Laws of UX¶

Status: emerging
Last updated: 2026-06-02
Sources: Lawsofux.Pdf
Tags: [ux-design, design-principles, heuristics, psychology, usability, human-centered-design, ethics, overview]

Summary¶

Laws of UX (Yablonski, 2024) translates established findings from perception, memory, and decision psychology into practitioner heuristics for interface design. It organises ten named "laws", each stated as a principle, traced to its psychological origin, and illustrated with interface examples, plus closing chapters on applying the principles and on the ethics of using psychology in design. This article is the overview and entry point for the book in this knowledge base; each law has its own dedicated article (linked below) so that further sources on a given topic can accrue there. The book is a synthesis rather than primary research: its value here is as a bridge between the cognitive foundations already held (Working Memory Capacity, Information Processing, Selection And Control Of Action, Perceptual Organization) and applied interface work (Usability And User Experience).

Body¶

Context¶

Yablonski (2024), in the second edition of Laws of UX: Using Psychology to Design Better Products & Services, argues that understanding the psychology behind user behaviour is the single most valuable non-design skill a designer can have, because designs fail when they force users to work against how people perceive and process the world (PDF pp. 9–22, orig. preface – p. 2). The book is structured as ten short chapters, one per "law", each following a fixed pattern — the principle, its origins, interface examples, a technique, a key consideration, and a conclusion — followed by chapters on applying the principles and on ethics. Within this knowledge base the book sits at the boundary between theory and practice, restating cognitive constructs developed elsewhere in the corpus and connecting them to interface guidance. The preface gives a short lineage of the field — Gestalt psychology, the wartime human-factors work of Fitts and Chapanis, human–computer interaction at Xerox PARC, and Norman's coining of "user experience" — that overlaps the history in Human Factors Ergonomics Discipline (PDF pp. 9–16, orig. preface). This overview article also holds the book's two closing chapters; the ten laws are compiled as separate articles.

Key Points¶

The book presents ten laws, each compiled as its own article in this knowledge base:

Jakobs Law — users prefer a product to work like the others they already know; design to existing mental models (PDF pp. 23–34, orig. pp. 3–14).
Fitts Law — time to acquire a target is a function of its size and distance; size and place interactive elements accordingly (PDF pp. 35–46, orig. pp. 15–26).
Millers Law — about 7 ± 2 items in working memory; chunk information rather than enforcing a count (PDF pp. 49–58, orig. pp. 29–38).
Hicks Law — decision time rises with the number and complexity of choices; reduce and stage choices (PDF pp. 59–70, orig. pp. 39–50).
Postels Law — be conservative in what you do, liberal in what you accept; tolerate varied input, give consistent output (PDF pp. 73–84, orig. pp. 53–64).
Peak End Rule — experiences are judged by their peak and end; design memorable highs and positive endings (PDF pp. 85–96, orig. pp. 65–76).
Aesthetic Usability Effect — attractive design is perceived as more usable, and forgives minor flaws (PDF pp. 99–112, orig. pp. 79–92).
Von Restorff Effect — the element that differs is best remembered; use contrast to mark importance (PDF pp. 113–124, orig. pp. 93–104).
Teslers Law — every system has irreducible complexity; the design should absorb it, not the user (PDF pp. 127–138, orig. pp. 107–118).
Doherty Threshold — productivity soars when response time is under ~400 ms; keep feedback near-instant (PDF pp. 139–150, orig. pp. 119–130).

The final two chapters, held in this overview, turn from principles to practice and ethics. Yablonski sets out how to internalise the laws and translate them into explicit, team-aligned design principles that guide decisions (PDF pp. 151–158, orig. pp. 131–138). The closing chapter argues that using psychology to shape behaviour carries responsibility: the same principles that aid usability can be turned into dark patterns that exploit users, and designers must weigh that power against user interests (PDF pp. 159–173, orig. pp. 139–153). This ethical thread connects to the trust and manipulation concerns raised in Cybersecurity Privacy And Trust and Human Centered Design Of Ai.

Conclusion¶

Yablonski (2024) concludes that good user experience comes from designing within the constraints of human perception, memory, and decision making rather than expecting users to adapt to the interface. The ten laws are offered not as rigid rules but as a shared vocabulary and a practical framework: they make psychological constraints explicit so teams can reason about them, articulate their own design principles, and apply them responsibly. For this knowledge base the book is a synthesis layer that links the cognitive-foundations articles to concrete interface guidance; the per-law articles carry the detail and are where further sources on each topic should be added.

References¶

Yablonski, J. (2024) Laws of UX: Using Psychology to Design Better Products & Services. 2nd edn. Sebastopol, CA: O'Reilly Media. yablonski2024lawsux

Open Questions¶

Where do the book's heuristics oversimplify the underlying science? Miller's law in particular is presented as 7 ± 2, which the primary literature has since revised (see Working Memory Capacity, Millers Law).
How should the ethics chapter's treatment of dark patterns be reconciled with the trust and persuasion material in Cybersecurity Privacy And Trust and Human Centered Design Of Ai?
Do the applying-principles and ethics chapters warrant their own articles if further sources on design ethics or design-principle frameworks are added?