In the 1930s Harry Price (director of the National Laboratory of Psychical Research) had investigated the medium Helen Duncan and had her perform a number of test séances. She was suspected of swallowing cheesecloth which was then regurgitated as "ectoplasm".[151] Price had proven through analysis of a sample of ectoplasm produced by Duncan, that it was made of cheesecloth.[152] Helen Duncan would also use a doll made of a painted papier-mâché mask draped in an old sheet which she pretended to her sitters was a spirit.[153] The photographs taken by Thomas Glendenning Hamilton in the 1930s of ectoplasm reveal the substance to be made of tissue paper and magazine cut-outs of people. The famous photograph taken by Hamilton of the medium Mary Ann Marshall depicts tissue paper with a cut out of Arthur Conan Doyle's head from a newspaper. Skeptics have suspected that Hamilton may have been behind the hoax.[154] 

It depends how you became a psychic medium; if you had a mentor, they will probably want to keep an eye over you for a while, just till you feel comfortable on your own. Even if you've come to this realization on your own, it can be helpful to get advice and guidance from an experiences psychic. In some cases, your clients might only trust you if you are known to have been mentored or guided by an experienced and known psychic.

Mediumship became quite popular in the 19th-century United States and the United Kingdom after the rise of Spiritualism as a religious movement. Modern Spiritualism is said to date from practices and lectures of the Fox sisters in New York State in 1848. The trance mediums Paschal Beverly Randolph and Emma Hardinge Britten were among the most celebrated lecturers and authors on the subject in the mid-19th century. Allan Kardec coined the term Spiritism around 1860.[12] Kardec claimed that conversations with spirits by selected mediums were the basis of his The Spirits' Book and later, his five-book collection, Spiritist Codification. 

Modern spiritualists and psychics keep detailed files on their victims. As might be expected, these files can be very valuable and are often passed on from one medium or psychic to another when one retires or dies. Even if a psychic doesn't use a private detective or have immediate access to driver's license records and such, there is still a very powerful technique that will allow the psychic to convince people that the psychic knows all about them, their problems, and their deep personal secrets, fears, and desires. The technique is called cold reading and is probably as old as charlatanism itself... If John Edward (or any of the other self-proclaimed speakers with the dead) really could communicate with the dead, it would be a trivial matter to prove it. All that would be necessary would be for him to contact any of the thousands of missing persons who are presumed dead—famous (e.g., Jimmy Hoffa, Judge Crater) or otherwise—and correctly report where the body is. Of course, this is never done. All we get, instead, are platitudes to the effect that Aunt Millie, who liked green plates, is happy on the other side.[195]
According to James Randi, a skeptic who has debunked many claims of psychic ability and uncovered fraudulent practices,[205] mediums who do cold readings "fish, suggest possibilities, make educated guesses and give options." Randi has a standing offer of $1 million US dollars for anyone who can demonstrate psychic ability under controlled conditions. Most prominent psychics and mediums have not taken up his offer.[206]
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]
Mina Crandon claimed to materialize a "spirit hand", but when examined by biologists the hand was discovered to be made from a piece of carved animal liver.[146] The German apport medium Heinrich Melzer was discovered to be a fraud in 1926. In a séance psychical researchers found that Melzer had small stones attached to the back of his ears by flesh coloured tape.[147] Psychical researchers who investigated the mediumship of Maria Silbert revealed that she used her feet and toes to move objects in the séance room.[148]
In 1910 at a séance in Grenoble, France the apport medium Charles Bailey produced two live birds in the séance room. Bailey was unaware that the dealer he had bought the birds from was present in the séance and he was exposed as a fraud.[114] The psychical researcher Eric Dingwall observed the medium Bert Reese in New York and claimed to have discovered his billet reading tricks.[115] The most detailed account at exposing his tricks (with diagrams) was by the magician Theodore Annemann.[116]
Mediumship became quite popular in the 19th-century United States and the United Kingdom after the rise of Spiritualism as a religious movement. Modern Spiritualism is said to date from practices and lectures of the Fox sisters in New York State in 1848. The trance mediums Paschal Beverly Randolph and Emma Hardinge Britten were among the most celebrated lecturers and authors on the subject in the mid-19th century. Allan Kardec coined the term Spiritism around 1860.[12] Kardec claimed that conversations with spirits by selected mediums were the basis of his The Spirits' Book and later, his five-book collection, Spiritist Codification.
^ "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". Dictionary.com. Retrieved 23 March 2007.