Can we predict the future? In 2011, Bem published a paper describing results from 9 experiments suggesting that we can. The research was quickly debunked and became part of what kicked off the movement to correct replicability issues in psychological science. Alas, there is no evidence that we have the powers of prediction.
We do, however, have a feeling that we can predict the future when experiencing déjà vu. Déjà vu, French for “already seen,” is the memory illusion of reliving an experience that was never experienced and knowing that it was not.
You know what I’m talking about, after all, it occurs in about two-thirds of us. The fleeting illusion does not happen very often; about once every few months in younger people and less so as we age. It’s made appearances in pop culture, for example, Beyoncé released an album “Déjà Vu” in 2006. The title song may get your toes tapping but you can appreciate that artistic license was taken with the lyrics:
“Baby, I swear it’s déjà vu
Know that I can’t get over you
‘Cause everything I see is you
And I don’t want no substitute
Baby, I swear it’s déjà vu”
[Beyoncé, I’m available for consultation if you’re planning on recording more songs about topics related to cognitive science.]
Alongside déjà vu is a sense of knowing what will happen next. Cleary and Claxton (2018) induced déjà vu to measure if participants could predict what would happen next. They could not. Instead of actual predictive abilities, feelings of predictive abilities were associated with reports of déjà vu. This supports the idea that in déjà vu, retrieval does not occur, but familiarity does.
If feelings of familiarity persist, then déjà vu may also be associated with feelings of postdiction. Postdiction is believing that an event occurred as it was predicted. This is the topic of research described in a paper by Cleary, Huebert, McNeely-White, and Spahr that was recently published in the Psychonomic Society’s journal Psychonomic Bulletin & Review.
Cleary and colleagues proposed that familiarity would persist which would lead people to believe that their predictions were accurate. In other words, they would have feelings of postdiction. They tested whether feelings of postdiction were associated with déjà vu, and whether familiarity was related to the feelings of postdiction.
To induce déjà vu in the lab, participants watched a 20-minute video of a virtual tour of environments created in the video game SimsTM (you can see an example here). The scenes were similar, but not the same, to those that they would later be tested on to bring about feelings of déjà vu.
Before the test phase, participants were given the following definition of déjà vu:
“Déjà vu is the feeling of having been someplace or done something before, without being able to pinpoint why and despite knowing that the current situation is new.”
During the test phase, participants viewed a series of short video clips of tours SimsTM environments. Video clips stopped just before a left or right turn was made and just after the turn was made. The example below shows a screenshot of a video clip that stopped before the turn.
To measure feelings of déjà vu and prediction, for each of the video clips that stopped short of the turn, participants answered “yes” or “no” to the question, “Did this scene prompt you to experience déjà vu?” They next answered “yes” or “no” to the question, “Do you have a sense of knowing which way to turn?” As in, did they sense an upcoming right or left turn? In the second experiment, they also rated the level of familiarity of the scene on a scale from 0 (very unfamiliar) to 10 (very familiar).
The example below shows a screenshot of a video clip that stopped after the turn.
To measure feelings of postdiction, for each of the video clips that stopped after the turn, participants answered the question, “Did the scene unfold the way you expected?” by providing a rating between 0 (definitely unfolded differently) to 10 (definitely unfolded exactly as expected). In the second experiment, participants responded “yes” or “no” to the same question and rated the level of familiarity of the scene on a scale from 0 (very unfamiliar) to 10 (very familiar).
Feelings of prediction were reported more with reports of déjà vu than non-déjà vu in both experiments. This finding replicates previous results by Cleary and colleagues.
As shown in the figure below, feelings of postdiction were also greater with reports of déjà vu than non-déjà vu in both experiments. Interestingly, there was a bias in the opposite direction with non-déjà vu reports (i.e., the bar falls below baseline).
Ratings of familiarity were higher with déjà vu reports, which also replicates previous results. And, as hypothesized, higher ratings of familiarity were associated with reports of postdiction. The figure below shows the relationship of familiarity to the postdictive bias before and after the turn.
The results are in line with the idea that the feelings of familiarity that accompany déjà vu are related to feelings of postdiction. This finding could lead to a better understanding of biases, such as the hindsight bias. The hindsight bias is the belief that an outcome was more predictable than it actually was and has been linked to postdictive illusions.
Cleary and colleagues concluded that
“Determining whether familiarity drives both déjà vu and the postdictive bias is an important future direction.”
I agree. And, after reading the details of that future research, I’ll claim that I knew them all along.
Psychonomics article focused on in this post:
Cleary, A. M., Huebert, A. M., McNeely-White, K. L., & Spahr, K. S. (2019). A postdictive bias associated with déjà vu. Psychonomic Bulletin & Review. https://doi.org/10.3758/s13423-019-01578-w
