2.2 Evidence for Eysenck’s theory

Over the years, Eysenck’s theory of personality has received support from some psychologists, but has also received criticisms from others. Eysenck’s theory has been praised for combining the biological (arousal from the nervous system) and social (learning throughout childhood) elements to try and understand why people’s personalities differ, and why some people may commit criminal acts. However, it has also been criticised that there is little evidence that extraverts are more difficult to condition than introverts (Gross, 1996). This is an important aspect of the theory as it points to the biological basis for personality; however, if there is no research evidence to support it, then it weakens the theory that extraverts do not learn to develop a conscience through conditioning.

A number of studies have used Eysenck’s personality questionnaires to determine whether there really is a difference between those who act in antisocial or deviant ways, compared to those who do not. Center and Kemp (2002) compared the results of 60 studies with children and adolescents who were grouped as exhibiting ‘antisocial behaviour’ or ‘normal behaviour’, and were asked to complete an EPQ. When all the results were compared, they found that those who were labelled as exhibiting antisocial behaviour were more likely to score highly on the P scale compared to those who were labelled as normal. Those who were labelled as exhibiting antisocial behaviour were also more likely to have a low L score, giving further support to the theory that those who exhibit antisocial behaviour do not think about whether their actions are perceived as socially desirable. However, there were few differences between groups on the E and N scales, which do not support Eysenck’s theory.

There are several studies that have used adult participants to determine whether offenders in prisons differ in their personality according to Eysenck’s dimensions, as compared to non-offenders. Bourke et al. (2013) surveyed prisoners and found that those who were re-offenders (who have offended more than once) scored more highly on the P scale and were lower on the E and N scale compared to those who were first-time offenders. Boduszek et al. (2013) found that violent offenders scored more highly on the P scale. These studies seem to suggest there is some evidence that offenders can score differently to non-offenders on Eysenck’s personality questionnaire; however, offenders are more likely to score highly on the P scale and either no differently or even lower than ‘normal’ participants on the E or N scales.