Polish psychologist known for his research in differential psychology, personality psychology, and social psychology. He developed the regulatory theory of temperament, based on I. P. Pavlov’s theory of nervous system types, and created the Strelau Questionnaire method for diagnosing temperament. Strelau made significant contributions to understanding the genetic basis of personality and the relationship between temperament and stress response and health. He was a professor at the University of Warsaw, actively participated in the international psychological community and headed a number of scientific organizations.