In the 1860s and 1870s, trance mediums were very popular. Spiritualism generally attracted female adherents, many who had strong interests in social justice. Many trance mediums delivered passionate speeches on abolitionism, temperance, and women's suffrage. Scholars have described Leonora Piper as one of the most famous trance mediums in the history of Spiritualism.
The Austrian medium Rudi Schneider was investigated in 1924 by the physicists Stefan Meyer and Karl Przibram. They caught Rudi freeing his arm in a series of séances. Rudi claimed he could levitate objects but according to Harry Price a photograph taken on April 28, 1932 showed that Rudi had managed to free his arm to move a handkerchief from the table. According to Warren Jay Vinton, Schneider was an expert at freeing himself from control in the séance room. Oliver Gatty and Theodore Besterman who tested Schneider concluded that in their tests there was "no good evidence that Rudi Schneider possesses supernormal powers."
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.