mind & bodyWikipedia

Déjà vu is a memory illusion that about two-thirds of people have experienced

the gist

Déjà vu, French for already seen, is the feeling that you have lived through the present moment before. It is a memory illusion: the sense of recognition is strong, but the time, place and context of the supposed earlier experience are unclear or impossible to pin down. Around two-thirds of surveyed people report having it at least once. Occasionally it appears as a symptom of seizure auras, and some researchers link frequent or unusual episodes to neurological or psychiatric conditions. In ordinary life it is more common among people with higher socioeconomic status, more education and younger ages. It is also more reported by people who travel often, watch many films or remember their dreams well. Most people experience it as a brief, harmless glitch.

how it works

Familiarity and recollection are normally processed together, so a feeling of recognition usually comes with a memory of where it came from. Explanations suggest a brief mismatch in brain processing can make a new moment feel familiar before the brain works out that it is new.

so what

Déjà vu shows that the sense of familiarity and the memory of an event can come apart, which says something about how the brain tags experiences as known. It is also a useful example for researchers studying how memory errors feel from the inside.

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Adapted from Wikipedia, the free encyclopedia · CC BY-SA 4.0

Illustrative photo · Sep nabi, CC BY-SA 4.0, via Wikimedia Commons