From Tom Nicoli- World Hypnotism Day Committee: In 1998 Henry Szechtman of McMaster University in Ontario and his co-workers used PET to image the brain activity of hypnotized subjects who were invited to imagine a scenario in which they were listening to someone speaking to them, and who then actually experienced a scenario in which they were listening to someone speaking to them. The researchers noted that the act of imagining a sound, called hallucinating a sound, was experienced exactly the same as real hearing, both being experienced as coming from an external source.