Spiritualists classify types of mediumship into two main categories: "mental" and "physical":[10] During seances, mediums are said to go into trances, varying from light to deep, that permit spirits to control their minds.
According to (Wolffram, 2012) "[Moll] argued that the hypnotic atmosphere of the darkened séance room and the suggestive effect of the experimenters' social and scientific prestige could be used to explain why seemingly rational people vouchsafed occult phenomena.
[45]In a series of experiments holding fake séances, (Wiseman et al. 2003) paranormal believers and disbelievers were suggested by an actor that a table was levitating when, in fact, it remained stationary.
Oliver said "...when psychic abilities are presented as authentic, it emboldens a vast underworld of unscrupulous vultures, more than happy to make money by offering an open line to the afterlife, as well as many other bullshit services.
[58] While advocates of mediumship claim that their experiences are genuine, the Encyclopædia Britannica article on spiritualism notes in reference to a case in the 19th century that "...one by one, the Spiritualist mediums were discovered to be engaged in fraud, sometimes employing the techniques of stage magicians in their attempts to convince people of their clairvoyant powers."
"[59] At a séance in the house of the solicitor John Snaith Rymer in Ealing in July 1855, a sitter Frederick Merrifield observed that a "spirit-hand" was a false limb attached on the end of the medium Daniel Dunglas Home's arm.
[69] In 1875, he was caught pretending to be a spirit during a séance in Liverpool and was found "clothed in about two yards of stiffened muslin, wound round his head and hanging down as far as his thigh.
[83] In 1891 at a public séance with twenty sitters the medium Cecil Husk was caught leaning over a table pretending to be a spirit by covering his face with phosphor material.
[104] between 1908 and 1914 the Italian medium Francesco Carancini was investigated by psychical researchers and they discovered that he used phosphorus matches to produce "spirit lights" and with a freed hand would move objects in the séance room.
[116] According to the psychical researcher Harry Price "Her tricks were usually childish: long hairs attached to small objects in order to produce 'telekinetic movements'; the gradual substitution of one hand for two when being controlled by sitters; the production of 'phenomena' with a foot which had been surreptitiously removed from its shoe and so on.
[130] In 1923, the magician Carlos María de Heredia revealed how fake spirit hands could be made by using a rubber glove, paraffin and a jar of cold water.
[138] In 1925, Samuel Soal claimed to have taken part in a series of séances with the medium Blanche Cooper who contacted the spirit of a soldier Gordon Davis and revealed the house that he had lived in.
Researcher Melvin Harris who studied the case wrote that the information described in Garrett's séances were "either commonplace, easily absorbed bits and pieces, or plain gobblede-gook.
Evans was later discovered to be a fraud as a cord leading from a device in his hand has indicated that it was himself who triggered the flash-photograph and that all he had done was jump from his chair into the air and pretend he had levitated.
[153] According to the magician John Booth the stage mentalist David Devant managed to fool a number of people into believing he had genuine psychic ability who did not realize that his feats were magic tricks.
Birkeland turned on the lights during a séance, snatched her trumpets and discovered that the "spirit" noises were caused by chemical explosions induced by potassium and water and in other cases by lycopodium powder.
[156] In 1954, the psychical researcher Rudolf Lambert published a report revealing details about a case of fraud that was covered up by many early members of the Institute Metapsychique International (IMI).
Eugéne Osty (the director of the institute) and members Jean Meyer, Albert von Schrenck-Notzing and Charles Richet all knew about the fraudulent photographs but were firm believers in mediumship phenomena so demanded the scandal be kept secret.
[163] In 1970 two psychical researchers investigated the direct-voice medium Leslie Flint and found that all the "spirit" voices in his séance sounded exactly like himself and attributed his mediumship to "second-rate ventriloquism".
"[173] In 1992, Richard Wiseman analyzed the Feilding report of Eusapia Palladino and argued that she employed a secret accomplice that could enter the room by a fake door panel positioned near the séance cabinet.
[174] Massimo Polidoro and Gian Marco Rinaldi also analyzed the Feilding report but came to the conclusion no secret accomplice was needed as Palladino during the 1908 Naples séances could have produced the phenomena by using her foot.
[175] Colin Fry was exposed in 1992 when during a séance the lights were unexpectedly turned on and he was seen holding a spirit trumpet in the air, which the audience had been led to believe was being levitated by spiritual energy.
[176] In 1997, Massimo Polidoro and Luigi Garlaschelli produced wax-moulds directly from one's hand which were exactly the same copies as Gustav Geley obtained from Franek Kluski, which are kept at the Institute Metapsychique International.
Hyman criticizes Schwartz's decision to publish his results without gathering "evidence for their hypothesis that would meet generally accepted scientific criteria... they have lost credibility.
Schwartz claimed to have contacted the spirit of a 25-year-old man in the bathroom of his parents house and it is alleged he attempted to charge the family 3.5 million dollars for his mediumship services.
[192] Investigator Joe Nickell has written that modern self-proclaimed mediums like John Edward, Sylvia Browne, Rosemary Altea and James Van Praagh are avoiding the Victorian tradition of dark rooms, spirit handwriting and flying tambourines as these methods risk exposure.
"[194] According to James Randi, a skeptic who has debunked many claims of psychic ability and uncovered fraudulent practices,[195] mediums who do cold readings "fish, suggest possibilities, make educated guesses and give options."
[199] The article about this phenomenon in Encyclopædia Britannica places emphasis that "… one by one spiritual mediums were convicted of fraud, sometimes using the tricks borrowed from scenic "magicians" to convince their paranormal abilities".
In the article it is also noted that "… the opening of the wide ranging fraud happening on spiritualistic sessions caused serious damage to reputation of the movement of a Spiritualism and in the USA pushed it on the public periphery".
[201] As Jack Hitt reported in The New York Times: "Over the course of the reading, John comfortably laid down the specifics of Susanna Wilson’s life — he named “Andy” and amazingly knew him to be her twin.