Freudian psychology is based on the work of Austrian neurologist Sigmund Freud (1856-1939). He is considered the father of psychoanalysis and is largely credited with establishing the field of talk therapy. Today, psychoanalytic and psychodynamic approaches to therapy are the modalities that draw most heavily on Freudian principles. Freud also developed influential theories about subjects such as the unconscious mind, the sources of psychopathology, the significance of dreams.