Over centuries, organised perpetrator groups have observed and studied the way in which extreme childhood traumas, such as accidents, bereavement, war, natural disasters, repeated hospitalisations and surgeries, and (most commonly) child abuse (sexual, physical, and emotional) cause a child's mind to be split into compartments. Occult groups originally utilised this phenomenon to create alternative identities and what they believed to be “possession” by various spirits. In the twentieth century, probably beginning with the Nazis, other organised groups developed ways to harm children and deliberately structure their victims' minds in such a way that they would not remember what happened, or that if they began to remember they would disbelieve their own memories. Consequently, the memories of what has happened to a survivor are hidden within his or her inside parts.