eysenck theory

Eysenck Theory of Personality Traits

Personality Psychology

An Introduction to the Eysenck Theory of Three Factors

Hans Eysenck (1916-1997) developed a very influential trait theory of personality, which has successful infiltrated the public mindset with regards to how we think about personality in day-to-day life.

Using factor analysis to devise his theory, Eysenck (1947, 1966) identified three factors of personality: extroversion, neuroticism and psychoticism.

Each of the Eysenck Theory factors is a bipolar dimension, meaning that each has a direct opposite:

  • Extroversion vs. Introversion
  • Neuroticism vs. Emotional Stability
  • Psychoticism vs. Self-Control (added to the model in 1966)

It is worth noting that Eysenck's use of the term 'psychoticism' differs from how most clinical psychologists would use the word. Eysenck is referring to anti-social behaviours, not a mental illness.

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Defining the Eysenck Theory Factors


'n. an orientation of one's interests and energies toward the outer world of people and things rather than the inner world of subjective experience. ... Extroverts are relatively more outgoing, gregarious, sociable, and openly expressive.'1

Adjectives associated with extroversion include: impulsive, optimistic, active, sociable, outgoing and talkative.


'n. orientation toward the internal private world of one's self and one's inner thoughts and feelings, rather than toward the outer world of people and things. ... Introverts are relatively more withdrawn, retiring, reserved, quiet, and deliberate; they may tend to mute or guard expression of positive affect, adopt more skeptical views or positions, and prefer to work independently.'

Adjectives associated with introversion include: reserved, unsociable, quiet, passive, careful, thoughtful and peaceful.

Neuroticism (unstable)

'characterized by a chronic level of emotional instability and proneness to psychological distress.'

Adjectives associated with neuroticism include: anxious, moody, touchy, restless and aggressive.

Emotionally Stable

Characterised by 'predictability and consistency in emotional reactions, with absence of rapid mood changes.'

Adjectives associated with emotional stability include: reliable, even-tempered, calm, leadership and carefree.


'n. a dimension of personality ... characterized by aggression, impulsivity, aloofness, and anti-social behavior, indicating a susceptibility to psychosis and psychopathic disorders.'

Adjectives associated with emotional stability include: impulsive, aggressive, anti-social and aloof.

Self Control

'n. the ability to be in command of one's behavior (overt, covert, emotional, or physical) and to restrain or inhibit one's impulses.'

Adjectives associated with self control include: restrained, calm, thoughtful and considerate.

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A Biological Basis of Personality

More than other trait theories, the Eysenck Theory of personality places a great deal of emphasis on the biological nature of personality (Eysenck, 19912).

For example, Eysenck attributes the introversion-extroversion dimension to be rooted in the biological requirements to achieve an optimal arousal level of the brain. Introverts have relatively high levels of cortical excitation, whereas extroverts demonstrate relatively low levels. Therefore, in order to achieve optimal stimulation, an extrovert must seek more external stimulation than an introvert. Conversely, an introvert avoids external stimulation in order to maintain their biologically-occurring optimal stimulation.

Support for the Eysenck Theory of Personality

Eysenck's three dimensions of personality have received considerable empirical support, not least from Eysenck's own laboratory. Most trait theorists accept the existence of Eysenck's three factors, as factor analyses conducted by a large number of researchers produce similar results - this suggests Eysenck's approach has strong internal validity, as the results are easily reproducible.

Eysenck's three factors have the highest validity of all proposed personality factors (Kline, 1993).

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  1. All Dictionary Definitions: APA Dictionary of Psychology
  2. Eysenck, H.J. (1991) Dimensions of personality: 16, 5, or 3? Criteria for a taxonomic paradigm. Personality and Individual Differences, 12, 773-790