Pathways — Issue #001 — The Zeigarnik Effect

When designing products, I want to learn more about what makes us humans tick, what better place to start than with the brain. I’ve created Pathways to give you (and me) a glimpse into the power of understanding the human brain when designing a product or service.

In this series I examine behavioural biases and break down examples of products and services that have applied it effectively.

Are uncompleted tasks giving you a headache?

Before we begin, let me ask you something. Is there a task that is weighing on your mind? Perhaps you need to go and buy an anniversary card for your partner or maybe take the bins out? If you do have an incomplete task nagging you, rolling around in the back of your head, chances are you are experiencing the Zeigarnik effect.

What is the Zeigarnik Effect?

In the 1920s, conducted a (there’s a condensed english version found in the S “On finished and unfinished tasks”), in which she compared memory in relation to incomplete and complete tasks after her professor noticed that a waiter had better recollections of still unpaid orders.

In her experiment, Bluma set her test subjects tasks such as constructing cardboard boxes, making clay figures as well as mental problems such as puzzles and arithmetic.

The tasks were divided (without the subject’s knowledge) into two groups, A and B, and half of the subjects completed all of the A and none of the B tasks; the other half completed all of the B and none of the A tasks. This allowed Bluma to gather data on the subjects recall of the tasks, which would be easier to remember.

She found that the interruption of a task greatly improves its chances of being remembered. Of the 22 tasks used, 17 were remembered best when interrupted, 2 were equally well recalled regardless of interruption or completion, 3 were better recalled when completed.

Named for its pioneer, this phenomena was called ‘The Zeigarnik Effect’. Which we can now describe as: Uncompleted tasks will weigh on a person’s mind until it is done.

The state that our minds crave closure and certainty, this is why something that is incomplete stands out. explains why: when someone starts a task, they create a tension in their mind that pushes us to complete said task. Which improves cognitive access to any relevant information.

Through this continuous tension the task is easily remembered. The tension is only relieved once the task is completed.

So to relieve the tension, you’d better take the bins out.

Product Spotlight — Which product utilises the Zeigarnik Effect?

There are products out there that you may start to realise create that tension required in a person’s mind in order to better remember tasks. In this issue’s Spotlight is Todoist. (It’s a bit obvious, but hey, it’s only the first issue, I have to start somewhere)


For those that haven’t heard of, it is a delightful product that does what it says on the tin. It’s a to-do list. It embodies the Zeigarnik Effect quite well and serves as a stark example of what it is. Here is how Todoist describes itself on the website:

“From overwhelmed to on top of it. Todoist gives you the confidence that everything’s organized and accounted for, so you can make progress on the things that are important to you.”

In order for the Ziegarnik effect to take hold, Todoist needs to create tension. It does this by encouraging people to create (and complete) tasks in their todo list. Once even a single task is created, the tension begins.

It further helps maintain this tension in a non-intrusive way, by having the number of incomplete tasks on the notification badge over the app icon.

When the task is complete, it is a simple act of closure that relieves the tension, it feels good to tick if off of the list. Todoist makes this experience feel nicer with a little message encouraging you to enjoy your day.


Can the Zeigarnik Effect be taken too far?

In short. Yes.

Have you ever felt anxious knowing that you can’t get to your phone even though you have a text or missed call on your phone? Or even looking to see if you have collected enough sun to to defend your house from invading Zombies?

There are a lot of apps that utilise the Zeigarnik effect on your smartphone, whether they realise it or not. But all of these notifications can go too far and have a negative effect on us. Notifications on our phones can distract us from the tasks we are currently doing. A study conducted in 2015 () shows that notifications can disrupt task relevant thoughts and in turn have a negative effect on performance in that task.

If you choose to utilise the Zeigarnik Effect in your product or service, think about the surroundings of the person using it, will it be more of a distraction that the task at hand? Or will it be something that will help them accomplish their task?

Have you come across the Zeigarnik effect in any other products? Are there any other behavioural biases you’d like to see us analyse? Let us know in the comments below.

This issue is part of the Pathways series analysing how products and services utilise behavioural biases in order to design better products for humans.

Senior Product Designer at Zoopla, where I design for Humans, not users. Creating experiences that consider how we really interact with the world around us.

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store