Experimental approach
 
Participant of a Ganzfeld Experiment which proponents say may show evidence of telepathy.Main article: Parapsychology
Experimental investigation of the paranormal is largely conducted in the multidisciplinary field of parapsychology. Although parapsychology has its roots in earlier research, it began using the experimental approach in the 1930s under the direction of J. B. Rhine (1895 �1980).[4] Rhine popularized the now famous methodology of using card-guessing and dice-rolling experiments in a laboratory in the hopes of finding a statistical validation of extra-sensory perception.[4]

In 1957, the Parapsychological Association was formed as the preeminent society for parapsychologists. In 1969, they became affiliated with the American Association for the Advancement of Science. That affiliation, along with a general openness to psychic and occult phenomena in the 1970s, led to a decade of increased parapsychological research.[4] During this time, other notable organizations were also formed, including the Academy of Parapsychology and Medicine (1970), the Institute of Parascience (1971), the Academy of Religion and Psychical Research, the Institute for Noetic Sciences (1973), and the International Kirlian Research Association (1975). Each of these groups performed experiments on paranormal subjects to varying degrees. Parapsychological work was also conducted at the Stanford Research Institute during this time.[4]

With the increase in parapsychological investigation, there came an increase in opposition to both the findings of parapsychologists and the granting of any formal recognition of the field. Criticisms of the field were focused in the founding of the Committee for the Scientific Investigation of Claims of the Paranormal (1976), now called the Committee for Skeptical Inquiry, and its periodical, Skeptical Inquirer.[4]

As astronomer Carl Sagan put it, "extraordinary claims require extraordinary evidence"[5], and experimental research into the paranormal continues today, though it has waned considerably since the 1970s.[6] One such experiment is called the Ganzfeld Experiment. The purpose of the Ganzfeld Experiment, like other parapsychological experiments, is to test for statistical anomalies that might suggest the existence of psi, a process indicating psychic phenomena.[7] In the Ganzfeld Experiment, a subject (receiver) is asked to access through psychic means some target. The target is typically a picture or video clip selected randomly from a large pool, which is then viewed in a remote location by another subject (sender). Ganzfeld experiments use audio and visual sensory deprivation to remove any kind of external stimulus that may interfere with the testing or corrupt the test by providing cues to correct targets. A 'hit' refers to a correctly identified target. The expected hit ratio of such a trial is 1 in 4, or 25%.[7] Deviations from this expected ratio might be seen as evidence for psi, although such conclusions are often disputed.[8] To date there have been no experimental results that have gained wide acceptance in the scientific community as valid evidence of paranormal phenomena. [6]