The secret of waiters who don’t write your order down

Ahh, a thing of beauty — a complete set.Image from:

If you grew up in Ireland or the UK, and liked football, there’s a pretty high chance you at some point had one of these things:

Image source

What was so great about these sticker albums? Where do I start?!

They certainly tapped into many of those things that make a product addictive. For example, uncertain rewards — you’d buy a pack of 6 stickers and have no idea what’s inside.

The thrill of getting a sticker you never had before — well it was pretty exciting. But in a lot of ways, these sticker albums tapped into the same part of our brains that have people out in the streets playing Pokémon Go.

One of the things that these sticker albums relied on (as does Pokémon Go!), is the idea of the zeigarnik effect. To highlight this, check out the image below:

This image comes from and I’ve edited it with Skitch.

A missing set. There is nothing worse than something missing. With these sticker albums, you’d get 80% of the album complete very quickly, but it would take forever to complete the whole thing — very similar to Pokémon Go.

The thing is, while our desire for completion is one thing, there’s another interesting fact about how our brains work when it comes to things that are incomplete:

You know exactly what stickers you are missing. You know exactly what Pokémon you don’t have. In short, you can recall what you don’t have right away, what you actually have is not as important any more.

Ok, so to explain this, let’s start with the term ‘the zeigarnik effect’. What is the zeigarnik effect? This term was coined by Bluma Zeigarnik who first studied the phenomenon and published a research report in 1927. A short definition is:

In psychology, the Zeigarnik effect states that people remember uncompleted or interrupted tasks better than completed tasks.

Ever see a waiter at a restaurant take your order without writing it down? Look, it’s not a practice I’m happy about, but the truth is, they’re usually pretty good at remembering the order. Try asking them whenever you leave the restaurant what your table ordered though — chances are they’ve forgotten.

This little story above, adapted from an excellent piece on CogLode, is a great example of the zeigarnik effect in practice. That is the waiter secret.

Essentially, when we have a task in mind that’s incomplete, it sticks in our mind. We as human’s strive for completeness, and often feel uneasy until we achieve this. It also taps right into something else closely related — our need to finish things. It makes us feel good. Why? Endorphins.

It turns out that when you finish a complex task, your brain releases massive quantities of endorphins.

This effect can also be referred to as the ‘cliffhanger’ effect, popular in movies and TV shows. The show tantalises us with what’s coming next, but stops just short of telling us — forcing us to watch on to see what happens.

This used to be at the end of episodes or movies — with reality TV it happens at nearly every break in the show (Masterchef anyone?).

So what does it have to do with web design?

There are a few different things we can learn and apply to our design process, based on this phenomena.

Make better forms

I’ll be careful not to ramble on this one — I love forms. But how can we apply the Zeigarnik effect? Well, for one, exposing incomplete form fields is one way of tapping into the subconscious need to see ‘completeness’. Many landing pages use this idea, where a newsletter sign-up form is exposed and in view during a scrolling of the page.

In the top right of the Intercom blog you can always see the subscribe field, unfilled

Also helping with this, is inline validation. For example, let’s say a form has four fields. You enter the first field and a green tick shows up next to it and you’re into the second field. Sub-consciously your desire to fill out the rest of the fields increases, once you’re halfway through the task and the clear feedback to indicate you are halfway through the task enhances this. More on that one later.

Offering free previews with opt-ins

Another ‘landing page’ classic. Offering readers access to the start of an article, but encouraging them to ‘sign up’ to download the full white paper, or entering an email to access content is another way of ‘hijacking’ our need for completeness.

On this website (Newsela), you can see the title and the start of the content, but it starts fading as you read further, requiring an opt in. The need for completion can kick in here, particularly if it’s a relevant article for you!

An exaggeration of this can be seen in articles that seem to ‘fade out’ the ending, so that it’s right there, within touching distance — but you need to complete a task to access it. The above website shows an example of this.


LinkedIn’s profile is a great example of this, as is Acorn’s profile. In both cases they give you a percentage of ‘how complete your profile is’. In both cases, your profile contains all the necessary information to be useful — but they encourage you to invest more time in their app regardless.

Image from — how do I make it 100%!!
This is from my LinkedIn profile. I’m an ‘All Star’ — but they’ve still left a bit of a gap for me. This is the zeigarnik effect at it’s best!

I’ve definitely fallen into this trap. Striving for that 100%. This is a clever way of nudging you into investing more time into their app which taps into another psychological phenomena — the ‘sunk cost effect’. If you want to have a good read on that check out this paper.

This subject is also explored in Daniel Kanhemann’s ‘Thinking Fast and Slow’ and ‘Nudge’ by Richard Thaler.

Progress Bars

As I mentioned above in forms, adding progress bars is another great way to keep people engaged. When you see you’re 80% of the way through a task — the desire for completeness kicks in.

Showing the user the investment they’ve made, similar to the example above with gamification, will keep them engaged and more likely to complete a task.

On they use a progress bar to show how complete my application is. You’ll note I look to be about 20% done — all I did was click on the ‘START’ button!

This example above from also features something you’ll see out there in the wild quite a lot — all I did was click on start and it’s already telling me I’m about 20% up the progress bar.

These progress bars aren’t necessarily real representations of the complexity of the application. While this is a common practice and we can often be at peace with the idea of the bars not exactly matching the real-world progress percentage, as designers we should be careful not to exploit users.

If the first step is easy, takes 1 minute and is worth 20% then the next step is harder, takes 15 minutes and is also worth 20%, my probability of continuing drops. I stop trusting the interface and feel like it’s tricking me.

Bigger tasks = lots of smaller tasks

One of the main themes throughout this article, whether it be progress bars or gamification, is the idea of splitting a bigger task into smaller tasks. Allowing us to save and move onto the next step.

Users are much more likely to embark upon a (digital) journey when they can complete part of a task, save it and move on — and their cognitive load can be reduced as they complete smaller tasks.

This also ties in nicely with the very appropriately named process of ‘chunking’. In short:

Chunking is a term referring to the process of taking individual pieces of information (chunks) and grouping them into larger units. By grouping each piece into a large whole, you can improve the amount of information you can remember.

It doesn’t always have to be related to completing tasks though. Here’s a good example of chunking from The Unconscious Consumer:

They’ve changed the menu from having six options to three, to make it easier to find what you’re looking for and to help reduce cognitive load.

You can also read more about it here.


This is only an introduction to zeigarnik effect, there are plenty more applications of it out there. I strongly suggest reading a couple of the books and articles I’ve mentioned, for an in-depth look into this effect and other similar psychological phenomena.

As designers, we must be careful of taking advantage of these kind of effects, although there is certainly a place for us to use them to enhance customer experiences on our websites and produce more human-focussed forms and applications.

Or, we can just create the next Pokémon Go.

Thanks for reading. If you’re interested in reading a little more on the cross section of psychology and design, have a read on some of the dark arts being used out there in my article on dark patterns 🙂

Also, feel free to drop me a line on Twitter!

Author: Vinny

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