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In fiction

Global amnesia is a common motif in fiction despite being extraordinarily rare in reality. In the introduction to his anthology The Vintage Book of Amnesia, Jonathan Lethem writes:

Real, diagnosable amnesia – people getting knocked on the head and forgetting their names – is mostly just a rumor in the world. It's a rare condition, and usually a brief one. In books and movies, though, versions of amnesia lurk everywhere, from episodes of Mission Impossible to metafictional and absurdist masterpieces, with dozens of stops in between. Amnesiacs might not much exist, but amnesiac characters stumble everywhere through comic books, movies, and our dreams. We've all met them and been them.

Lethem traces the roots of literary amnesia to Franz Kafka and Samuel Beckett, among others, fueled in large part by the seeping into popular culture of the work of Sigmund Freud, which also strongly influenced genre films such as film noir. Amnesia is so often used as a plot device in films, that a widely recognized stereotypical dialogue has even developed around it, with the victim melodramatically asking "Where am I? Who am I? What am I?", or sometimes inquiring of their own name, "Bill? Who's Bill?"

In movies and television, particularly sitcoms and soap operas, it is often depicted that a second blow to the head, similar to the first one which caused the amnesia, will then cure it. In reality, however, repeat concussions may cause cumulative deficits including cognitive problems, and in extremely rare cases may even cause deadly swelling of the brain associated with second-impact syndrome. Fictional depictions of amnesia are almost universally retrograde; Memento is a rare example of anterograde amnesia in fiction.

In science fiction involving a masquerade that hides magical or alien societies from humanity, such as Men in Black or the SCP Foundation, fictional organizations can induce deliberate amnesia via drugs or advanced technology to wipe the minds of those that view supernatural phenomena.