In contrast to Allport’s trait theory, Hans Eysenck argued that there are just 2 factors that define personality type; extroversion (E) and Neuroticism (N). These are largely genetically determined and fixed characteristics. Extroverts are sociable, lighthearted, and fun-loving, and Neurotic people – in Eysenck’s use of the term – are unstable, moody, and easily affected by their feelings.
Each dimension of personality varies along a continuum, ranging from extroverted to introverted, and neurotic to balanced. However, each person can be plotted according to his/her level of extraversion/extraversion, neuroticism/neuroticism, and so on. The similarities with the classical theory of humor are striking, which Eysenck acknowledged. Eysenck’s theory is sometimes described by psychologists as a type theory, but he disliked the concept of types, preferring to see personality as varying along a continuous scale.