Psychic abilities fail their most crucial test

The big problem with mental powers is you can never prove they exist. They never seem to be repeatable under experimental conditions, like other sorts of phenomena. Until recently — when a researcher named Daryl Bem claimed he'd done a study that indicated that people did indeed have some kind of precognition.

Bem urged other scientists to try the test themselves, so they could reproduce his results. They did, and his results proved unreplicable. Forgive the joke, but... he didn't see that coming.

In 2011, blogs lit up when Journal of Personality and Social Psychology published a study whose author, Daryl Bem, had put forward as being indicative of humans having psychic ability. The study consisted of a series of tests for precognitive ability.

The most infamous of the tests was the erotic picture test. The subjects were told that they would soon see two curtains displayed on a computer screen. 'Behind' one would be a picture. Behind the other would be a plain wall. They were to pick which curtain they felt hid a picture. The students were warned, as part of the disclaimer, that some pictures would show couples in explicit consensual sex acts, and told that if they objected to seeing such pictures they should not participate in the study.

The scientists believed that the subjects would be better at picking the right curtain, provided the curtain had a pleasingly erotic picture behind it. They found that this was the case — at least to a limited extent. Regular pictures were picked out 49.8 percent of the time. Erotic pictures were picked 53.1 percent of the time. This was a minor, but interesting bump in the data. Researchers felt they were on the right track, even when they had an early failure. Women picked out erotic pictures more unerringly than they did neutral pictures, while men didn't respond to them. This apparent female ability seemed to even out when the researchers looked for images that more men would find erotic. (They also introduced a feature in which women could choose to see only women-women pairings while men could choose the option of seeing man-man pairings.)

Psychic abilities fail their most crucial test


Bem's most dramatic test of precognition was the eighth and ninth experiment in the study. Subjects were given a list of words to memorize. There were forty-eight words split up into four categories. The words in each category were grouped together. After they were given the words, the subjects were asked to write down as many of them as they could remember. They were then given practice exercises on a subset of those words.

The idea was that they would remember more words in the subset that they'd practiced, even if the practice was done after they had finished the test. In each test, they did remember more of the practice words, though the practice had come after. The next experiment allowed them to practice the entire procedure all over again — after they had completed the first experiment - but only with the words that they had gotten to practice the first time. So instead of seeing the entire list of forty-eight words again, they saw a list of twenty-four. In this case, the subjects did almost twice as well at remembering the practice words (before they had any practice with them) as they did in the previous test.

The experiments ran in a series, slightly varied, testing a thousand different subjects. Although results varied, too, the overall evidence was for a slight precognitive ability allowing people to pick out the porn 0.21 percent of the time more than they could pick out the regular pictures — the average across all the experiments.

There were criticisms levied at the test. For example the practice words were checked, even ones that were close in spelling to the practice words were counted. Bem wrote to a blog critiquing this aspect of the test, saying that the spelling adjustments were not significant. For example, 'potatoe' would be corrected to 'potato' and counted as a hit.

There were also some counter-intuitive responses within the test itself. For example, in the erotic picture experiment, people chose erotic images more, and the experiment was specifically adjusted to show pictures that would appeal to them erotically. Therefore, people would psychically choose the pictures they 'liked.' However, some experiments showed that people, overall, would choose positive images 49.4 percent of the time, while they chose negative images 51.3 percent of the time, reversing the results of the experiment.

And so, it is not very surprising that on March 14, Stuart Ritchie of the University of Edinburgh published in PLoS ONE, the open-access journal, his own attempts at replicating the experiments. The testing was done with the full cooperation and support of Bem. In fact, since he believed a skeptical interviewer might make participants too wary and bias the experiment, he provided the programs that Edinburgh lab used to test the new batch of subjects. Although he repeated the celebrated word-memory experiment, which had the most promising findings, three times over, Ritchie found no statistically significant results.

Overall, in fact, it seemed that slightly fewer 'practiced' words were remembered than unpracticed words. Ritchie's study sought to replicate Bem's in every way, including the way the tests were scored. The only variable, acknowledged by Ritchie, was that his experiments took place after Bem's, and so the people going in to the study might have already heard of the experiments. This means they could have attempted memorization strategies that skewed the results, or simply felt more pressure to 'be psychic' or to disprove the idea of psychic phenomenon. Still, it appears that whatever small measure of psychic ability was measured at Cornell, where Daryl Bem worked, was dispersed by the time it reached Scotland.

Still, it's pleasant to see a 'precognitive' test laid out with precision, and to see the conductor of the experiment encourage others to test the results. What fun it would have been if they had been replicated.

Top Image: DC

Sign Image: Robbi Baba

Via Daryl Bem's Home Page, Richard Wiseman, Wired, and PLoS ONE.