Extrasensory perception (ESP)

ESP is the acquisition of information from the external environment or from another mind other than through any known sensory channels. One hypothesis suggests this is perception of energy through some unexplained, spaceless function. Others point to biological harmony between sender and receiver (heartbeats, brainwaves); a relationship with electric and magnetic force fields; and cosmic static, or the interception of an intermediate third party. Some psychologists argue that, since sensory perception is not fully understood even in the case of the known channels, the term may overemphasize a difference between parapsychological phenomena and related events in orthodox areas of psychology. The term [psi]

is used for any phenomenon that might be termed extrasensory perception or psychokinesis.

Four basic forms of ESP are distinguished, although they may be closely interlinked: [telepathy]

, or thought transference; [clairvoyance]

, or seeing distant objects or events; [precognition]

, or prophecy; and [psychokinesis]

, or influencing physical events through mental operations.

The evidence for the existence of ESP is often persuasive, judged by scientific standards ordinarily applied in other areas of psychology. Reservations exist because: the phenomena are not as reproducible as in other disciplines; the phenomena require much firmer evidence than normal to justify such an implausible hypothesis; the effects claimed are ordinarily very slight; and statistical questions are raised concerning the manner in which the results of the large number of trials in each experiment are analyzed.