Normally, Perception depends on the stimulation of sensory receptors by various kinds of energy. Perceptions independent of sensory stimulations are called extrasensory perceptions (ESP). The field that studies ESP is called parapsychology (Para means ‘besides’). The name itself indicates its failure to gain widespread acceptance within mainstream of psychology. Surveys reveal that a considerable percentage of population believe in ESPs. Moreover, leading Journals in psychology, philosophy and medicine periodically publish articles on paranormal abilities.
In 1971 the members of the ‘Grateful Dead’ rock band had their audiences try to transmit mental images of slides to a person asleep in a dream laboratory miles away. When the sleeper awake he described the content of his dreams. Independent judges rated his dream reports as more similar to the content of the slides than were the dream reports of another person who had not been designated to receive the images. It was reported as a successful demonstration of mental ‘telepathy’, the alleged ability to perceive the thoughts of others.
Clairvoyance is another famous ESP, which is the alleged ability to perceive objects of events without any sensory contact with them. One can be considered clairvoyant if he can identify the contents of a wooden box without opening it.
Precognition is the alleged ability to perceive events in the future. Predicting the next spin of the roulette wheel would be an example, which is one of the most common ways to predict precognitive ability.
Psychokinesis, the ability to control objects with mind alone, is also closely allied to ESP.