When users hesitate, click the wrong thing, or abandon a flow altogether, something’s off. More often than not, a UX law is being quietly broken.
This guide walks you through the laws of UX that every designer and developer should be aware of. You’ll discover:
- What they are and when they matter
- How to apply them without turning your product into a rulebook
The takeaway? You don’t need to follow every single principle of UX design. Only the ones that fix friction and move you faster, with fewer guesses.
And if you want help finding that friction in the first place, Marvin makes it easy to identify where users get stuck and which UX law might resolve the issue.
Create a free Marvin account and use it to go from raw research to real design improvements. Faster, clearer, and backed by user behavior.
What Are UX Laws?
UX laws are guidelines based on psychology that help you design better products. They typically:
- Describe how people behave when interacting with systems (their habits, expectations, and limitations)
- Guide you to cater to their behaviors, so you design with those patterns in mind (instead of fighting them)
Fitts’ Law in UX design, for example, shows that the time to reach a button depends on its size and distance. That’s why tiny tap targets on mobile devices drive users up the wall. Or why your checkout button shouldn’t be floating in a far-off corner.
Keep in mind, though, that UX design laws aren’t set in stone. They guide your thinking, but you still need to test and adjust based on your users and context.
Origins and History of UX Laws
The UX laws as we now know and use started in science, not design. Most come from psychology, human-computer interaction (HCI), and behavioral studies going back to the mid-20th century.
Back then, researchers wanted to know:
- How people make decisions
- How fast they react
- What slows them down
Hick’s Law came from a 1952 paper. It showed that the more options you offer, the longer it takes someone to make a decision.
Miller’s Law followed a few years later. It found that people can only hold about seven things in memory at once.
These laws emerged as essential clues about how the brain works. As digital products gained popularity, they proved to be ideal for interface design.
In the 1980s and 1990s, Don Norman, Jakob Nielsen, and other usability experts connected those studies to screens. They turned academic findings into practical guidance that designers could finally use to make science-backed choices.
From there, UX laws began to appear in books, guidelines, and checklists.
Then came Jon Yablonski’s Laws of UX, which turned the abstract laws into colorful, clickable, easy-to-use tools. The website was built as a repository for UX principles and best practices. To this day, it remains a go-to resource for designers.
The Role of UX Laws in Modern AI Interfaces
AI is changing design interfaces and the way users interact with products. And still, people want the same things:
- Clarity
- Control
- Experiences that feel easy, familiar, and fair
That’s why UX laws still matter. They’re anchors for human behavior, which hasn’t evolved nearly as fast as technology.
But AI systems aren’t traditional interfaces. You’re not just guiding users through screens. You’re designing systems that interpret intent, respond in real time, and handle open-ended prompts.
That means the old rules don’t always fit as they are. You need to rethink how UX laws apply in chat, voice, and predictive interfaces. Some get harder to apply. Others take on new meaning.
Take Fitts’ Law, which links the time to interact with something to how big and close it is. What happens when there’s no visible target at all, just a chat prompt or voice input? The interaction isn’t about hitting a button anymore. It’s about the system understanding what the user meant.
At Marvin, we think this shift is exciting, even though it’s not simple.
That’s why we brought together AWS design leader Maria Papaleo and our cofounder, Prayag Narula. In a recent webinar, we explored how UX rules are evolving in the age of AI.
Here’s a snippet of what we covered:
- Why a law like Jakob’s still matters but needs rethinking in AI-first, multimodal interfaces
- How Hick’s Law plays out when infinite choice creates new types of cognitive overload
- What Fitts’ Law looks like when your “target” is an AI’s ability to read your mind
- Why “Glass Box UX” is becoming the new gold standard for trust and explainability
- How designing for intent, not just tasks, will reshape your role as a product designer
Want the breakdown of how to adapt the core principles when designing modern interfaces? Get access to the full on-demand webinar, “Why the Laws of UX Still Matter when Designing with AI.”
12 Laws of UX Every Designer Should Know
One of the best-known collections that encompasses UX laws is Jon Yablonski’s Laws of UX. This website compiles up to 30 different principles, classic laws (Hick’s, Fitt’s, etc.), and effects (Von Restorff Effect, Aesthetic-Usability Effect, etc.).
The good news is you don’t need to memorize them all. Only the ones that come up repeatedly when you’re building flows, testing prototypes, or reviewing research.
Here are the 12 UX laws you should have in your toolkit to begin with:
1. Hick’s Law
When users face too many choices, they freeze or stall.
That’s why you need to reduce clutter and simplify decisions.
Use this law when designing navigation, filters, or prompts. Remember that input fields can overwhelm quickly. To lower cognitive load, guide users toward focused and helpful actions.
2. Fitts Law
The time to reach a target depends on its size and distance.
Therefore:
- Big, close buttons feel faster and easier to use.
- Small or spaced-out actions slow people down.
This law is particularly relevant in mobile UI, including tap targets and toolbars.
In AI overlays, you’ll want to make frequent actions easy to reach.
3. Jakob’s Law
Users carry expectations from other tools. They don’t read your docs; they expect things to just work.
To cater to these expectations, match common patterns across platforms and devices.
If your chatbot works differently from others, explain it. Familiarity lowers friction, especially when AI behavior might feel uncertain or unexpected.
4. Miller’s Law UX
People can only hold about seven chunks of information in working memory.
Group related items and break steps into small pieces, ideally fewer than seven. Equally important, avoid long sentences or crowded layouts.
In AI-generated interfaces, limit the scope of suggestions or output. The simpler the screen, the faster users move forward.
5. Law of Prägnanz
Users prefer simple, organized visuals.
When things look confusing, they are difficult to scan and feel harder to use. To help the brain out, use alignment, spacing, and grouping that create order.
In AI dashboards or assistant panels, pay even more attention to structure. Clutter kills clarity.
6. The Von Restorff Effect
Things that stand out are easier to remember.
Keep this effect in mind when you want to draw attention and launch a CTA, warning, or highlight.
Make it stand out by adding color, shape, or animation, but don’t overdo it. If everything pops, nothing does.
In AI interfaces, highlight key suggestions or recommended next steps.
7. Tesler’s Law UX
Every product has complexity. The trick is deciding who handles it, you or the user?
Good design absorbs complexity so users don’t have to. To do so, you can:
- Set smart defaults
- Hide advanced settings
- Pre-fill forms
AI can help here by predicting, summarizing, or reducing effort behind the scenes.
8. The Peak-End Rule
People remember the best part and the ending of an experience.
Use that wisely, making sure the last step in a flow feels smooth, not awkward. Also, make sure to confirm success and celebrate wins. In AI interfaces, this translates into:
- Showing why a result was great
- Explaining why it ended where it did
9. The Serial Position Effect
Items at the beginning and end of a list are most remembered.
Put important stuff first or last, not buried in the middle.
This effect applies to menus, steps, or even AI-generated recommendations. Order can shape what users recall, click, or ignore.
10. The Doherty Threshold
Fast responses keep people in flow. If your system replies in under 400ms, users stay engaged.
The problem is that AI systems often take longer to process. To simulate a faster pace, display partial results and progressive loading.
Also, when time is tight, feedback matters more than perfection.
11. The Aesthetic-Usability Effect
Users forgive flaws in beautiful products. Clean visuals build trust.
This doesn’t mean you should let looks mask problems. Test often to spot and fix what’s broken.
This polishing is all the more important with AI tools. Here, users are already unsure of how things work, so the UI must feel solid. Even if the backend’s still learning.
12. Postel’s Law UX
Be flexible in what you accept, but strict in what you return.
In UX, this means:
- Allowing a range of user input
- Keeping your output consistent and easy to understand
A user might type “cancel my sub,” “end subscription,” or even “stop paying.” Your system should understand all three and respond the same way. That’s being flexible in what you accept.
But what you return must be clear and structured: “Your subscription will be canceled at the end of the billing cycle.” Not a brief “Okay” or a long-winded AI paragraph.
This is critical in AI tools, where inputs are unpredictable. People will enter anything from shorthand to rambling prompts. Your system should handle the noise and return something clean, specific, and useful.
Translating UX Laws into Real-World Design Decisions
The UX laws aren’t meant to sit in a Figma file with a fancy quote and no follow-through. They should actively shape how you structure flows, place buttons, organize content, and prioritize features.
Consider the following tips to make the leap from principle to product:
Start with the Friction, Not the Law
Each law maps to a specific type of struggle. By spotting an issue, you’ll know what law you need to implement.
First, clarify what appears to be the problem. Are they hesitating, skipping a step, or giving up halfway?
Then, reverse-engineer the behavior.
If they’re overwhelmed by choices, that could point to Hick’s Law.
If they’re struggling to tap the right button, you should check against Fitts’ Law.
And if they’re confused about where to start because the design is unfamiliar, Jakob’s Law might be at play.
Frame Research with UX Laws
When you observe confusing behavior in testing, ask yourself:
What’s the mental load here? Are users misjudging what’s clickable? Are they failing to remember key info?
Then, you can use laws to shape follow-up questions.
Maybe users keep skipping a form field. You might ask, “Was that field visually grouped with the rest?” (Prägnanz).
Or perhaps they hesitate when making a choice. Try, “Did you feel like there were too many options to pick from?” (Hick’s Law).
Have Developers Build the Laws into the Experience
Some laws are code-dependent by nature.
Take the Doherty Threshold, which states that if the system responds within 400ms, users remain in flow. That speed comes from backend performance, not pixels. If it lags, users lose trust, regardless of how sleek the design appears.
When you understand these laws, you can speak the language of your development team.
You’ll be able to say, “Let’s pre-load this response to hit the Doherty threshold.” Or “Can we validate this input softly, not block the user immediately?”
Adapt the Laws for AI Interfaces
AI adds unpredictability. The interface is less rigid and the outcomes more varied. But that only makes UX laws more important, not less.
Laws like Hick’s, Jakob’s, and the emerging Glass Box Law (discover it in our webinar) are key here. Use them to add structure and clarity, and simplify the output from the AI. Highlight what matters and build trust through feedback and transparency.
Frequently Asked Questions (FAQs)
Before you move on to implementation, consider these UX laws FAQs:
How Many Types of UX Laws Are There?
The UX laws are less about labels and more about supporting UX best practices and better design decisions. While there aren’t strict “types,” you’ll see UX laws grouped into categories that:
- Describe how people make choices
- Explain how memory works
- Clarify how users form expectations
You’ll also see UX design principles, heuristics, and cognitive effects lumped in.
What’s the Difference Between UX Heuristics and UX Laws?
UX laws describe how people make decisions, process information, or respond to feedback. They explain why something is likely to work or fail.
Heuristics tell you what to do, design-wise: “show system status” or “make interactive elements obvious.” They reflect what tends to work across many products, even though formal studies have not proven them.
In practice, you’ll use:
- The law to understand why a user behaves a certain way
- The heuristic to design an interface that aligns with that behavior
Is It Necessary to Follow All UX Laws in Every Project?
No, not every law is applicable to every project. It’s acceptable to deviate from these laws, provided you have a clear, user-centric reason for doing so. Otherwise, they’ll help you spot issues, make tradeoffs, and build smarter. A single well-applied law can save you hours of redesign.
What Tools Can Help Implement UX Principles?
You don’t need special software to follow UX laws, but some tools will particularly help you:
- Figma makes visual patterns easier to spot
- Qualitative usability testing tools help you validate them
- Marvin enables you to connect the dots when running user research
Book a free demo to see how Marvin tags behavior, tracks insights, and surfaces design patterns in one place.
Conclusion
The laws of UX design are working principles grounded in human behavior. Even in AI-powered products, they’re just as relevant today as ever for:
- Making sense of messy user behavior
- Justifying design decisions
- Guiding product choices that feel intuitive, not forced
That said, it’s easy to assume UX laws are the foundation of every good design. But they’re not. Research is.
As you observe users and spot friction in their experience, you’ll understand what UX law to implement.
If you need help uncovering user friction and applying UX principles with purpose, create a free Marvin account.
Marvin helps you capture user experiences, tag them, and connect insights to the right UX principle. All so you can fix the real issue fast.
