Write the word "door" as fast as you can, over and over. Within about a minute, there is a good chance it will start to look wrong, as if it were a string of letters someone had tricked you into accepting as a word.
Psychologists call that unsettling flip jamais vu, French for "never seen." It is the mirror image of déjà vu, and researchers have found a remarkably simple way to produce it on demand. Their work won the 2023 Ig Nobel Prize for Literature, and newer findings are adding fresh clues about why it happens.
