The Skeptics' Guide to the Universe: How to Know What's Really Real in a World Increasingly Full of Fake

by Steven Novella

Bem took standard psychological experiments and simply reversed their order. For example, he tested subjects’ ability to recall words and then let them practice with a set of words. He claims that words were easier to recall if they were studied afterward—so the effect of studying would have had to travel back in time to influence performance. ESP proponents were thrilled. Bem’s studies followed rigorous scientific protocols, were published in a peer-reviewed journal, and showed impressive statistical significance. Skeptics were not impressed—reversing the arrow of time is as close to impossible as you get in science, and at the very least it is an extraordinary claim. It’s much more likely that Bem simply made an error than that he overturned a fundamental scientific principle. The psychological and wider scientific communities, however, were worried. Bem followed all the rules, and yet his results could not be true. That implies there might be something wrong with the rules—with science itself. Everyone hoped that the conflict would be resolved with replications, which are the ultimate test of a scientific finding. If the effect is real, then anyone can find it. Most attempts at replicating Bem’s studies (which, to his credit, he made easy by providing documentation for all of his methods) were negative. However, a few ESP proponents were able to replicate his results. In the end, nothing was resolved—each side had its replications to point to: ESP proponents argued that...