Hans Eysenck was a 20th century psychologist who studied a wide variety of psychological phenomena. He is best known for his work in the fields of intelligence and personality.

Personal and Professional Life

Hans Eysenck was born on March 4, 1916 in Berlin. His mother was an actress, and his father was a nightclub entertainer. With the rise of Nazi power in Germany, Eysenck moved to England in 1934 to attend University College in London. He received his PhD in 1940 while working at the college in the psychology department.

In 1955, Eysenck took a position at the Institute of Psychiatry at King’s College as a professor of psychology. He held that position until 1983 and published much of his work during that time. He focused his attention on intelligence and personality and helped launch the psychological journal Personality and Individual Differences.

Eysenck was a prolific writer and he wrote thousands of articles and nearly 100 books. At the time of his death in 1997, Eysenck held the distinction of being the most-cited psychologist in scientific journals. Michael Eysenck, Eysenck's son from his first marriage to Margaret Davies, is a well-known psychology professor. Eysenck was married a second time, to Sybil Rostal, with whom he had three sons and a daughter.

Contribution to Psychology

Eysenck's primary research interest was in the field of personality. He developed the concept of neuroticism, arguing that it was a biological form of emotional instability. He frequently argued that much of personality is genetically determined and published several papers on this topic.

He argued against psychoanalysis, claiming that it was unscientific. Instead, he favored a behavioral approach to therapy. His theory of personality compares two central factors, extraversion (E) and neuroticism (N), from which four basic personality types flow. His personality types are based on Hippocrates's personality formulation:

  • High N, High E results in a choleric personality—an assertive, leader-like person.
  • High N, Low E results in a melancholic personality—a cautious and introverted type.
  • Low N, High E results in a sanguine personality—the sociable and charismatic type.
  • Low N, Low E results in a phlegmatic personality—a consistent, calm person.


Eysenck held controversial views on the nature of intelligence, arguing that intelligence was at least partially genetic and that different racial groups had different levels of intelligence. These views remained controversial for his entire life, and he was once punched in the nose by a protester while giving a lecture. Eysenck did not shy away from controversy, and several interviews with him were published in the far-right press, leading to claims of racism and bigotry. He also published a piece in Penthouse.

Eysenck responded to many of his critics by arguing that there is a distinction between biological equality and equality of treatment under the law. The former, he emphasized, was impossible, while the latter was an important goal.

He worked on behalf of tobacco companies to conduct research on the effects of smoking. When asked about the ethics of this practice, he argued that what mattered was that the research was done correctly, not that the research was funded by the right, or wrong, group.