The Survival of the Fittists
Understanding the role of replication in research is crucial for the interpretation of scientific advances
ESP in North Carolina
A wonderful example of this effect originated in the 1930s at Duke University. J. B. Rhine, a botanist turned parapsychologist, designed studies that he hoped would discover people with extrasensory perception (ESP). He thought he had found one in Adam Linzmayer, an economics undergraduate at Duke. In spring 1931, as a volunteer in one of Rhine’s experiments, Linzmayer performed far better than chance suggested he should. In subsequent experiments his performance retreated back to chance. Rather than dismiss the initial finding, Rhine concluded that Linzmayer’s “extra sensory perception has gone through a marked decline.” But Rhine kept searching for people with ESP talent until he encountered another experimental subject, Hubert Pearce, who had a remarkable run of successes before he too suffered the loss of his psychic gift. This spotty record did not deter the energetic Rhine. The University of Chicago researcher Harold Gulliksen wrote a scathing review of Rhine’s 1934 opus Extra-Sensory Perception, suggesting that although the statistical methods Rhine used were seriously flawed, he would not discuss them for fear that he would distract attention from the monumental errors in Rhine’s experimental design. (For example, if you looked carefully at the cards he used to test subjects, you could see an outline of their patterns from the reverse side. Such flaws are often overlooked by scientists inexperienced in magic. Stanford statistician and magician Persi Diaconis spent a fair amount of time debunking claims of ESP made by Uri Geller and others. Diaconis proposed that he was uniquely qualified for such a task; magicians couldn’t do it because they didn’t understand experimental design, and psychologists couldn’t do it because they didn’t know magic. His claim has subsequently been borne out by evidence.)
Rhine’s reaction to and interpretation of normal stochastic variation provides an object lesson in how humans, even scientists, allow what they want to be true to overwhelm objective good sense. Nobel Prize Laureate Daniel Kahneman spends the 500 pages of his recent book, Thinking, Fast and Slow, laying out how and why humans behave this way. It is left to scientists to remember this tendency as we do our work.