According to James Randi, a skeptic who has debunked many claims of psychic ability and uncovered fraudulent practices, 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.
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). Lambert who had studied Gustav Geley's files on the medium Eva Carrière discovered photographs depicting fraudulent ectoplasm taken by her companion Juliette Bisson. Various "materializations" were artificially attached to Eva's hair by wires. The discovery was never published by Geley. 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.