Michael Shermer criticized mediums in Scientific American, saying, "mediums are unethical and dangerous: they prey on the emotions of the grieving. As grief counselors know, death is best faced head-on as a part of life." Shermer wrote that the human urge to seek connections between events that may form patterns meaningful for survival is a function of natural evolution, and called the alleged ability of mediums to talk to the dead "a well-known illusion of a meaningful pattern."
Spiritualists believe that phenomena produced by mediums (both mental and physical mediumship) are the result of external spirit agencies. The psychical researcher Thomson Jay Hudson in The Law of Psychic Phenomena (1892) and Théodore Flournoy in his book Spiritism and Psychology (1911) wrote that all kinds of mediumship could be explained by suggestion and telepathy from the medium and that there was no evidence for the spirit hypothesis. The idea of mediumship being explained by telepathy was later merged into the "super-ESP" hypothesis of mediumship which is currently advocated by some parapsychologists.
Humans have been fascinated with contacting the dead since the beginning of human existence. Cave paintings by indigenous Australians date back 28,000 years, some depicting skulls, bones, spirits and the afterlife. Other cave paintings in Indonesia date back a further 10,000 years. Mediumship gained popularity during the nineteenth century, when ouija boards were used by the upper classes as a source of entertainment. Investigations during this period revealed widespread fraud—with some practitioners employing techniques used by stage magicians—and the practice began to lose credibility. Fraud is still rife in the medium/psychic industry, with cases of deception and trickery being discovered to this day.