Hans Eysenck was a prominent psychologist known for his work in personality theory and psychometrics. He developed the Pen model of personality, which categorized individuals into extroversion, introversion, and later two additional dimensions: neuroticism and psychoticism. Eysenck believed that these traits were influenced by genetics and biology and argued that personality is largely stable throughout an individual's life. In addition to his theories on personality, Eysenck was also known for his controversial views on...