The exposures of fraudulent activity led to a rapid decline in ectoplasm and materialization séances.[202] 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. They instead use "mental mediumship" tactics like cold reading or gleaning information from sitters before hand (hot reading). Group readings also improve hits by making general statements with conviction, which will fit at least one person in the audience. Shows are carefully edited before airing to show only what appears to be hits and removing anything that does not reflect well on the medium.[203]
In the 1920s the British medium Charles Albert Beare duped the Spiritualist organization the Temple of Light into believing he had genuine mediumship powers. In 1931 Beare published a confession in the newspaper Daily Express. In the confession he stated "I have deceived hundreds of people…. I have been guilty of fraud and deception in spiritualistic practices by pretending that I was controlled by a spirit guide…. I am frankly and whole-heartedly sorry that I have allowed myself to deceive people."[124] Due to the exposure of William Hope and other fraudulent spiritualists, Arthur Conan Doyle in the 1920s led a mass resignation of eighty-four members of the Society for Psychical Research, as they believed the Society was opposed to spiritualism.[125]

In the late 19th century, the fraudulent methods of spirit photographers such as David Duguid and Edward Wyllie were revealed by psychical researchers.[95] Hereward Carrington documented various methods (with diagrams) how the medium would manipulate the plates before, during, and after the séance to produce spirit forms.[96] The ectoplasm materializations of the French medium Eva Carrière were exposed as fraudulent. The fake ectoplasm of Carrière was made of cut-out paper faces from newspapers and magazines on which fold marks could sometimes be seen from the photographs.[97] Cut out faces that she used included Woodrow Wilson, King Ferdinand of Bulgaria, French president Raymond Poincaré and the actress Mona Delza.[98]
^ "Glossary of Key Words Frequently Used in Parapsychology" Archived 2010-12-24 at the Wayback Machine, Parapsychological Association website. "Materialization: A phenomenon of physical mediumship in which living entities or inanimate objects are caused to take form, sometimes from ectoplasm." Retrieved January 24, 2006 "Medium – Definition". Retrieved 23 March 2007.