The Science Of Guessing

Jonah Lehrer reports on a new study that appears to prove "psi" - instances of telepathy, clairvoyance or psychokinesis. But Lehrer reminds us it's been done before:

Consider the story of Adam Linzmayer. In the spring of 1931, Linzmayer, an undergraduate at Duke University, began participating in an experimental test of extra-sensory perception, or ESP. The study was led by the psychologist Joseph Banks Rhine and revolved around the Zener deck, a special set of cards featuring five different symbols. The test itself is straightforward: A card is drawn from the deck and the subject is asked to guess the symbol. While most of Rhine’s subjects performed in the neighborhood of random chance – they guessed about 20 percent of the cards correctly – Linzmayer averaged nearly fifty percent during his initial sessions. Furthermore, these “guesses” led to several uncanny streaks, such as when he correctly guessed nine cards in a row. The odds of this happening by chance are about one in two million. Linzmayer did it three times.

In a short time, Linzmayer lost his abilities, and performed only slightly higher than average. What makes the new study by Daryl Bem so important is "Bem’s attempt to create rigorous, well-controlled tests of psi that can be replicated by independent investigators."