Quote from : Secret Weapons: How Two Sisters Were Brainwashed To Kill For Their Country Book

To the men and women who changed Cheryl Hersha's life, she was a continuation of the research that had first been conducted in the late nineteenth and early twentieth centuries by Dr. Morton Prince. He encountered a woman named Miss Beauchamp, a nursing student who was referred to the psychiatrist because of health problems. As he worked with her, Prince discovered that she had four separate personalities (dissociated ego states) that existed independently of one another within the same body. Though he tried, Dr. Prince never understood Miss Beauchamp, nor was he able to help her. When he died, his wife had the woman committed to an insane asylum for the rest of her life. However, Prince's careful documentation of Beauchamp's symptoms, actions and family history (extreme child abuse beginning before the age of seven) provided information needed to develop the techniques for contemporary, routinely successful treatment of what would be called Multiple Personality Disorder.