The memory is a marvelous machine, filled with millions of independent little motors, each operating at its own speed and with its own purpose, but always connected to the Master Memory, the central computer. However, when one of those tiny motors is "unhooked" and allowed to "float free" it's possible to "trick" the Master Memory into "seeing" something that really doesn't, or didn't, exist.
Let me give you an example:
A subject, a former child star in the early days of television, was asked to act out a scene from his childhood, one in which he was convinced by an older friend to hand over all his money because the money was no longer "any good." As he lost himself deeper and deeper into the virtual experience the subject was once again persuaded by an older friend, played this time by a member of the clinic staff, to turn over all his old, "bad money." It worked!