Hans Eysenck was a psychologist who developed a theory of personality consisting of three types: introversion/extraversion, stability/neuroticism, and impulse control/psychoticism. He believed these types were biologically based and could be measured using statistical analyses of personality data. Eysenck proposed that extraverts have weaker inhibitory processes, making them more stimulation-seeking, while introverts have stronger processes, causing them to prefer more solitary activities. He also advocated for behavior therapy techniques like systematic desensitization to treat neurotic behaviors and disorders.

1. 1916 - 1997