You've probably heard of the 80/20 rule. But do you also know how you can apply it to usability in UX design? I have taken a closer look at some psychological findings and considered them in relation to the user experience.

Psychologists have always tried to understand why people behave the way they do. What motivates us to make certain decisions? Which events are most likely to be remembered? As a designer, you can also benefit from their findings. I have summarized some well-known rules in relation to product and UX design here.

Occam's Razor or "law of thrift"

In its original form, the law states something like: "Entities should not be multiplied unnecessarily." Over time, however, the original meaning of this rule has been reinforced somewhat through frequent citation, application and further development and has thus developed into the so-called "law of parsimony".

All applications should be kept as simple as possible. If two approaches are available for an entity, both of which say exactly the same thing, then the simpler variant should always be chosen.

How can you apply this to UX design?

The term "simple" often leads to misinterpretations here. Let's take a look at the following graphic. Is the drawing that looks the simplest actually the one that makes it easiest for your users?

This only applies if nothing goes wrong. However, we must always expect that users will not be able to log in without problems. For example, there may not yet be an account or the login data may have been lost.

In this case, the middle drawing would be the simpler approach. But perhaps you have found out through a target group analysis that most of your users have a Google account? Then the third approach is the right one. Because here you save your users from having to enter email and passwords. By allowing them to use a known account, you save them valuable time.

Zeigarnik effect

This approach comes from Bluma Zeigarnik. She was a Russian psychologist in the early 1900's. Her research showed that people of all demographics are more likely to remember unfinished tasks than finished ones.

How can you apply this to UX design?

This effect has two sides. You can use it to entice your visitors to consume more of your content. For example, instead of a full headline, you can simply present a teaser. This will arouse your users' curiosity to consume more of your content.

However, it has a negative effect on the usability of your website if an interaction cannot be completed.

This can happen, for example, if there are technical difficulties so that forms or orders cannot be sent. Or if there is no feedback after visitors have signed up for a newsletter.

However, this rule is also often used to make users do something they don't actually want to do. This is often used when a certain amount of time has already been invested in a process (such as filling out a multi-page form or installing an app), only to find out, for example, that registration is required or that something needs to be purchased in order to continue.

Goal Gradient Hypothesis

This is also about tasks and the time that has already been invested in completing them. According to this thesis, we tend to want to complete a task in which we have already invested a certain amount of time rather than abandon it. It also states that we become faster as we approach the end.

How can you apply this to UX design?

This knowledge is primarily of interest together with the Zeigarnik effect. It therefore makes sense to build up a sequence with simple tasks first. You should save the more complex tasks until the end. So that your users know that the task will soon be finished, you should always display an indicator that shows where the person is in the process. This can be integrated for all processes, such as completing a purchase, subscribing to a newsletter or registering.

Serial position effect

This effect was discovered by Hermann Ebbinghaus, a German psychologist. During his countless researches on the subject of memory, he discovered that we remember the first and last things in a series best.

How can you apply this to UX design?

Checklists or lists of any kind should be designed in such a way that the most important points are at the beginning and at the end. 

Even with long drop-down menus, you should never forget that users do not remember all the content. Price comparisons, as in the example below, benefit from this effect. The first and last prices are the most memorable.

Peak End Rule

Similar to the serial position effect, what counts here is what we see or feel last. This principle explores the fact that we base our subjective memory mainly on two things: How we feel during an extreme moment and at the end of an experience. An extreme moment describes a moment that stands out from the rest. So if you go to a restaurant and have a delicious starter and main course, but the dessert is bad, you are less likely to remember the restaurant well.

The special thing about this phenomenon is that we find it difficult to draw an average value from the overall experience. Our perception is always influenced by these two extremes.

How can you apply this to UX design?

The moment that stands out from the others is often a particularly negative or particularly positive event. Users often experience positive events when something surprising happens. This could be an innovative way of saving time when filling out forms. Or a relaxing animation when finishing a task.

In contrast, frustrating moments are more memorable than moments in which everything went well but nothing special happened.

Aesthetic Usability Effect

This effect describes the fact that we also attribute functioning usability to a good design.

A website that is attractively designed must also be easy to use. 

Visitors to your website will forgive you some usability problems as long as the design of your website appeals to them. However, this only works for minor usability errors. Even a good design won't save a website that fundamentally doesn't work.

In product design, this can even go so far that end consumers prefer a visually appealing product to one that has better features. In extreme cases, excellent design can lead to us building an emotional bond with the product, as we often experience with cars.

Visitors to Forsstudio will be happy to forgive the odd usability error on this pleasantly designed website.

Pareto principle or 20/80 rule

You've probably heard that, for example, 20 percent of your work generates 80 percent of your income. This rule can be applied to quite a few things in life. It says that 20 percent of an event accounts for 80 percent of its output. But you have to be careful, because the figures can of course vary in different areas. There is no guarantee that these figures will always be the same.

How can you apply this to UX design?

Find out which smaller area a large part of your target group spends their time on your website. Instead of redesigning your entire site, you can focus your time and manpower on the most important part of your website. The same applies to e-commerce products. Which 20 percent of your products are purchased by 80 percent of your customers? Place them in such a way that they are easily accessible. Use usability tests to check whether your target group can easily access your bestsellers.

From Restorff effect

During a study in 1933, Hedwig von Restorff discovered that the human brain is most likely to remember the one element in a series that stands out from the others. This can be of a visual nature, but also in terms of content.

How can you apply this to UX design?

In the Otterdev example, the contact button stands out the most from the series of menu items. Here we see several rules combined. The button is the last element in a sequence and is also visually different. Visitors to this website will remember how they can get in touch here. The other points are more likely to be forgotten.

In the following examples, one of the elements stands out from the others and is therefore more likely to be remembered. The meaningful differentiation also works. In the second illustration, it means that customers are more likely to remember "Photography" than one of the other services. However, it assumes that there is a background knowledge of these topics. Users must be able to recognize that the content stands out from the others.

Would you like to find out more about user experience rules?

You can find these and other rules under Law of UX .