Erick Erickson worked with Sigmund Freud who developed psychoanalysis and the concepts of the id, ego, and superego. In regards to ego psychology Freud proposed that the ego created compromise between the drives of the superego and id by regulating impulses. Erickson later revised this concept to include his concepts of how society and culture effect behavior. He proposed that the internal forces of the id, ego, and super ego were not the only way we regulated our behavior and that external forces in our environment also have a determination in how our behavior is shaped. Erickson proposed that the id, ego, and superego were internal forces that pushed our behavior within the environment while the external environment provides resistance which regulated and shaped the reactions of the id, ego, and superego.