Psychical research

Psychical research is the historical investigation of alleged mental phenomena beyond ordinary sensory or physical explanation, including telepathy, clairvoyance, and mediumship.

Ganzfeld experiment: A sensory-reduction procedure used to test whether participants can receive information through alleged extrasensory perception. It became a controlled method for testing telepathy claims.
Spiritualism: A religious movement based on the belief that the living can communicate with the spirits of the dead. Its séances and claims prompted organized investigation of mediumship.
Eleanor Sidgwick: A British educator and psychical researcher who conducted investigations for the Society for Psychical Research. Her careful studies of mediums helped set standards for evidence in the field.
Clever Hans: A horse whose apparent ability to solve arithmetic problems was traced to responses to human cues. The case exposed the risk of unrecognized cues in tests of unusual abilities.
Parapsychology: A discipline that studies alleged phenomena such as telepathy, clairvoyance, and psychokinesis. It is the modern research field most directly continuous with psychical research.
Clever Hans effect: A phenomenon in which an apparent display of intelligence is produced by an observer's involuntary cues. It illustrates how subtle cues can mimic paranormal information transfer.
Society for Psychical Research: A British organization founded in 1882 to investigate alleged paranormal phenomena using systematic inquiry. It institutionalized the field and shaped its early research agenda.
Richard Hodgson: An Australian-born investigator who examined spiritualist mediums and exposed several cases of fraud. His investigations made deception a central concern in psychical research.
Scole Experiment: A series of séances conducted in England in the 1990s that participants presented as evidence of spirit communication. It became a modern controversy over observation, controls, and alleged physical phenomena.
Skepticism: A practice of withholding belief until claims receive adequate evidence and critical examination. Skeptical analysis challenges whether reported effects exceed ordinary explanations.

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