Sunday, January 9, 2011

"Evidence" for precognition hurts the perception of psychology as a science

There is a a paper in press at the most prestigious journal in my field, Journal of Personality and Social Psychology, that claims to have found evidence of ESP.

In this paper, Daryl Bem, a well-known and well-respected psychologist at Cornell University, conducted 9 time-reversed versions of classic social psychology experiments. For example, one common way of testing for associations between sets of concepts is through priming, in which an picture is flashed very quickly on a computer screen, after which the participant must categorize a second object. People are usually faster at categorizing the second object when the two objects share a relationship to each other; for example, when a picture of a rainbow (which most people agree is "good") is displayed before the participant must categorize the word "puppy" (which most people also agree is "good") as either good or bad.

In the time-reversed version of this experiment, Bem asked participants to categorize a word as good or bad before the picture prime was flashed on the screen. He found that participants were faster at categorizing the word when it was replaced by pictures of the same valence; in other words, when "good" words were replaced by "good" pictures and when "bad" words were replaced by "bad" pictures. In fact, the participants were faster by . . . 15 milliseconds.

Wait, really, that's all?

The forward and time-reversed versions of a classic priming experiment

Most of Bem's effects are like this -- small both practically and statistically. The fact that these effects are so small makes me suspicious that Bem was cherry-picking his results. How many other failed experiments did he conduct before choosing these nine to present in a paper?

However, the experiments that he did choose were sufficiently rigorous to pass the peer review process of the flagship social psychology journal, the Journal of Personality and Social Psychology. Even though the paper has not yet been officially published at JPSP, it has already generated a large controversy among psychologists, several failed replications, a rebuttal from a group of statisticians, a report in the New York Times, and more than 98 news articles in a quick search of Google News.

Of course, if you examine some of the comments of the news coverage of the article, the article has also generated a large volume of responses from psi skeptics who lambaste both Bem and psychological research in general.

So, what are the likely implications of Bem's article for psychology?

With absolutely no demonstrable evidence in physics for a causal mechanism through which psi can operate, I have little doubt that time will uncover either statistical or methodological shenanigans that can account for Bem's findings. The history of psi research is a veritable case study in how these problems occur.

However, what concerns me about Bem's article is the probable backlash from the general public against psychology. I'm talking about comments like this:
Psychology is such a joke. A demonstration of future events influencing present events would be one of the most important (if not *the* most important) findings in the history of mankind. Yet this demonstration doesn't end up in Science or Nature, but is published in the Journal of Personality and Social Psychology? And some wonder why psychology is still considered pseudoscience....
Parapsychology has clear history of scientific shenanigans, and yet the publication of parapsychological articles in major psychology journals encourages people to lump parapsychology with good, rigorous, reputable psychological research. In the midst of politically motivated attempts to drastically cut NSF funding for the social sciences, this kind of negative attention for psychology has never been more unwanted.


  1. ABC news has now also picked up the story:

  2. Welcome back to the blogosphere! I picked up some of the buzz about this story but hadn't read any of the details, so I appreciate the summary.

  3. Thanks! I noticed that you yourself have had a fairly long absence. It feels nice to be writing again.

    The story has been getting a disconcerting amount of press, and a lot of buzz among social psychologists. It's depressing to think that Congress may be making funding decisions when this article comes out.

  4. Bem had an interview by Stephen Colbert about his "evidence" for precognition. Is it just me, or does he sound more like an old conspiracy theorist than like a scientist in the interview?


  6. A well written article. Intelligently put, I enjoyed the read.

  7. I like all stories about extra sensory perception. I am into clairvoyant information big time.

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