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. It wants to keep working – and it will keep working even if you tell it to stop. All through those other tasks, it will subconsciously be remembering the ones it never got to complete. Psychologist Arie Kruglanski calls this a Need for Closure, a desire of our minds to end states of uncertainty and resolve unfinished business. This need motivates us to work harder, to work better, and to work to completion. It adds impetus to minds that may otherwise be too busy or oversaturated to bother with the details. In other words, it ensures that those orders will stay in the waiters’ heads until it is certain that your food will hit the table as promised.

The Zeigarnik Effect that has been demonstrated many times, in many contexts – but each time I see it or read about it, I can’t help but think of an admonition that came centuries before Ms. Zeigarnik sat down to her Viennese coffee: Socrates’ reproach in The Phaedrus that the written word is the enemy of memory. In the dialogue, Socrates recounts the story of the god Theuth, or Ammon, who offers the king Thamus the gift of letters:

This, said Theuth, will make the Egyptians wiser and give them better memories; it is a specific both for the memory and for the wit. Thamus replied: O most ingenious Theuth, the parent or inventor of an art is not always the best judge of the utility or inutility of his own inventions to the users of them. And in this instance, you who are the father of letters, from a paternal love of your own children have been led to attribute to them a quality which they cannot have; for this discovery of yours will create forgetfulness in the learners' souls, because they will not use their memories; they will trust to the external written characters and not remember of themselves. The specific which you have discovered is an aid not to memory, but to reminiscence, and you give your disciples not truth, but only the semblance of truth; they will be hearers of many things and will have learned nothing; they will appear to be omniscient and will generally know nothing; they will be tiresome company, having the show of wisdom without the reality.

Could this be the Zeigarnik effect in action, long before the psychological concept was discovered or explored in any great detail? When we no longer have the impetus to remember, when we are certain that what we know has been put into action—be it in the form of a completed order or a book that we know we’ll be able to reference at any future point—why take up precious mental real estate that can be put to use on other tasks that we can’t be so sure of completing or knowing how to complete should that need arise?

Authors long after Socrates have noted that very thing. I’ve always remembered Ernest Hemingway telling George Plimpton in his 1958 Paris Review interview that, “though there is one part of writing that is solid and you do it no harm by talking about it, the other is fragile, and if you talk about it, the structure cracks and you have nothing.” Hemingway continues:

I cannot believe Twain ever “tested out” Huckleberry Finn on listeners. If he did they probably had him cut out good things and put in the bad parts. Wilde was said by people who knew him to have been a better talker than a writer. Steffens talked better than he wrote. Both his writing and his talking were sometimes hard to believe, and I heard many stories change as he grew older. If Thurber can talk as well as he writes he must be one of the greatest and least boring talkers. The man I know who talks best about his own trade and has the pleasantest and most wicked tongue is Juan Belmonte, the matador.

In this view, talking something through—completing it, so to speak, off the page—impedes the ability to actually create it to its fullest potential. Somehow, that act of closure, of having talked through a piece of work, takes away the motivation to finish. It’s like the order has already been delivered to the waiting customer. Once done, it escapes from the mind to make way for the next client. And the best of both worlds may or may not exist.

Hemingway's words came from experience. When his wife lost a suitcase that contained all existing copies of his short stories, the work was, to his mind, gone for good. He had written himself out the first time around. He couldn’t recapture it--whatever it was--again. He even fictionalized the process in the short story, “The Strange Country”: the writer whose stories have been lost finds it impossible to remember. “It’s useless,” he tells his sympathetic landlady. “Writing [the stories] I had felt all the emotion I had to feel about those things and I had put it all in and all the knowledge of them that I could express and I had rewritten and rewritten until it was all in them and all gone out of me. Because I had worked on newspapers since I was very young, I could never remember anything once I had written it down; as each day you wiped your memory clear with writing as you might wipe a blackboard clear with a sponge or a wet rag.”

(Or, take the more modern story of the blind woman who didn’t realize her pen had run out of ink and who wrote the opening of her novel only to have her son tell her it was blank. Or the advice offered by the author Justin Taylor: “Don't take notes. This is counterintuitive, but bear with me. You only get one shot at a first draft, and if you write yourself a note to look at later then that's what your first draft was—a shorthand, cryptic, half-baked fragment.” It’s an oft-repeated tale.)

Hemingway seems to be, in many ways, on the same page as Socrates—and the same page as Zeigarnik and her foundational studies of our memories’ curious quirks. What’s more, the more we know about memory, the more true it seems to be that we somehow let go of the information that we no longer feel we absolutely must hold on to. Last year, a study by Betsy Sparrow and colleagues, published in Science, suggested that people are far less able to recall information that they expect to be able to have access to in the future. Instead, they remember where and how to find that information.

It’s Socrates’ “trust to the external written characters” brought to life. And to me, at least, there is something a bit disconcerting in the knowledge that my brain may choose to forget things just because it knows it doesn’t absolutely need to remember them. (It bears note that one of Sparrow’s paradigms involved priming subjects with the thought of computers. A reminder outside conscious awareness that we have the technology to do our remembering for us is enough to make us remember just a little less well.)

I would never give up the ability to record, to access, to research endless topics at the click of a button. But, with Hemingway and Socrates never far from mind, I may be slightly more cautious about how I use that ability.

The Zeigarnik effect is a powerful motivating force. And a motivated mind is a mind that is much more capable of thought and accomplishment - even if it does sometimes need to use a cheat sheet to remember just what it wanted to include, be it in a story or an order. I, for one, know that I will always prefer a waiter who writes my order down to one that remembers it—however urgently—all in his head.

Kruglanski, A., & Webster, D. (1996). Motivated closing of the mind: "Seizing" and "freezing." Psychological Review, 103 (2), 263-283 DOI: 10.1037//0033-295X.103.2.263

Sparrow B, Liu J, & Wegner DM (2011). Google effects on memory: cognitive consequences of having information at our fingertips. Science (New York, N.Y.), 333 (6043), 776-8 PMID: 21764755