spiritism or spiritualism, belief that the human personality continues to exist after death and can communicate with the living through the agency of a medium or psychic. The advocates of spiritism argue that death merely means a change of wavelength for those who die, and the medium is said to be able to receive radiations, frequencies, or vibrations that cannot be sensed by an ordinary person. Communication from the spirit world manifests itself in psychical phenomena (e.g., telepathy, clairvoyance, trance speaking, and apparitions) and in physical phenomena (e.g., levitation, automatic writing, and poltergeist and ectoplasmic activities). Ectoplasm is the mysterious visible substance in which the forces of the "other world" materialize. Closely related to the concept of the ectoplasm is the aura, a colored emanation that supposedly surrounds all individuals and that can be perceived by the medium. By noting variations in the hues of a person's aura, the medium is able to describe his personality, needs, and illnesses. The shriveling of the aura is considered a sign of an impending death. In what is known as solar plexus voice mediumship, a spirit appears to speak through a medium's body. Modern spiritism in the United States dates from the activities of the Fox sisters in 1848. Such notable figures as Andrew Jackson Davis, Daniel Dunglas Home, Helena Petrovna Blavatsky, and Arthur Conan Doyle later became widely known spiritualists. The Society for Psychical Research has carried on investigations with some phenomena, mainly in connection with telepathy and apparitions, in hopes of finding scientific explanations for various spiritualistic occurrences (see parapsychology).
See A. F. Schrenck von Notzing, Phenomena of Materialization (1920); Sir Arthur Conan Doyle, History of Spiritualism (1926); Sir Oliver Lodge, Phantom Walls (1930); S. E. White, The Unobstructed Universe (repr. 1959); G. K. Nelson, Spiritualism and Society (1969); S. Brown, The Heyday of Spiritualism (1970).