a psychological theory developed by the American psychologist Frederick Herzberg in 1959. According to this theory, employee satisfaction and productivity are influenced by hygienic (see Hygienic Factors in Chapter 2.10: Key Psychological Concepts in Work Psychology) and motivational factors (see Motivational Factors in Chapter 2.10: Key Psychological Concepts in Work Psychology). The theory is based on the results of Herzberg’s study among 200 engineers and accountants of an industrial enterprise: participants were asked what brings them satisfaction from work, and what, on the contrary, causes dissatisfaction.