Psychologist Leshan is an expert in the field of psychology, specializing in the study of human behavior and mental processes. He is best known for his work on the EDA (Existential-Dynamic Approach) which is a psychotherapeutic approach that focuses on the individual's experience of life and how it affects their behavior. The EDA is based on the idea that individuals have the capacity to make choices and take responsibility for their lives. Leshan has written several books on the subject and has been featured in various media outlets.