In psychometry the psychic holds an object and obtains impressions of the person to whom the object belongs or who may have had contact with it. Like the crystal ball, or other scrying objects, the psychometric object becomes a tool that can stimulate the psychic skills. Every object has a psychic history and gives off emotional vibrations absorbed from people who have handeled it. The objects can also reflect past events as well as personalities as in the case of Gerald Croiset. In one series of experiments, Croiset was handed fossil fragments and he was able to accurately place in the correct period and time. Objects are strongly impregnated with vibrations of highly emotional events like disasters. Another psychic who held a piece of lava from a volcano shook with a feeling of terror and fear for over an hour after the experiment ended.
Psychometric experiments have also used the means to conceal the object to be read. In another of Croiset's experiments, he was given an opaque envelope to read containing a medieval manuscript. Croiset described an image of a pope, a knight and a monk. Even using a fragment of an object has shown to be as good as working with the whole. Psychic investigator William T. Sted handed psychometrists blank squares of paper that had been cut from letters written by famous people in which many were accurately identified.
William Roll of the Psychical Research Foundation believes objects made of animal or vegetable sources have a stronger property then those made of inorganic matter such as metal. In one of his experiments, psychics reacted more strongly to cardboard then to aluminum foil. William Roll also believes that every object is surrounded by an energy field and that events leave traces in this field. Psi fields are also created when people interact with each other or with objects and events. According to this "memory trace" theory, each object acts much like the human subconscious, storing strong impressions of people, events and surroundings associated with it.