The psychical researchers Eric Dingwall and Harry Price re-published an anonymous work written by a former medium entitled Revelations of a Spirit Medium (1922) which exposed the tricks of mediumship and the fraudulent methods of producing "spirit hands". Originally all the copies of the book were bought up by spiritualists and deliberately destroyed. 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.
Illusionists, such as Joseph Rinn have staged 'fake' séances in which the sitters have claimed to have observed genuine supernatural phenomena. Albert Moll studied the psychology of séance sitters. 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." The psychologists Leonard Zusne and Warren Jones in their book Anomalistic Psychology: A Study of Magical Thinking (1989) wrote that spirits controls are the "products of the medium's own psychological dynamics."
In 1880 the American stage mentalist Washington Irving Bishop published a book revealing how mediums would use secret codes as the trick for their clairvoyant readings. The Seybert Commission was a group of faculty at the University of Pennsylvania who in 1884–1887 exposed fraudulent mediums such as Pierre L. O. A. Keeler and Henry Slade. The Fox sisters confessed to fraud in 1888. Margaret Fox revealed that she and her sister had produced the "spirit" rappings by cracking their toe joints.