Déjà vu

Fernando Kaskais

Oct 28

Photo by Christopher Anderson/Magnum

Have you been here before? The eerie sensation is the shadow of your mind searching inward for clues to its own survival

Anne Cleary is professor of psychology at Colorado State University where she leads the Human Memory Lab. She is the co-editor of Memory Quirks (2020) and the co-author of The Déjà Vu Experience (2nd ed, 2021).

Déjà vu, the eerie sense that something new has been experienced before, has confounded us for hundreds of years. Along with the public, philosophers, physicians, intellectuals and, more recently, scientists have tried to get to the bottom of the phenomenon. Potential explanations have ranged from double perception (the idea that an initial glance at something was only partially taken in, leading to déjà vu upon a second, fuller glance) to dissolution of perceptual boundaries (a brief blurring of boundaries between the self and the environment) to seizure activity to memory-based explanations (the idea that déjà vu results from a buried memory). Now, research emerging from my lab and others suggests that déjà vu is not just a spooky experience, but a possible mechanism for focusing attention – perhaps an adaptive mechanism for survival shaped by evolution itself.

I first became interested in the topic after reading the paper 'A Review of the Déjà Vu Experience' (2003) by the psychologist Alan S Brown – probably the first treatment ever to appear in a mainstream psychology journal. Writing in the Psychological Bulletin, Brown described survey studies, case reports and theoretical ideas culled from more than a century's worth of writings on déjà vu. Much of the available literature on déjà vu at the time came from non-mainstream sources (and some were even of a paranormal flavour). Still, from this largely fragmented literature, Brown managed to winnow some important clues and presented them in a language that cognitive scientists could work with and act upon: data and theory. The data from the survey studies provided useful empirical starting points, and the very old theories of déjà vu that Brown reviewed provided a scaffolding for devising highly specified hypotheses that could be tested in a lab.

From the large collection of surveys conducted over the years, Brown determined that roughly two-thirds of people experience déjà vu at some point in their lives. He also reported that the likelihood of experiencing déjà vu decreases with age, and that physical settings (or places) are the most common trigger. The finding that déjà vu is most commonly elicited by scenes (as opposed to just speech or objects) was a particularly useful clue for scientists: a new theoretical approach to autobiographical and event memory emphasises a role of scenes in the ability to recollect past life events. Partly based on newer understandings that brain areas critical for first-person navigation through places may also underlie recollective memory ability, the idea is that the first-person perspective within a scene is a crucial facet of human memory. Consider the last dinner that you ate at a restaurant. What is this memory like? Can you 'see', in your mind's eye, where everyone else is sitting relative to you at the table? This illustrates how our ability to process, navigate through and mentally reconstruct our place within past scenes may be central to our recollective memory ability.

The critical role of our place within scenes in memory may also be why the centuries-old memorisation technique known as the Method of Loci (also called the Memory Palace) is very effective and used by competitive memorisers; it involves envisioning your to-be-remembered information within particular scenes along a route that you regularly take, or within a building that you know well. For example, to remember his talking points in their correct order for his TED talk 'Feats of Memory Anyone Can Do' (2012), the science writer Joshua Foer created a visualisation of different points throughout his house, each with a visual-image cue attached to it so that, when he did a mental walk-through of his house starting at a mental image of the front door, he would 'see' in his mind's eye an image cuing him for the next talking point.

In the foyer of his house, Foer had imagined Cookie Monster (the Muppet) on top of Mister Ed (the horse) as his cue to introduce his friend Ed Cooke at that point in the talk. Foer continued moving through various places within his image of his house to access his cues for the next talking points in the order in which he needed to raise them. For example, later on, when arriving at the kitchen in his mental walk-through of his home, he had imagined the characters from The Wizard of Oz along a Yellow Brick Road; this was his cue to describe how he had embarked on a journey and the many friends he met along the way. As Ulric Neisser, often considered the father of cognitive psychology, suggested decades ago, 'a sense of where you are' may provide a basis for recollective memory. Although déjà vu is more of a contentless sensation of memory than a recollection of autobiographical experience, the fact that it tends to be elicited by scenes hints at the possibility that it, too, emerges from the same basic scene-processing mechanisms that enable this 'sense of where you are'....

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https://aeon.co/essays/deja-vu-a-window-on-the-past-and-a-key-to-human-survival