A Brief Guide to the Laws of UX for Product Managersby@peculiar
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1,112 reads

A Brief Guide to the Laws of UX for Product Managers

by Peculiar Ediomo-AbasiJuly 17th, 2022
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The Laws of UX is a hack for any user-driven development team to focus on giving users maximum experience with a product. This article will walk you through the 21 laws and how you can apply them in real-life products. The first part focuses on the laws of UX around heuristics. The laws are categorized under the categories of 'Aesthetic Usability' and 'Gradient Gradient' Law. The time to acquire a target is a function of the distance to and size of the target, Fitt’s Law.
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The Laws of UX is a hack for any user-driven development team to focus on giving users maximum experience with a product—Knowing their needs and playing it into how a product is built goes a long way in making them happy.

In today’s world of high demand for digital innovation, product managers have become more passionate about being the voice of the user and are adopting UX within their product management day-to-day life. You can too!

This article will walk you through the 21 Laws of UX and how you can apply them in real-life products. I know reading the 21 laws and their examples at a go is a lot, so I have made this article a series so you can enjoy every bit of it.

This first part focuses on the laws of UX around heuristics.

What is Heuristics in UX?

According to the Oxford dictionary, heuristics means enabling someone to discover or learn something for themselves. In product design, this definition translates into having set down guidelines to ensure usability, and the ability to identify problems and solutions related to the design interface.

The Laws of UX categorized under heuristics help us understand the cognitive and behavioral ways that humans generally interact with products. Let’s delve in!

1. Aesthetic Usability Effect

Users often perceive aesthetically pleasing design as design that’s more usable

This law refers to the idea that if users find an interface visually appealing, then they are likely to be more forgiving of minor issues with the usability. This is mainly because users are strongly influenced by the beauty of any given interface and have the tendency to perceive attractive products as more usable.

The aesthetics of a product can mask usability issues while the interface is being tested for usability. If the development team somehow knows of these usability issues, they can mark time to fix it. But an obvious delay in fixing it can sometimes be very costly.

An example: In 2016, a US company with $120 million in venture funding introduced Juicero, a first-at-home cold-press juicing system that was fancy but totally useless.

Image from

A lot of customers bought the product as it promised an easy way to turn cut-up fruits and vegetables into juice. But their frustrations began when they realized the following:

  • The $400 internet-enabled juice machine required really strong internet to work.
  • The device could not work without the mobile app.
  • And there was no real need for the device as the juice packs that the device was to cold-press could be squeezed by hand.

According to Bloomberg, in 2017 Juicero customers were offered a refund, and that marked the end of the product.

2. Fitt’s Law

The time to acquire a target is a function of the distance to and size of the target.

On a user interface, touch areas should be conveniently large enough for users to reach them with ease and accurately touch them. The smaller the target size and longer the distance, the longer it would take for a user to touch them.

For example, when a call-to-action button on a mobile app is obviously positioned around a user’s thumb area, the user would be able to tap them quickly. This could mean making the buttons larger, and spacing them such that the user can tap them adequately.

On the flip side, Fitt’s law can be applied on purpose to make something difficult for a user to select, like a “Delete Account” button.

An uncommon, dicey, or irreversible UI element can be made hard for users to click on to reduce costly mistakes.

3. The Goal-Gradient Effect

The tendency to approach a goal increases with proximity to the goal.

On Duolingo, each language lesson has a mini progress bar that makes learners eager to finish up a lesson. This is called the Goal-Gradient Effect.

Progress is motivating, even the illusion of it. Duolingo makes really good use of this knowledge to encourage users to learn a new language, reinforce their learnings, and have revisions after a while of finishing up a lesson.

Linkedin is another great platform that utilizes the Goal-Gradient Effect. They encourage their users to complete their profile by persuading them to move from the Beginner level, Intermediate, Advanced, Expert, up to the All-Star level.

4. Hick’s Law

The time it takes to make a decision increases with the number and complexity of choices.

The more options available to a person, the longer it will take for them to make a decision on which to choose. Too many choices lead to decision paralysis and as a result, a frustrating experience for users.

Image from 17Seven

5. Jakob’s Law

Users spend most of their time on other sites. This means that users prefer your site to work the same way as all the other sites they already know.

Invariably, when users land on your site they come sentimental expecting to see your design align with their mental models.

The use of familiar patterns fosters trust and safety in your users and is recommended when designing your product so that your users can navigate through it easily. There is no need to reinvent the wheel, just leverage existing mental models—Buttons should be rectangular, not triangular, and so be it.

Image from

6. Miller’s Law

The average person can only keep 7 (plus or minus 2) items in their working memory.

Studies show that the number of objects an average person can hold in their working memory is about seven. If given about 15 words to memorize, you are likely to remember about 5 to 9 words reasonably. Which is 7 ± 2 words.

Phone numbers and credit card numbers are formatted in chunks for the same reason of making it easy to call out or memorize, else it would just be a long string of digits that’s hard to remember.

For example, (+234) 7061 062 092 is easier to read than +2347061062092. This process of grouping information is known as chunking.

7. Parkinson’s Law

Any task will inflate until all of the available time is spent.

When there is a stipulated time for a task to be carried out, increasing the length of time does not necessarily mean that you would perform the task better. Parkinson’s law simply goes to say that work will expand to fill the time allotted for its completion.

For a given task, humans will naturally feel the need to take all the time given to complete a task even if it doesn’t require that much time. This is why aiding users to finish a task in time is recommended. You can employ the use of smart defaults and predictions where necessary, to reduce cognitive load.

In Conclusion,

Understanding why users act the way they do allows you to play the laws of UX to your product advantage, and use it to improve your user’s experience.

These laws of UX can be applied together where necessary and sometimes interwoven, like Hick’s law and Miller’s Law. The major difference between these laws is that Hick’s law focuses on the time and effort required, while Miller’s law addresses memorability and focus, even though both influence the user’s speed.

This is part 1 of this article series on the Laws of UX. The link to part 2 would be added here when it is ready. Thanks for reading to the end!

Feel free to connect with me on LinkedIn.