Freud's Psychosexual and Psychodynamic Theory
Freud graduated from medical school, planed his career in medical practice, and worked at the Vienna General Hospital to become a "recognized expert at diagnosing various types of brain damage" Hergenhahn, 2009, p. 519). His knowledge and experience in medical science, physiology, and human biology had influenced his work in originating the psychosexual development theory. This theory classified human development in five stages, - oral stage, anal stage, phallic stage, latency stage, and genital stage. These stages reflect the physiological and biological development of human life. For instance, the oral stage indicates human's initial biological needs for food, and the genital stage reflects sexual maturity from philological and biological perspective.
In his psychodynamic theory, Freud introduced three aspects of human mind, - id, ego, and superego in order to explain and differentiate among the conscious, the preconscious, and the unconscious (Hergenhahn, 2009). This theory revealed Freud's dualism view of the mind-body relationship because it acknowledges the existence of mind and consciousness along with the physical body of human beings. Freud's theories address both biological and mental mechanisms of human life. His theories impelled the expansion of psychology’s domain to studies of personality (Hergenhahn, 2009).
Hergenhahn, B. R. (2009). An introduction to the history of psychology (6th ed.). Belmont, CA: Wadsworth.