In 1927, Gestalt psychologist Bluma Zeigarnik noticed a funny thing: waiters in a Vienna restaurant could only remember orders that were in progress. As soon as the order was sent out and complete, they seemed to wipe it from memory.
Zeigarnik then did what any good psychologist would: she went back to the lab and designed a study. A group of adults and children was given anywhere between 18 and 22 tasks to perform (both physical ones, like making clay figures, and mental ones, like solving puzzles)—only, half of those tasks were interrupted so that they couldn’t be completed. At the end, the subjects remembered the interrupted tasks far better than the completed ones—over two times better, in fact.
Zeigarnik ascribed the finding to a state of tension, akin to a cliffhanger ending: your mind wants to know what comes next. It wants to finish.
On writing, memory, and forgetting: Socrates and Hemingway take on Zeigarnik in Scientific American, by Maria Konnikova
Lauren Bacall by Martin_Klasch on Flickr.