The laws of UX are a guiding set of principles and best practices for UX, UI, and product designers. Steeped in psychology, they help us to understand how people perceive and interact with our products—allowing us to make better design choices.
The laws of UX can be divided into four main categories:
- Heuristics
- Gestalt principles
- Cognitive bias
- Principles
In this post, we explain all 21 UX laws and provide an actionable key takeaway for each.
Are you ready to level up your UX? Let’s go!
The laws of UX: heuristics
In psychology, heuristics are mental shortcuts that we use to make decisions and solve problems quickly and efficiently. These mental shortcuts allow us to make sense of the world around us without stopping to process and analyse every single piece of information we receive.
The following UX laws are steeped in heuristics, and they impact how we navigate and perceive different products and experiences.
1. Aesthetic-Usability Effect
The Aesthetic-Usability Effect states that users tend to perceive aesthetically pleasing designs as more usable.
So, even if there are usability issues within your design, they may go unnoticed—or be more easily forgiven—if the design looks great.
That doesn’t mean that you should prioritise aesthetics over usability, but it does emphasise that UX and UI design go hand-in-hand: they both play a crucial role in creating delightful user experiences.
The takeaway: Ensure that your designs are both flawlessly functional and aesthetically pleasing.
2. Fitts’s Law
Fitts’s Law considers how quickly and easily a user can reach a particular target (for example, a button) in order to interact with it.
Named after psychologist Paul Fitts, this UX law describes the relationship between the size and distance of a target (e.g. a button) and the time it takes the user to reach the target.
It’s expressed using an equation which calculates the “Index of Difficulty” (ID)—that is, how difficult it is for the user to get from a particular starting point to the desired target.
In simple terms, bigger and closer touch targets are quicker and easier to access.
The takeaway: Consider Fitts’s Law when determining the size and position of important interactive elements. Make sure that touch targets (such as buttons and menu items) are large enough for users to select them with ease, and that they’re positioned in a convenient, easily accessible location on the screen.
3. Goal-Gradient Effect
The Goal-Gradient Effect states that the closer a user gets to completing a task, the more motivated they are—and the faster they work—to complete it.
This is a UX law that many of us can relate to. If a goal feels like it’s within reach—if we feel close to the finish line—we’re more inclined to just get on and get it done. Our perceived proximity to the end goal makes it feel more achievable and less overwhelming.
The same goes for digital products and experiences. Imagine the task of filling out a survey. If you’ve been answering questions for what feels like an eternity, with no indication as to when the survey might end, you’ll probably feel like giving up at some point.
But, if the survey platform keeps you updated on your progress and lets you know that you’re nearing the end, you’ll be more inclined to see it through.
The takeaway: Provide users with clear progress or task status visibility to keep them motivated—such as a progress bar or some well-placed microcopy. For example: “You’re almost there! Just three more questions to go.”
4. Hick’s Law
According to Hick’s Law, the more options a user is presented with, and the more complex those options are, the harder it is to make a decision.
It’s like eating out at a restaurant. When you’ve got a menu comprising five different types of cuisine and thirty options for each, choosing what you want feels practically impossible!
The same goes for design. If you want to create an experience that feels intuitive, make it easy for the user to decide what action to take. Don’t give them too many options—and, if a particular process is inherently long and complex, break it down into smaller, more manageable steps.
The takeaway: Fewer options will make it quicker and easier for users to make decisions and complete their desired tasks. Where possible, keep options to a minimum. You can also guide users in their decision-making by highlighting recommended options.
5. Jakob’s Law
Jakob’s Law is all about familiarity. Users expect websites (and other digital products) to be designed in a way that’s consistent with others they’ve used in the past.
Even when using an app or visiting a website for the very first time, you usually have some ingrained knowledge of how it’ll work. For example, we just know that the house icon will take us to the homepage—or, when using dating apps, that swiping left will “pass” on a profile while swiping right is a virtual “thumbs up”.
Now imagine the chaos that would ensue if designers went against these expectations. Imagine signing up for a new dating app and swiping left and right, only to realise that left now actually means “like” and right now means “pass”. Very confusing and counter-intuitive!
Jakob’s Law says that we should design in a way that aligns with people’s existing mental models—a user’s set of assumptions, beliefs, and expectations regarding how certain things work. This ensures an intuitive, smooth, and user-friendly experience.
The takeaway: Don’t try to reinvent the wheel. Leverage users’ existing mental models to inform your designs—for example, place menus at the top of the page or to the left-hand side, use familiar icons, and implement familiar interactions such as swiping left/right on a photo gallery or scrolling to move down the page.
6. Miller’s Law
Miller’s Law states that the average person can only hold 7 items in their working memory, plus or minus 2.
In UX and UI design, you want to avoid overloading the user’s working memory. In other words, minimise the cognitive load—or the mental effort—required for the user to interact with your product.
Present information in meaningful, manageable chunks. If you’re building an ecommerce website, you might limit the number of products shown at one time. If you’re designing a blog, you might present articles in horizontal blocks of three.
The takeaway: Aim for clear, concise, and clutter-free designs and you’ll automatically reduce the cognitive load placed on the user. Break content down into manageable chunks, prioritising the most important information first.
7. Parkinson’s Law
According to Parkinson’s Law, a task will expand to fill the time allotted for its completion.
In other words, if you set aside a certain amount of time to complete a particular task, you’ll usually use up all of that time—even if you don’t really need it. If you’re allotted one hour to complete a five-minute job, Parkinson’s Law says that you’ll still use the whole hour.
Designers can use Parkinson’s Law to their advantage by making certain tasks even quicker and more efficient than the user expects. For example, if the user expects to spend one minute creating a new account, anything you can do to speed that process up will enhance the user experience.
The takeaway: Design tasks and processes so that they’re even quicker than the user expects. Simplify forms, use features like autofill, and give the user an estimate for how long a particular process should take.
The laws of UX: Gestalt principles
The Gestalt principles are a set of psychological principles that consider how humans tend to perceive and make sense of visual information. In UX and UI, we can use the Gestalt principles to design and arrange different elements according to how we want the user to group and interpret them. The next five UX laws on our list are all derived from Gestalt psychology.
8. Law of Common Region
The Law of Common Region states that, when elements are positioned together in the same area—i.e. when they share a common region within a boundary—the user perceives those elements as belonging together.
Consider this screenshot taken from The UX Design Institute blog:
When you perceive this page, you can instantly ascertain—without really thinking about it—what elements belong together. You know that each image, article title, date, and reading time belongs to a particular blog article. That’s because you perceive them as sharing a common region.
Designers can use borders, spacing, and colour to create common regions and group elements together, making it easier for the user to understand the relationship between different elements on the page. This, in turn, facilitates navigation and usability.
The takeaway: Group elements together logically and emphasise these groupings according to the Law of Common Region. Use borders, spacing, colour, and shading to define different regions on the page.
9. Law of Proximity
According to the Law of Proximity, items or elements that are positioned close together are perceived as belonging to the same group.
This is similar to the Law of Common Region. When we see visual elements in close proximity to one another, we assume they have something in common—that they belong to a particular group of elements or that they all function in a similar way.
The Law of Proximity enables the user to quickly deduce the relationship between different elements and groups, making it easier to navigate the interface.
The takeaway: Use the Law of Proximity to signal which elements belong together. For example, if you’re designing a form, place form labels and their corresponding input fields close together so the user knows exactly what information to enter where.
10. Law of Prägnanz
The Law of Prägnanz states that when we perceive complex or ambiguous imagery, we automatically interpret it in the simplest way possible.
It’s as if the brain carries out an automatic conversion, turning a complex image into something much simpler and therefore easier to comprehend. This is the brain’s way of reducing the cognitive effort required to interpret the image.
So how does this relate to UX and UI design?
If you want to design products and experiences that are easy and efficient for the user, you ideally want to reduce the amount of cognitive effort required. One way you can do that is by favouring simple, straightforward shapes like squares, circles, and rectangles.
The takeaway: Bear in mind that more complex, ambiguous images require more effort to comprehend. Opt for simpler shapes and imagery, especially for important elements such as call-to-action buttons.
11. Law of Similarity
According to the Law of Similarity, elements that look similar will naturally be perceived as a related group.
This speaks to the power of consistency throughout a product or user interface. A classic example is the styling of hyperlinked text. In a Google Doc, hyperlinking a piece of text will turn it blue. This builds a connection in the reader’s mind—that all blue text has something in common; i.e. it contains a hyperlink.
Another example is the distinction between header text and body text. If you’re styling the text on a website, you’ll probably use a large, bold font for header text—and maybe even a different colour—compared to smaller, lighter body text.
The takeaway: Use colour, shape, and size to differentiate between different elements and build meaningful connections between similar elements. For example, links should all be styled the same to signal that they share the same functionality.
12. Law of Uniform Connectedness
The Law of Uniform Connectedness states that when elements appear to be connected in terms of their visual appearance, we perceive them as being part of a related group—unlike visually dissimilar elements that appear to have no connection.
Just like the Law of Similarity, designers can play into the Law of Uniform Connectedness to help users understand and navigate an interface. Elements can be connected by colour, lines, frames, or even arrows. These visual cues tell the user that those elements have something in common and belong to the same group.
The takeaway: Use colour, borders, shapes, or visual connectors such as arrows to visually group different elements and help your users to understand the interface.
The laws of UX: cognitive bias
Some UX laws are based on cognitive bias—our natural human tendency to interpret information and make assumptions based on previous experiences and preferences. If we understand the cognitive biases at play, we can design products that meet the users’ expectations and feel more intuitive. Here are four UX laws shaped by cognitive bias.
13. Peak-End Rule
The Peak-End Rule suggests that people don’t judge an experience based on all the different moments along the way—rather, they judge it primarily based on how they felt at the peak of the experience and at the end.
While every step in the user’s journey should be smooth and hiccup-free, designers can enhance the user’s overall perception of the experience by paying special attention to the peak and the end.
The peak is a particularly key or defining moment in the journey—for example, the user completing a task or achieving a goal. The end is the final step or interaction they have.
You can enhance these moments with memorable microcopy, a delightful animation, or some kind of unexpected surprise (perhaps a discount code or a gift, depending on the product and the experience in question).
The takeaway: Identify key moments within the user journey and ensure that they’re particularly positive and memorable.
14. Serial Position Effect
According to the Serial Position Effect, users are most likely to remember the first and last items in a sequence.
Whether left to right or top to bottom, think about the order in which people will perceive your designs. With the Serial Position Effect in mind, place the most important elements where they’ll be encountered first and last—for example, to the far left and to the far right of the navigation menu, or at the top and the bottom of the page.
This applies to both visual and written content—anything the user encounters when interacting with a product or completing a particular task.
The takeaway: Keep this UX law in mind when defining your product’s information architecture and visual hierarchy. The most important elements should appear first and last in the sequence, with less critical information in the middle.
15. Von Restorff Effect
The Von Restorff Effect states that when we’re presented with multiple similar elements, we’re most likely to remember the element that differs even slightly from the rest.
This UX law is also known as the Isolation Effect, and it describes our tendency to be drawn to things that stand out. Imagine you’re presented with a piece of paper with fifteen circles drawn on it. They’re all the same size, but fourteen are blue and one is red. You’ll likely be drawn to the red one, right?
You can apply this principle to draw the user’s attention to important elements such as CTA buttons or headings. This, in turn, guides them towards particular actions or influences how they perceive the content on the page.
The takeaway: Use shapes, negative space, colour, and typography to help important elements stand out.
16. Zeigarnik Effect
According to the Zeigarnik Effect, uncompleted or interrupted tasks stick in people’s memories more than completed tasks.
This UX law is named after psychologist and psychiatrist Bluma Wulfovna Zeigarnik who discovered that starting a particular task creates cognitive tension in the user.
When cognitive tension is present, the user is able to recall specific information related to that task. But, once the task is complete, the cognitive tension dissipates—as does the person’s ability to recall task-related information.
In UX terms, the Zeigarnik Effect can be used to create task-related cognitive tension which can help to keep users engaged and encourage them to return to a particular task.
Consider the example of a fitness tracker that counts your daily steps. If your goal is to take 6,000 steps a day, a progress bar will remind you that you haven’t yet reached your goal—in other words, it’ll keep you cognitively engaged. Once you’ve hit your 6,000 steps, you can relax (both physically and mentally!)
The takeaway: Provide the user with visual indicators of incomplete tasks. This will build task-related tension and encourage them to return to, and engage with, the task at hand.
The laws of UX: additional principles
Last but not least, there are some additional principles that complete our 21 laws of UX. Let’s explore those now.
17. Doherty Threshold
According to the Doherty Threshold, users expect an instant response when interacting with a computer—instant being 400 milliseconds or less.
This is a UX law we can all relate to. If you’re interacting with a website, you expect feedback on your actions. For example, if you’re shopping online and you click “Add to basket”, you want clear confirmation that the action was successful—and you want it fast.
The Doherty Threshold states that users should receive feedback within 400 milliseconds if they are to perceive the experience as smooth and productive.
The takeaway: Reward every user action or interaction with clear and instant feedback. Even if the process itself takes longer, provide the user with a progress bar or a timer so they know that something’s in motion.
18. Occam’s Razor
Occam’s Razor is a problem-solving principle that suggests that the simplest solution is often the best solution.
As a rule of thumb, every element in your design should serve a purpose. If it doesn’t add any specific value for the user or help to enhance the user experience in some way, remove it.
Occam’s Razor helps UX designers to prioritise usability, functionality, and clarity, removing unnecessary clutter and complexity. It’s similar to the KISS principle which reminds us to “Keep it simple, stupid!”
The takeaway: Consider your design complete when there’s nothing more you could possibly remove without compromising functionality.
19. Pareto Principle
The Pareto Principle is an 80/20 rule that says that around 80% of the effects come from 20% of the causes.
Although the Pareto Principle derives from economics, it’s also useful for UX design. Because not all features or design elements will hold equal weight in shaping the user experience, the Pareto Principle encourages designers to focus their efforts on the areas that will have the biggest impact.
If you’re looking to improve your website, for example, you don’t need to redesign it from top to bottom. Rather, you can focus on one or two aspects (the 20%) that will make the most difference (80%).
The takeaway: Conduct research and testing to identify the features and elements that have the biggest impact on the user experience—and focus most of your efforts there.
20. Postel’s Law
Postel’s Law states that you should be flexible in terms of what you accept from your users while limiting what you ask of them.
The easiest way to explain Postel’s Law is with the example of a form. When designing a form, you want to make it as straightforward as possible for the user to fill out. One way to do that is to be liberal in terms of what answers and input you’ll accept.
For example: imagine one question on your form asks the user to enter their country of residence and they enter “UK”. If you’re designing with Postel’s Law in mind, you’ll accept this answer, as well as other possible variations such as “United Kingdom”.
This flexible approach makes the experience hassle-free for the user. At the same time, you want to limit what you ask of them—so, when designing your form, you’ll only include questions that are really and truly necessary.
The takeaway: Anticipate the different inputs your users might provide or the actions they might take within a given scenario, and design to accommodate them.
21. Tesler’s Law
According to Tesler’s Law, every system has a certain degree of complexity that cannot be reduced.
UX design is all about creating smooth, intuitive, hassle-free experiences. Often, this favours ease, simplicity, and clarity. However, Tesler’s Law reminds us that simplification has its limits. Every system has a degree of intrinsic complexity that can only be boiled down to a certain point.
Oversimplification beyond that point compromises the system or product’s functionality—which results in a bad user experience. Ultimately, not all complications or complexities can be designed away.
The takeaway: Aim for utmost simplicity in the user experience, but don’t seek to simplify the system itself to the detriment of functionality.
How to use the laws of UX
I know, I know—that’s a mighty long list of UX laws! But don’t get too hung up on remembering all of them, all of the time. As you develop your UX and UI design skills, you’ll naturally adhere to these principles without even thinking about it.
Most of the laws of UX can be boiled down to the following:
- Prioritise simplicity and clarity
- Think about your users’ mental models and how they expect your product or system to behave
- Limit the cognitive burden on your users wherever possible
If you enjoyed learning the laws of UX, continue with these fundamental principles all designers should know and these 8 dos and don’ts of UI design.
