Psychoanalysis is a form of therapy based on psychoanalytic theory. This theory states that human behavior is controlled by unconscious forces such as instinct and that there is no such thing as free will. Many ideas found in the theory can be traced back to Sigmund Freud. Freud believed mental disorders are a result of repressed memories and emotions from childhood; psychoanalysis is designed to search for these hidden memories and emotions and bring them to the patient's attention. Techniques such as hypnosis are used to tap into the unconscious mind with the hopes that the source of the disturbance is found. Freud also believed dreams had hidden meanings, and often asked patients to record their dreams for analysis. Because of the lack of scientific evidence supporting most Freudian ideas, psychoanalysis is rarely used by clinical psychologists and has been replaced by more effective forms of therapy.