American psychologist of Hungarian origin, known for his research on happiness, creativity, and subjective well-being. He is best known for his idea of “flow,” a special state that he studied for several decades. The state of flow can be considered the optimal state of intrinsic motivation, in which a person is fully involved in what he or she is doing (see Flow State (Autotelic Experience) in Chapter 1.10 Key Psychological Concepts in Positive Psychology).