Investigations on parasychology

Among the early achievements of the British group was the investigation of hypnotism , a field later claimed by medicine and psychology. The society also investigated phenomena produced at spiritualistic séances and the claims of spiritualism. Psi phenomena to be investigated were classified as either physical or mental. The physical effects, or PK, include the movement of physical objects or an influence upon material processes by the apparent direct action of mind over matter. The mental manifestations, or ESP, include telepathy, which is the direct transmission of messages, emotions, or other subjective states from one person to another without the use of any sensory channel of communication; clairvoyance, meaning direct responses to a physical object or event without any sensory contact; and precognition, or a noninferential response to a future event.

One of the first specific investigations in the field was the examination, by the British chemist and physicist Sir William Crookes, of the phenomena produced at séances held by the Scottish medium Daniel Dunglas Home. Home, a physical medium, generally used some type of lighting during his séances, and the validity of the paranormal phenomena he produced has never been successfully impugned. The contents of verbal utterances by mental mediums were also studied. Significant early research involved the American medium Leonore E. Piper, whose apparent psychical gifts were discovered by the American philosopher and psychologist William James. Other lines of investigation dealt with psychic experiences that seemed to occur spontaneously in everyday life, and involved the controlled testing of persons with apparently outstanding ESP abilities.

While the results of such experiments are regarded by some parapsychologists as having demonstrated the existence of some forms of psychic abilities the consensus of the scientific community is that psychic abilities have not been demonstrated to exist. Critics argue that methodological flaws may explain any apparent experimental successes