• Telepathy, or mind-to-mind communication--one person sending thoughts to another or perceiving another's thoughts.
• Clairvoyance, or perceiving remote events, such as sensing that a friend's house is on fire.
• Precognition, or perceiving future events, such as a political leader's death or a sporting event's outcome.

Closely linked with these are claims of psychokinesis, or "mind over matter," such as levitating a table or influencing the roll of a die.

Which supposed psychic ability does the sportscaster claim?

On stage, the "psychic," like a magician, controls what the audience sees and hears. In the laboratory, the experimenter controls what the psychic sees and hears. Consider one careful experiment conducted by Bruce Layton and Bill Turnbull (1975) at the University of North Carolina. Layton and Turnbull had a computer generate a randomized 100-item list of the digits 1, 2, 3, 4, and 5 for each of their 179 student participants. They gave each student such a list in a sealed envelope and asked the student to guess which number was in each of the 100 positions.

By chance, 1 guess in 5, or 20 guesses out of the 100, should be correct. When told beforehand that ESP was beneficial, subjects averaged 20.66 correct out of 100. When told that ESP was harmful, they averaged only 19.49 correct. The difference might seem insignificant--indeed, you would never notice so small an effect while observing an experiment. But a statistical analysis revealed that a difference that large among so many participants would seldom occur by chance. So Layton and Turnbull concluded that an ESP effect had occurred.

Bolstered by such experiments, believers in ESP accuse research psychologists of the same sort of skepticism that led eighteenth-century scientists to scoff at the idea that meteorites come from outer space. Novelist Arthur Koestler, who in 1983 left more than $700,000 to fund a British professorship in parapsychology, once complained that today's skeptical scientists resemble the Italian philosophers who refused to look at Jupiter's moons through Galileo's telescope--because they "knew" that such moons did not exist. Stubborn skepticism sometimes blinds people to surprising truth.