The Zeigarnik effect and memory: obsessive thoughts
Have you ever felt anxious or even guilty about an unfinished task? Have you ever put work off until later and then lain awake at night, replaying that unfinished task in your mind? Why can we forget something important after a couple of days, but can’t get some trivial detail out of our heads for years?
This phenomenon isn't driven by conscience, a habit of finishing what you start, or a perfectionist streak. Everyone experiences this effect to some degree, and psychologists have studied it for decades.
If this has happened to you, then you have experienced the Zeigarnik effect. At its core, the Zeigarnik effect explains how unfinished tasks create internal tension that keeps pulling our thoughts back to them.
About the Zeigarnik effect
Your brain never rests. It keeps circling back to the tasks you've started. On one hand, it fuels anxiety and unease. On the other, it gives us the drive to finish what we've started.
TV writers and showrunners rely on the Zeigarnik effect to make you wait for the next episode. Episodes are deliberately crafted around cliffhangers that leave the audience eager for the next installment.
You probably encountered this effect back in school. Remember how well you knew all the information before the exam? After successfully passing the exam, most of this knowledge simply evaporated, and a few days later, it would be much more difficult to pass the same exam. This is normal. The task is done, the information is no longer needed, and your brain simply erases it.
How was this effect discovered?
In the 1920s, psychologist Bluma Zeigarnik was dining in a restaurant when she noticed the waiter taking orders without writing anything down. Even large orders came out exactly right. Did this waiter have an exceptional memory? When she asked him, he replied that his colleagues worked the same way — and that his own memory was nothing special. Zeigarnik discovered that the waiter remembered all the orders that had not yet been served, but forgot them almost immediately once the dishes were delivered to the table. This led her to think that the brain perceives completed and unfinished tasks differently — keeping active tasks in focus until they are done, then releasing them to make room for new ones.
About Zeigarnik's research
A series of experiments followed in which students were given various cognitive tasks. The researcher set arbitrary time limits for each task and could announce that time was up, even if the task wasn't finished.
Zeigarnik found that unfinished problems were recalled by students 90% more often than completed problems. She concluded that interrupted problems are remembered significantly better than solved ones. Her 1927 paper, “On Completed and Unfinished Problems,” lays out the original evidence for this effect.
Other studies supporting the Zeigarnik effect
The existence of the Zeigarnik effect was confirmed by British psychologist Alan Baddeley. He used sets of anagrams in his experiment. Participants had a limited time to solve each anagram; if they failed, they were given the answer.
Interestingly, all participants were able to recall the unsolved anagrams significantly better than those they had successfully solved. So completed tasks bring satisfaction and quickly fade from memory, making room for new ones.
Criticism
Not all studies have confirmed the Zeigarnik effect. Experiments show that motivation significantly shapes the effect. Tasks driven by strong personal motivation are remembered better when completed than when interrupted.
Highly motivated people also worry more about tasks they can't complete than less motivated ones do.
How the Zeigarnik effect works
Our short-term memory has a limited capacity — we can only hold a small amount of information for a short period.
Here you can take a free short-term memory test.
To remember more information, we need to periodically retrieve it from long-term memory, which can require significant mental effort. The more information we try to remember at once, the more difficult it is to recall later. This is how the brain conserves energy.
This is especially important for waiters, who need to remember the details of their customers' orders until they finish their meal and leave the restaurant.
Brainteasers and crossword puzzles are excellent tools for exercising this process. They help sharpen your recall and significantly improve memory retention. This mental workout is actually driven by the Zeigarnik effect. We essentially juggle the information, letting it drop and picking it back up. The more we focus on unfinished processes, the less likely we are to forget about them.
Interestingly, even long-forgotten tasks can linger in your subconscious, carrying a trace of stress that affects your behavior. Such tasks should be completed, if possible.
The Zeigarnik effect offers a clear window into how our memory works. When information is perceived, it is stored in short-term memory. If information is used often, it can gradually move to long-term memory, though most memories fade before they ever get there. Starting a task creates psychological tension that does not dissipate until the task is completed. This tension keeps pushing us to finish the task just to make it go away. Our desire to complete tasks affects our memory and behavior. This is why we tend to seek a sense of completion and dislike uncertainty.
How to use the Zeigarnik effect to your advantage
Can you use the Zeigarnik effect to your advantage? Yes — it can serve as a time management tool and help you quickly achieve small goals. When you start a task, try to complete it before moving on to the next one. This way, you will not have a lot of unfinished tasks that create a feeling of psychological burden.
Study in small chunks for better retention. Do not wait until the last moment before an exam to start studying. Instead, try to space out your study sessions over several days. This way, the information will more effectively transfer from your short-term memory to long-term memory, and you will be able to remember more.
If you need to memorize something important in a short time, take short breaks. Repeat a few times and then take a break. Don't repeat the information over and over again. Try to revisit the material in the back of your mind while you focus on something else.
Overcoming Procrastination
The hardest part is starting a task. At that point, we'll do anything to put the work off. Our brain resists. To overcome this, break the task down into several small steps. As soon as you start the first step, you'll find yourself thinking about the next steps.
By doing this, you can quickly achieve your goal because the task will be completed much more efficiently than if you try to do everything at once. Your mind will have a clearer picture of the path to your goal. You can finish one step and smoothly move on to the next.
The importance of interest and attention
Today, some methods of memorizing information use the Zeigarnik effect. For example, filmmakers, bloggers, and reporters use it to keep the audience's attention. They end a series or video on an unresolved note, leaving you waiting for what comes next. Studies show this interruption tactic boosts both audience engagement and recall.
Marketers also tap into the Zeigarnik effect — leaning on the first seconds of a video, unexpected plot twists, and deliberate ambiguity in characters' actions. It helps viewers remember the ad.
Mental well-being
People need to complete the tasks they start. Unfinished tasks nag at us and rob us of peace. Of course, some people tolerate unfinished business just fine, but most of us feel uneasy about it.
The Zeigarnik effect is a legacy of evolution. The more we are bothered by unfinished business, the faster we start to complete it, and this works in our favor. After completing the task, we feel more confident, calm, and satisfied.
Conclusion
Waiters are a classic example: they remember every detail of an order while it is still being served, but forget it almost immediately once the dishes reach the table. Want to ensure you get a product or service faster? Take a tip from the Zeigarnik effect — hold off on the final payment until the very last moment. Keeping the ‘task’ open in the provider's mind ensures they stay focused on completing it.