
Eysenck theorized that criminality and antisocial behaviour are both positively and causally related to high levels of psychoticism, extroversion and neuroticism (Holman & Quinn, 1992; Hollin, 1992; Vaughan and Hogg, 2002). The theory says that in extroverts, and possibly also in people high on the psychoticism scale, biologically determined low degrees of arousal and arousability lead to impulsive, risk-taking and sensation-seeking behaviour that increase the level of cortical (brain) arousal to a more acceptable and enjoyable amount (Holman & Quinn, 1992). Eysenck did find that extroverts experience cortical under-arousal, prefer higher levels of stimulation, and are less responsive to punishment – they therefore do not learn behavioural alternatives with the use of disciplinary action (Darley et al, 1991).
Eysenck first postulated then documented that sociopathy in particular was correlated with high scores on all three of the personality dimensions of the Eysenck Personality Questionnaire – extroversion (the opposite of introversion), neuroticism (the opposite of emotional stability), and psychoticism (psychopathy, not psychotic mental illness). All three of these dimensions exhibit substantial inheritability, and since psychoticism is typically much higher in males than females, it is a likely candidate for one of the relevant gender-limited traits which fits Cloninger’s two-threshold risk model explaining the sex difference in expression of sociopathy (Link & Mealey, 1992).
To try and explain the connection between temperament, delinquency, sociopathy, and criminal behaviour, Eysenck and colleagues devised the “General Arousal Theory of Criminality” and determined that a person’s behavioural predispositions are based on the inheritance of a nervous system which is insensitive to low levels of stimulation (Hollin, 1992). Individuals of such a type will be extroverted, impulsive, and sensation-seeking, because under conditions of relatively low stimulation they find themselves at a suboptimal level of arousal. To increase their arousal, many will participate in high-risk activities such as crime (Boeree, 1998; Link & Mealey 1992; Hollin, 1992).
In general support of this model, Ellis (1987) performed a meta-analysis which found that both criminality and sociopathy were associated with childhood hyperactivity (in the past), recreational drug use, risk-taking, failure to persist on tasks and a preference for wide-ranging sexual activity – all known indicators of suboptimal arousal. As Eysenck’s Personality Questionnaire is easy to administer, his theory regarding personality and criminal propensity, is easy to test (Hollin, 1992) and many psychologists have done so (Darley et al, 1991; Link & Mealey 1992; Hollin, 1992).
Additional confirmation of the arousal model comes from Zuckerman (1980), who found a similar pattern of behaviour associated with his measure of sensation-seeking. Zuckerman showed that sensation-seeking as a temperament starts at an early age, shows a high degree of inheritability, decreases with age, and exhibits gender differences – with higher scores more often in males. Because it shows a relationship with both gender and age, sensation-seeking (and its presumed underlying underarousal) may also be a good candidate for a trait that can explain the distribution and expression of sociopathy. However, it has been argued by Furnham and Thompson (1991) that the findings for psychopathy reflect the type of questions asked (Hollin, 1992). Also, in 1987, Arbruthnot, Gordon & Jurkovic determined there was “no evidence of a relationship” between personality inventories and criminality (Goldsmith, Israel & Daly, 2003:72).
In 1982, Gray and Cloninger proposed updated versions of the Eysenck model in which the three personality factors are rotated and renamed (Link & Mealey, 1992). Gray names the three systems: the approach, or, behavioural activation system, the behavioural inhibition system, and the fight/flight system; Cloninger names them novelty-seeking, harm- avoidance, and reward-dependence. The three factors explain the same variance in personality as Eysenck’s original dimensions and have been shown to be independent and highly inheritable In addition to corresponding to brain function, these three factors were proposed to parallel the activity of three brain chemicals:
dopamine for behavioural activation (or novelty-seeking), serotonin for behavioural inhibition (or harm avoidance), and norepinephrine for fight/flight (or reward dependence)(Link & Mealey, 1992).
In particular, underaroused individuals have trouble inhibiting their behaviour when both reward and punishment are possible outcomes. In situations where most people would experience an approach-avoidance conflict, sociopaths and extroverts are more likely to approach. Because of their high levels of sensation-seeking, children with an underaroused nervous system will be more likely to get into trouble and when they do, they will be less likely to be affected by and learn from the consequences (Hollins, 1992; Holman & Quinn, 1992; Vaughan & Hogg, 2002).
In 1970, Christie developed a scale for measuring this subclinical variation in antisocial personality; he called it the “Machiavellianism” or “Mach” scale (Link & Mealey, 1992). According to Christie, one’s Mach score is calculated by compiling answers to Likert-format queries of agreement or disagreement with statements like “Humility not only is of no service but is actually harmful,” “Nature has so created men that they desire everything but are unable to attain it,” and “The most important thing in life is winning”. Adults who score high on the Mach scale lack of concern with conventional morality. Christie also found that children who score high on Machiavellianism have lower levels of empathy than their friends of the same age (Link & Mealey, 1992).
High Machs, like sociopaths, are more resistant to confession after cheating than are low Machs, and they are rated as being more plausible liars. Like sociopaths, high Machs are often referred to as cool or aloof. One can thus easily think of Machiavellianism as a low-level manifestation of sociopathy. It shows a significant correlation with Eysenck’s psychoticism and neuroticism scales and a correlation with serotonin levels (Link & Mealey, 1992).
Eysenck’s contribution to the study of criminality has been many pronged. He contributed by formulating research theories and testing large groups of participants – as did Allport before him (Kristal, 1979). Eysenck presented theories and procedures that other people could use and reformulate, therefore continuing and advancing the study of criminal behaviour (Anastasi, 1988; Darley, Glucksberg & Kinchla, 1991; Hollin, 1992; Link & Mealey, 1992). Eysenck, by regularly being controversial, also forced other researchers and clinicians to propose theories of their own and prove them. He regularly stretched and forced the boundaries of study into criminal behaviour by involving himself in ‘unpopular’ movements and causes, such as efforts to raise IQ by vitamin and mineral supplementation and the eugenics movement (Boeree, 1998; Gibson, 1980). He and his theories became unpopular in the 1990’s (Boeree, 1998) when trait theories were widely criticized for not explaining how behaviour was determined, only that it existed and was inherited to a degree (Zimbardo, 1979) so widespread is this, that many texts and papers no longer refer to Eysenck and his work.
REFERENCES
Anastasi, A. (1988), Psychological Testing. New York, USA: MacMillan
Andrews, D. and Bonta, J. (1994), Psychology of Criminal Conduct. Cincinnati, Ohio, USA: Anderson Publishing
Blackburn, R. (1993), The Psychology of Criminal Conduct. Chichester, England: Wiley
Boeree, G. C. (1998), Personality Theories; Hans Eysenck. Available from, http://www.ship.edu/%7Ecgboeree/eysenck
British Medical Association – BMA (1995), A Mind to Crime. British Medical Journal, 311, 956
Darley, J. M., Glucksberg, S. & Kinchla, R. A. (1991), Psychology. New York, USA: Prentice Hall
Gibson, H. B. (1980), Hans Eysenck: the Man and his Work. London, England: Peter Owen
Goldsmith, A., Israel, M. & Daly, K. (2003), Crime and Justice: An Australian Textbook in Criminology. Pyrmont, NSW: Lawbook Company
Hollin, C.R. (1992), Criminal Behaviour: A Psychological Approach to Explanation and Prevention. London, England: The Falmer Press
Holman, J. E. & Quinn, J. F. (1992), Criminology: Applying Theory. St Paul, USA: West Publishing Company
Kristal, L. (1979), Understanding Psychology. Melbourne, Australia: Thomas Nelson
Link, R. & Mealey, L. (1992), The Sociobiology of Sociopathy: An Integrated Evolutionary Model. Paper, presented at Biology of Morality Conference, Bethel College, St. Paul, MN, USA
Raine, A. (1993), The Psychopathology of Crime: Criminal Behaviour as a Clinical Disorder. San Diego, USA: Academic Press
Vaughan, G. M., & Hogg, M. A. (2002), Introduction to Social Psychology. Sydney, Australia: Prentice Hall
Zimbardo, P. (1979). Psychology and Life. Illinois, USA, Scott, Foresman & Company
