The Zeigarnik effect: why unfinished tasks keep you up

The Zeigarnik effect, named after the psychologist Bluma Zeigarnik, who reported it in 1927, is the claim that you remember interrupted, unfinished tasks better than finished ones. That memory advantage has replicated poorly, and a 2025 meta-analysis of the studies that followed found none on average. What holds up better is the pull: unfinished tasks tend to get resumed and to intrude on your thoughts, and in experiments, writing a specific plan for a task quietened those thoughts without any of the work being done.

The 11pm meeting

The lamp goes off, and the meeting starts. Nobody called it and nobody chairs it. The agenda is everything you might have forgotten: the email you meant to answer, the form due Friday, the birthday that is either this Saturday or next. Each item gets read out, then read out again, as if saying it twice might settle it.

Nothing gets decided, because nothing on the list can be done from bed. What each item wants to know is whether anyone has it in hand.

This is the experience the Zeigarnik effect usually gets quoted to explain. The explanation is half right, and the right half comes with a fix.

Zeigarnik and the waiter

The effect has an origin story, and in the sources it isn’t Zeigarnik’s. In the best-known version, from E. G. Boring’s 1957 history of experimental psychology, Zeigarnik’s supervisor, Kurt Lewin, was in a Berlin restaurant with friends, deep in one of his long conversations. He called the waiter over, asked what he owed, was told at once, and paid. The talk went on. Later Lewin called the waiter back and asked how much he had been paid. The waiter no longer knew.

Donald MacKinnon, who was at the table, told it differently. In his account, quoted in A. J. Marrow’s 1969 biography of Lewin, the waiter had kept everyone’s order in his head without writing anything down. When Lewin asked him half an hour later to write the bill out again, he was indignant: “I don’t know any longer what you ordered”, he said. “You paid your bill.”

Treat it as an anecdote. It was written down decades afterwards, in two versions that don’t agree on what the waiter remembered. The psychologist Colin MacLeod, who sets them side by side in his review of Zeigarnik’s work, points to what they share: the waiter remembered the transaction while it was still open.

Lewin’s theory was that an intention creates a kind of tension, released when the task is done. Zeigarnik, his doctoral student at the University of Berlin, turned that into an experiment. In her main study, 32 adults worked through 22 short tasks, among them winding thread, folding paper, multiplication and drawing a vase, each meant to take 3 to 5 minutes. Half were interrupted just as the person was most absorbed. Afterwards she asked them to list every task they could remember. Across her first 4 experiments, people recalled about twice as many interrupted tasks as completed ones, and around 8 in 10 participants showed the pattern.

Is the Zeigarnik effect real?

Two different claims travel under the name, and the evidence treats them differently.

“You remember interrupted tasks better.” This is the effect Zeigarnik reported, and it’s the one that hasn’t survived. Replications were mixed from the start. Van Bergen’s 1968 dissertation repeated the original as closely as she could: of her 34 participants, 9 recalled more interrupted tasks and 20 recalled more finished ones. By MacLeod’s count, fewer than a third of the 44 replication attempts van Bergen reviewed found the effect.

The fullest tally is a 2025 meta-analysis by Romain Ghibellini and Beat Meier, which pooled 38 publications that used Zeigarnik’s method. The ratio of interrupted to completed tasks recalled came out at 0.99, which is to say equal, and leaving out Zeigarnik’s own data didn’t move it. They also show that the way Zeigarnik averaged her ratios overstated the effect. In their words: “We found no memory advantage for unfinished tasks but found a general tendency to resume tasks.” Their guess at why Zeigarnik saw it is that her participants took a professor’s tasks unusually seriously, a condition that’s hard to recreate in a modern lab. MacLeod’s summary is blunter: “At best, it would appear to hinge on certain individual difference characteristics; at worst, it is simply not replicable.”

“Unfinished goals keep pulling at you.” This one holds up better. In the same meta-analysis, people went back to an interrupted task roughly 67% of the time when given the chance, across 21 publications, against a chance rate of 50%. That is the Ovsiankina effect, after Maria Ovsiankina, who reported it from Lewin’s lab in 1928. And in the experiments below, people who had just written about unfinished tasks reported more intrusive thoughts about them while reading a novel than people who had written about tasks they’d already finished.

So the honest version of this page’s title: unfinished tasks don’t get a better seat in memory. They keep asking for attention. At 11pm that’s the half that matters, because you don’t need a better memory of the tax form. You need it to stop interrupting.

Decided, not done

In 2011, E. J. Masicampo and Roy Baumeister at Florida State University tested a question the Zeigarnik story never asked: does the pull stop only when the task is finished?

In their first study, 73 undergraduates were split into 3 groups. One group wrote about 2 important tasks they had to do in the next few days, ones they hadn’t yet worked out how or when to do. A second group did the same, then planned each task: how, when and where they’d do it. A third wrote about 2 tasks they had already finished. Then everyone read the opening 3,200 words of a popular novel and answered 8 questions on it.

The unfinished-task group reported more intrusive thoughts about their tasks during the reading and got fewer questions right. The planners looked like the people whose tasks were done: no more intrusions, and no drop in comprehension. Nobody in the plan group had done any of the work. Deciding was enough.

The paper reports 6 studies in all, and 3 details from them matter if you want to use this:

• The plan has to be specific. In one study, people who listed several possible ways to get a task done, without committing to any of them, still had the intrusive thoughts. A committed plan, with a when and a where, quietened them.
• The plan has to be meant. In another, the planners’ freedom from distraction went with actually carrying out their plan later. The authors note that this link was observed, not manipulated, so it falls short of proof.
• It quietens thoughts, not feelings. Planners felt as anxious about their tasks as people who made no plan. The tasks just stopped interrupting them.

The obvious objection is that this is procrastination with paperwork: write it down, feel done, never do it. The paper points the other way. In the study where people were told the best strategy for a later task, 70% of those who committed to a specific plan used it, against 13% of those who only promised to try their best. The authors do flag one cost: a plan can push a goal far enough out of mind that you miss a new opportunity to get it done.

Keep the limits in view, too. This is one paper, built from students in short lab sessions and paid online volunteers, and the intrusions were mostly measured by asking people afterwards. The plans it tested are close kin to the if-then plans studied as implementation intentions, which have a larger record of their own.

Does writing a to-do list before bed help?

There is one direct test. Michael Scullin and colleagues at Baylor University brought 57 healthy adults aged 18 to 30 into a sleep lab for a night. Before lights out, each spent 5 minutes writing by hand. Half, chosen at random, wrote a to-do list for the next few days; the other half wrote about tasks they had completed over the previous few days. Sleep was measured with polysomnography, the sensor recording that sleep research treats as its gold standard, rather than by asking people how they slept.

The to-do group fell asleep faster: about 16 minutes on average, against about 25 for the completed-list group. And within the to-do group, the more specific the list, the faster people fell asleep. The researchers had gone in with two opposite predictions, since writing down tomorrow’s tasks could as easily have stirred up worry. In this study it didn’t.

The limits are real. It was a single night, the first in an unfamiliar lab, which the team chose on purpose as a stand-in for an occasional bad night. The sleepers were young and had no sleep disorders. And the comparison was another kind of writing, not no writing, so the study can’t say whether the to-do list helped or the completed list hurt; the authors expect a bit of both. As the next step they called for a trial over many nights outside the lab, in people with and without insomnia. On its own, this is one encouraging study.

A two-minute evening capture

Put the two findings together and you get a short routine for the end of the day. It’s a practice built from the studies, not a tested protocol: Scullin’s sleepers wrote for 5 minutes, so treat 2 minutes as a starting point, not a finding.

1. The task. Write down each thing that’s talking, one line each, in the order it arrives. Paper by the bed is enough.
2. Its next step. Not “taxes” but “find last year’s bank statements”. The smallest physical action that moves it.
3. When. A day, and if you can, a time and a place: “Thursday, 9am, at my desk”. Pick one. In the 2011 paper, listing options without choosing one didn’t quieten the thoughts.

Some items won’t take a date tonight. Give those a time to decide instead, such as “look at this in Sunday’s weekly review”. That’s a plan too.

Then close the notebook. You may still feel uneasy about the tax form; the planners in those studies did. What should change is that it stops being read aloud every few minutes. In the morning the list is where you start, and three lines are enough to turn it into a day.

Tonight, try it on whichever item has already come up 3 times. Give it a next step and a day, and see whether it comes back.

Sources

• Ghibellini, R., & Meier, B. (2025). Interruption, recall and resumption: a meta-analysis of the Zeigarnik and Ovsiankina effects. Humanities and Social Sciences Communications, 12, 962. https://doi.org/10.1057/s41599-025-05000-w
• MacLeod, C. M. (2020). Zeigarnik and von Restorff: The memory effects and the stories behind them. Memory & Cognition, 48(6), 1073–1088. https://doi.org/10.3758/s13421-020-01033-5
• Masicampo, E. J., & Baumeister, R. F. (2011). Consider it done! Plan making can eliminate the cognitive effects of unfulfilled goals. Journal of Personality and Social Psychology, 101(4), 667–683. https://doi.org/10.1037/a0024192
• Scullin, M. K., Krueger, M. L., Ballard, H. K., Pruett, N., & Bliwise, D. L. (2018). The effects of bedtime writing on difficulty falling asleep: A polysomnographic study comparing to-do lists and completed activity lists. Journal of Experimental Psychology: General, 147(1), 139–146. https://doi.org/10.1037/xge0000374
• Zeigarnik, B. (1927). Das Behalten erledigter und unerledigter Handlungen. Psychologische Forschung, 9, 1–85. https://doi.org/10.1007/BF02409755