Age Regression
Age regression is a technique that is used in many schools of psychotherapy, most significantly hypnotherapy. This technique is used (either through hypnosis, relaxation techniques or Freudian "free association") to shift focus from the present as a means of exploring past events and memories.
Age regression also attempts to find behavior triggers, repressed memories, and other information that is not readily available to the conscious mind. This technique, however, is not infallible, in that it can also cause clients to exhibit "false" or "planted" memories that they believe to be real but are not. Controversially, this technique (usually by hypnosis) is also used by some practitioners as a means of accessing "past-life" memories as evidence of reincarnation. More research data is needed in order to fully understand this technique and gauge its effectiveness and reliability.