Whether it strikes when you're visiting a new place that seems oddly familiar, or you feel like you've lived through a specific moment before, déjà vu is an eerie feeling. And it only gets weirder when it's coupled with the feeling that a person can predict what's about to come next. To investigate the mysterious phenomenon, cognitive psychologist Anne Cleary has developed a technique to induce déjà vu in people, and test whether it really helps them predict the immediate future.

Although it's a relatively common experience, nobody really knows why or how déjà vu occurs. Supernatural "explanations" include memories of past lives, precognitive dreams, parallel universes, or a glitch in the Matrix.

More scientific theories usually focus on how the brain processes memories. It's been suggested that the feeling might be the result of a communication lag between parts of the brain, so a current event is registered twice in quick succession. Maybe perceptions of that current event are, for some reason, momentarily bypassing short-term memory and heading straight into long-term. Or it could be the result of our brain double-checking its memories for errors.

Cleary, a cognitive psychologist at Colorado State University, has been studying the phenomenon for years, and believes that déjà vu is a memory phenomenon related to less unsettling experiences, like recognizing someone's face but being unable to figure out how you know them, or trying to recall a specific word that's "on the tip of your tongue."

"My working hypothesis is that déjà vu is a particular manifestation of familiarity," says Cleary. "You have familiarity in a situation when you feel you shouldn't have it, and that's why it's so jarring, so striking."

In order to study the phenomenon, Cleary and her collaborators developed a method to induce a sense of déjà vu in test subjects. Using the simulation game The Sims, the researchers built a series of virtual rooms, some of which were spatially identical to each other yet decorated to look like completely different spaces. For example, a garden location and a junkyard location would be designed with exactly the same layout but using different objects and textures. In the former, the object to the viewer's left was a hedge, while in the latter it looked like a pile of rubble.

People wearing virtual reality headsets were teleported through a series of these locations, with the two spatially-identical-yet-thematically-unrelated scenes sprinkled through. Sure enough, the test subjects reported feelings of déjà vu when they entered the second of the two similar scenes, even though they'd never visited that specific location before.

"We cannot consciously remember the prior scene, but our brains recognize the similarity," says Cleary. "That information comes through as the unsettling feeling that we've been there before, but we can't pin down when or why."

The researchers also wanted to experiment with the associated feeling of premonition that some people report alongside déjà vu episodes. To do so, the study participants were moved through each location in a specific way, with the path through the two test locations being identical. The videos were paused before they reached the final turn, and participants were asked to predict which direction that turn would be.

Although half the subjects reported a strong feeling of premonition, they were no better at recalling the right answer than if they were guessing randomly – this was the case even those that were pretty confident they would be correct. The team concluded that although déjà vu can make us feel like we can predict the future, it unsurprisingly doesn't help.

In future studies, the team plans to test whether a person's strong conviction that they can predict the future is due to "hindsight bias." That means that after the event, a person could convince themselves that they knew what was about to happen, and that assumption could be reinforced if the person by chance managed to guess the correct answer.

The research was published in the journal Psychological Science.

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