Summary
Laws of UX is Jon Yablonski's collection of ten principles drawn from psychology and cognitive science that bear directly on user interface design. Originally a website (lawsofux.com) launched in 2018, the book version published by O'Reilly in 2020 expands each principle with context, examples, and design guidance. It is a short, dense book aimed at practitioners who want to ground their design decisions in human cognitive tendencies rather than taste or convention.
The principles Yablonski covers include Hick's Law (more choices mean slower decisions — relevant to navigation and feature design), Fitts's Law (targets should be sized and positioned proportionally to how often they're used), the Aesthetic-Usability Effect (attractive interfaces are perceived as more usable, sometimes falsely), the Peak-End Rule (users remember the peak moment and the final moment of an experience disproportionately), and the Von Restorff Effect (things that differ from their surroundings are remembered). None of these are original to Yablonski — they come from psychology research spanning decades — but his contribution is to apply them specifically to digital product design and to show, with concrete examples, how violation of each principle produces recognizable failures.
The book's ambition is explicitly ethical as well as practical. Yablonski is aware that the same principles used to make interfaces usable can be used to make them manipulative — dark patterns exploit cognitive tendencies just as surely as good design works with them. He dedicates a chapter to the ethics of design, arguing that practitioners have a professional obligation to understand the power they wield and to use it responsibly. This makes the book more honest than most UX writing, which tends to treat manipulation and design as entirely separate concerns.
The brevity is a feature, not a bug: each law is explained, illustrated, and reflected on within about twenty pages. Practitioners can absorb the full framework in an afternoon and return to individual sections when working on specific problems. The book's weakness is that the coverage is necessarily selective — there are many more psychological principles relevant to design than ten — and the depth of application is limited. Yablonski is clear that this is an introduction, not a comprehensive framework.
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Key takeaways
- 1.
Hick's Law: the time to make a decision increases logarithmically with the number of options. Menus, onboarding flows, and feature sets should reduce choices, not maximize them.
- 2.
Fitts's Law: the time to reach a target depends on its distance and size. The most frequently used controls should be the largest and most accessible — a principle violated constantly in mobile design.
- 3.
The Aesthetic-Usability Effect means attractive interfaces are perceived as easier to use even when they aren't. Beauty is not separate from function; it shapes how users evaluate function.
- 4.
The Peak-End Rule means users remember the most intense moment and the final moment of an experience, not the average. The quality of the peak and the ending matters more than the middle.
- 5.
The Von Restorff Effect: isolated or contrasting elements are remembered better. This works for calls to action; it also explains why too many visual 'priorities' produce none.
- 6.
Cognitive load is finite. Every unnecessary element or decision consumes attention that the user needed for something else. Simplicity is a cognitive service, not just an aesthetic preference.
- 7.
The same psychological principles that power good design also power dark patterns. Understanding the principles means understanding both how to help users and how they're being exploited elsewhere.
- 8.
Mental models — users' expectations based on prior experience — should shape interface behavior more than interface logic. What a user expects a thing to do matters as much as what it's technically capable of.
Discussion questions
Use these on your own, with a book club, or as chat starters in Superbook.
- 1.
Hick's Law says more choices slow decisions. Think about a digital product you use that violates this. What would you cut, and what would you expect to improve?
- 2.
The Aesthetic-Usability Effect means people perceive attractive things as more usable. Is that a cognitive bias to be corrected or a reasonable heuristic to design with?
- 3.
The Peak-End Rule says people remember the peak and the end of an experience, not the average. What are the implications for how you design onboarding, checkout flows, or support interactions?
- 4.
Yablonski includes a chapter on design ethics, arguing that practitioners who know these principles have a responsibility to use them for good. Do you think that responsibility is taken seriously in the field? What would change if it were?
- 5.
Dark patterns — interfaces designed to exploit cognitive tendencies against the user's interests — are widely used. Have you encountered them? What specific law or principle were they exploiting?
- 6.
Fitts's Law is about the physical relationship between target size and position and the effort required to reach it. What in the products you use most frequently is clearly sized and positioned for the designer's convenience rather than yours?
- 7.
Mental models shape how users interpret interfaces. Think of a product that violated your mental model in a way that cost you time or caused an error. Whose fault was it?
- 8.
The book selects ten laws. What psychological principles relevant to design do you think are missing from the list?
- 9.
Yablonski argues that understanding cognitive science is essential for designers. Is that the designer's responsibility, or is it better handled by researchers who feed findings to designers?
- 10.
The book was a website before it was a book. Does the format of a book change how you engage with reference material like this, compared to a web resource you can search?
- 11.
Which of the ten laws would have the most impact if applied consistently across the digital products you use every day? What would change?
Themes
Frequently asked questions
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What is Laws of UX about?
Ten principles from cognitive psychology and human factors research — including Hick's Law, Fitts's Law, and the Peak-End Rule — applied specifically to digital interface design. Each law explains a predictable pattern in human perception or behavior and shows what it means for design decisions.
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Is this a beginner's book or for experienced designers?
Both. The concepts are introduced clearly enough for beginners, and experienced designers often find it useful as a reference and a framework for justifying design decisions to non-designers. The brevity means it doesn't overwhelm either audience.
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How long does it take to read?
Two to three hours for a cover-to-cover reading. It's designed as a reference as much as a narrative — most readers read it once and then return to individual sections when working on specific problems.
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Does this replace reading the original psychology research?
No — it's a practical introduction, not a comprehensive review. Yablonski points to the research but doesn't go deep into methodology or limitations. Readers who want more rigor should follow the cited sources.
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Is the ethics chapter worth reading?
Yes, and it's more direct than most UX writing on the subject. Yablonski doesn't pretend the principles are neutral — he explains how they're used in dark patterns and argues that designers bear responsibility for that. It's short but honest.
