Hans Eysenck

Hans Jurgen Eysenck (1916-1997) was a German-born British psychologist whose theories of personality, intelligence, and behavior therapy made him among the most cited and most controversial psychologists of the twentieth century. Born in Berlin to the actor parents Eduard Anton Eysenck and Ruth Werner, he left Germany in 1934 in opposition to the new regime, completing his secondary education in France and his undergraduate and doctoral degrees at University College London under Cyril Burt.

Wartime work at the Mill Hill Emergency Hospital and the Maudsley Hospital led to his 1950 appointment as professor of psychology at the new Institute of Psychiatry at the University of London, a post he held until retirement in 1983. He built the institute's psychology department into a center of behavior therapy and personality research and supervised more than a hundred doctoral students.

His personality model, set out in Dimensions of Personality (1947) and refined in later books, described individual differences along the orthogonal axes of extraversion-introversion, neuroticism, and, from the 1970s, psychoticism, supported by the Eysenck Personality Questionnaire. His 1952 paper The Effects of Psychotherapy challenged the evidence base for then-dominant psychotherapeutic methods and helped open the way to behavior therapy.

His writings on intelligence, race, and the heritability of mental traits, including Race, Intelligence and Education (1971), drew sustained academic and public criticism. A 2019 review by King's College London concluded that twenty-six of his collaborative papers, mainly with Ronald Grossarth-Maticek on personality and disease, were "unsafe."

The given name Hans is a German short form of Johannes, from Hebrew Yochanan, meaning "Yahweh is gracious." He carried it through a career that combined prolific output with persistent dispute.