As the great Carl Sagan once put it, “extraordinary claims require extraordinary evidence”*. And as far as extraordinary claims go, suggesting that humans can possess psychic abilities is a pretty big one. But in 2011, that was the claim that was made in a famous psychology paper by Daryl Bem at Cornell University in New York.
In a basic memory experiment, the setup might be something like this. First, you give a group of participants a list of words to remember. Once they’ve had chance to try and commit the list to memory, you might give them a bit of a break, or ask them to do some sort of distractor task. Finally, you then give them a larger list of words – some of which they saw in the original list, some of which are new – and get them to say whether they recognise the words or not.
Bem’s study flipped this idea on its head across a number of different experiments. In one such test, he got participants to read a list of 48 words, and then immediately asked them to write down as many as they could remember. Then, he gave the participants a random subset of 24 words from the original 48, and asked them to type them out on a computer screen. In other words, the recall session came before the practice session. At face value, Bem’s findings were remarkable: he reported that in the initial recall test, participants seemed better at remembering words that they would see in the later practice session, than words that they wouldn’t see later on. In other words, people were better at recalling words that they would be told to remember in the future.
What’s going on?
Thinking about this in the most basic way, there are two explanations that can account for Bem’s findings: either precognition exists, or something went amiss during the course of the experiment that threw up an erroneous finding. The way to figure out which of these explanations is right is to run a replication.
As we’ve discussed before on the blog, one of the cornerstones of science is reproducibility. If the result of a study can be reliably repeated, then we can be surer that the result is a correct one, and in turn use it as a foundation for further research. This is all the more important when a study suggests that something as extraordinary as precognition might actually exist.
Unfortunately, this is where things get a little sticky. In 2012, Stuart Ritchie, Richard Wiseman and Chris French attempted to replicate the memory test experiment explained above. Using exactly the same methods, they didn’t find any evidence of precognitive abilities. In the same year, a study by Jeff Galak at Carnegie Mellon University similarly showed over the course of seven experiments that there was no evidence for anything psychic going on. Other replication studies were attempted, but proved difficult to get published.
So, does the effect exist or not?
A failed replication doesn’t necessarily mean that the original study was wrong – it could simply be that something went awry in the replication study itself. However, Sagan’s words are worth bearing in mind here. For something so extraordinary as precognition to hold true, we should expect to see a wealth of supporting evidence. Unfortunately, Bem’s original findings don’t seem to hold up in a sea of negative results, and there is little further evidence to suggest that any form of psychic ability actually exists.
Bem’s study is notable not so much because it showed evidence of psychic ability, but more because of the controversy that followed. That such a strikingly counterintuitive finding could be published, but replications countering the claim struggled to find the light of day, started to ring alarm bells for the psychological community. This came at a time when psychologists were starting to grapple with the realisation that there were other serious issues that the discipline was facing. Five years on since Bem’s study was published, some of those issues are being fixed, but there’s still a long way to go.
* Sagan is credited as popularising the term, although the sentiment can be traced back to French scholar Pierre-Simon Laplace: “The weight of evidence should be proportioned to the strangeness of the facts.”
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