Hans Eysenck Theory of Personality and Controversial Views

This article summarizes Hans Eysenck's main psychological views and his significant contributions to the understanding of personality, intelligence, and psychopathology.

Yelnur Shildibekov, PhD
Updated on: February 20, 2024
Reviewed by:
Alexander Tokarev, PhD

Hans Jürgen Eysenck (1916 – 1997) was a prominent psychologist and one of the most influential figures in the field of psychology and intelligence research. Born in Berlin, Germany, Eysenck spent his professional career in Great Britain, where he authored over 80 books and published countless articles, cementing his reputation as one of the most prolific psychologists of his time.

Hans Eysenck books, such as "The Structure of Human Personality" and "Personality and Individual Differences," became widely acclaimed in the field. His work has left a significant mark on the understanding of human behavior, the nature of personality traits, and what personality psychology really is. Throughout his career, he challenged prevailing theories, ignited controversies, and significantly advanced the field of psychology.

The PEN Model of Personality

Hans Eysenck theory of personality: the PEN model was one of his most important contributions to the field of psychology (Eysenck & Eysenck, 1975, 1985). This model proposed that three dimensions (fundamental personality traits): Psychoticism, Extraversion, and Neuroticism account for individual differences in behavior and susceptibility to mental illness.

Eysenck argued that these traits were biologically and genetically influenced, and relatively stable over time. Hans Eysenck personality test was based on the PEN model, and measured respondents’ levels on each of the three traits (also referred to as personality factors or personality dimensions). Importantly, these traits are measured on a continuum, ranging from low to high.

Extraversion-Introversion is the continuum with extraverts being on one end of the spectrum and Introverted individuals on the other. While extraverted individuals are sociable and outgoing, their counterparts scoring high in introversion are less socially active and more pessimistic.

Similarly, the Neuroticism dimensions has its own extremes: stable on one end and unstable on the other. Unlike the othertwo dimensions above, Psychoticism doesn’t have an opposite or inverse extreme in the PEN model.

Biological Basis of Personality

According to Eysenck (1967, 1975), the differences in personality traits were rooted in genetic and biological factors. He argued that variations in physiological processes, such as the reticular activating system and cortical arousal, contribute to individual differences in extraversion and neuroticism.

For example, Eysenck posed that the contrast between extraversion and introversion is linked to the balance of "inhibition" and "excitation" within the brain.Eysenck's emphasis on the biological basis of personality challenged the prevailing psychoanalytic and behaviorist perspectives at the time.

Intelligence and Individual Differences

Eysenck's research on intelligence focused on the study of individual differences and the heritability of intelligence. He proposed that intelligence had a strong genetic component and that environmental factors played a smaller role. Eysenck (1992a) challenged the prevailing view that intelligence was a single, unitary construct and instead suggested that there were multiple components, such as fluid intelligence (your ability to process new information, learn, and solve problems) and crystallized (your stored knowledge, accumulated over the years) intelligence.

Controversial Views on Psychotherapy

Eysenck's views on the effectiveness of psychotherapy stirred controversy within the field. He argued that the therapeutic benefits of traditional psychoanalysis and other forms of talk therapy were limited, and that many psychological disorders could be resolved without extensive therapy (Eysenck, 1997a, 1998a). Eysenck's stance sparked debates and led to discussions on the efficacy of different therapeutic approaches.

The "Criminal Personality" Theory

Eysenck explored the relationship between personality traits and criminal behavior. He proposed that individuals high in Psychoticism were more prone to engage in criminal activities due to their innate predisposition (Eysenck & Eysenck, 1977).Their personality types reflect neurotic temperament, and lack of empathy and emotional stability.Eysenck's theory of the "criminal personality" ignited debates on the interplay between genetics, personality, and antisocial behavior (Eysenck, 1994).

Hans Eysenck – Contributions to Psychopathology

Eysenck (1991) made significant contributions to the understanding of psychopathology, and shed light on the etiology of mental illnesses. He examined the relationships between personality traits and mental disorders, suggesting that certain traits, such as neuroticism and extraversion, were linked to specific psychiatric conditions.

Neuroticism: Eysenck (1992b) suggested that individuals high in neuroticism are more vulnerable to developing anxiety disorders, such as generalized anxiety disorder, phobias, and panic disorder. He posited that their heightened emotional reactivity and tendency towards negative affect make them more prone to experiencing excessive worry, fear, and stress.

Extroversion: Eysenck (1997b) proposed that individuals with high levels of extraversion are more susceptible to certain psychiatric conditions, including substance abuse disorders and behavioral addictions. He suggested that their tendency to seek external stimulation and engage in impulsive behavior may contribute to a higher risk of developing addictive behaviors.

Advocacy for Scientific Rigor

Throughout his career, Eysenck (1976, 1998b) advocated for scientific integrity and evidence-based approaches when conducting experiments and developing theories. He was critical of pseudoscience and unfounded psychotherapeutic practices.

Eysenck emphasized the importance of employing empirical research and rigorous methodology, such as experimental designs, control groups, and statistical analysis, to ensure the reliability and validity of research findings.


Hans Eysenck's contributions to psychology were both influential and controversial. His development of the PEN model of personality, emphasis on the biological basis of personality and intelligence, and his exploration of psychopathology left a lasting impact on the field. Although his views were met with criticism, Eysenck's commitment to scientific rigor and his willingness to challenge prevailing theories contributed significantly to the advancement of psychology as a scientific discipline.