Laws of UX

Have you ever interacted with an app or website that just felt right—like it understood exactly what you needed? In Laws of UX: Using Psychology to Design Better Products & Services, Jon Yablonski argues that this sense of intuitive ease is no accident. It’s the result of applying timeless psychological principles to modern design problems. Yablonski’s central claim is that great design is human design: products that succeed most aren’t just visually appealing or innovative—they are built on a deep understanding of how people think, feel, and behave.

He grounds his argument in twelve core “laws” of user experience, each derived from cognitive and behavioral psychology. These include findings from classic research—like Miller’s Law and Hick’s Law—and insights from contemporary cognitive science about attention, perception, and decision-making. Together, they form a toolkit for crafting efficient, delightful, and ethically responsible digital experiences.

Why Psychology Matters in Design

Yablonski opens with a personal story: early in his career, he was asked to justify design decisions without any user data. He turned to psychology to understand how people navigate complexity and to find empirical grounding for choices about layouts, interactions, and feedback. What he discovered became the foundation of Laws of UX—a framework that makes psychological science accessible to designers who might not have formal training in cognitive theory. Just as engineers rely on physical laws, Yablonski argues, designers can rely on psychological ones to predict human reactions.

The Core Framework

The book introduces twelve major laws. Each chapter explores a principle through clear explanations, historical origins, and real-world examples. For example, Jakob’s Law explains that users bring mental models from other sites; Fitts’s Law quantifies how size and distance affect clickability; and Hick’s Law reveals how too many options paralyze decision-making. Later laws—like the Peak-End Rule and the Aesthetic–Usability Effect—illustrate the emotional side of experience. Yablonski then moves beyond individual techniques to question the ethics of persuasion in Chapter 11 (“With Power Comes Responsibility”), urging designers to wield behavioral insights carefully.

The Human Blueprint of Experience

According to Yablonski, every human shares a perceptual and cognitive “blueprint.” Understanding this blueprint helps designers craft experiences that fit how people really operate rather than how we wish they would. This approach, known as human-centered design, reframes UX as empathy in practice: the job is not to make users adapt to systems, but to adapt systems to users.

Each law connects psychological theory to design application. Rather than just theory, Yablonski shows how Google, Apple, Mailchimp, and Tesla translate these insights into interfaces that “just work.” Whether it’s a button positioned for the thumb’s reach (Fitts’s Law) or an onboarding process that reveals complexity gradually (Hick’s Law), psychology becomes a practical guide for crafting elegant simplicity.

Ethics and Accountability

Yablonski doesn’t stop at usability. He warns that the same psychological levers that make software addictive can also manipulate users. Drawing from behavioral economist B.F. Skinner’s operant conditioning, he examines how “variable rewards” drive compulsive engagement (think Instagram likes or infinite scroll). While companies may celebrate this as “engagement,” Yablonski urges designers to slow down, diversify their teams, and consider whom their choices serve. In this sense, Laws of UX reads as both a field manual and a moral compass.

Why This Book Matters

In today’s world—where technology pervades everything from healthcare to entertainment—the need for ethical, psychologically grounded design has never been greater. You don’t need to be a psychologist to apply these principles; you just need curiosity about how humans tick. Yablonski’s work equips you to design experiences that are both effective and empathetic, blending science, creativity, and conscience in equal measure. His message is clear: the best design doesn’t trick you into clicking—it helps you think, move, and feel with ease. That’s the true law of UX.

Imagine opening an app only to find everything in a new place—menu icons scrambled, search bar hidden. You’d likely close it in frustration. Jakob’s Law, named after usability expert Jakob Nielsen, explains why: users spend most of their time on other sites and expect yours to work the same way. Yablonski argues that familiarity saves cognitive energy. When we align design with users’ pre-existing mental models—the frameworks built from previous experiences—interfaces feel instantly understandable.

Mental Models and Familiarity

Mental models are the mind’s shortcuts; they predict how a system should behave. Designers can reduce friction by matching their structures to users’ expectations. Yablonski uses the example of form controls—toggles, radio buttons, and sliders—all modeled on their physical predecessors. These metaphors help users instantly grasp function without needing instructions. Misalignment, by contrast, leads to confusion. The 2018 Snapchat redesign ignored its users’ expectations and merged stories and chats into one space, resulting in outrage and mass defections to Instagram.

Balancing Sameness and Innovation

Should everything look the same? Yablonski warns against both extremes. While standard patterns promote efficiency, blind imitation leads to pervasive sameness. He points to Google’s approach—introducing redesigns gradually, allowing users to opt in to new UIs (like Gmail’s Material Design). This strategy lets users learn at their own pace, easing mental model updates without alienation. In short: conform when it helps, innovate when it truly improves the experience.

Knowing the User: Personas as Tools

To align mental models, designers must know their users intimately. Yablonski advocates using personas—fictional but evidence-based profiles summarizing demographics, motivations, and pain points. Personas keep development grounded in real human behavior rather than abstract ‘user’ assumptions. They remind teams to design not for themselves but for the people they serve.

“Familiarity is the invisible hand guiding usability. The best interfaces feel learned before you touch them.” —Jon Yablonski

Jakob’s Law teaches you to prioritize the path of least resistance: when users encounter something familiar, their brain processes it faster, freeing focus for their goals. To apply it, begin with common conventions—then earn the right to diverge. Design, as Yablonski puts it, should never make someone relearn what they already know unless it’s genuinely worth it.

Every tap, click, or swipe asks users to move their hands with precision. Fitts’s Law measures the speed and effort required to do so. Originally a 1954 psychological model for physical motion, it states that the time to reach a target depends on its size and distance. In UX, this means: large, nearby buttons feel faster. Yablonski translates this principle to digital ergonomics, showing how even milliseconds of friction scale into frustration for millions of users.

Sizing, Spacing, and Placement

Yablonski distills decades of ergonomic research into three design imperatives: make touch targets large enough, separate them sufficiently, and place them within easy reach. He references industry guidelines—Apple’s 44×44 pt, Google’s 48×48 dp, WCAG’s 44×44 px. He also notes that the average fingertip is 16–20 mm wide, showing how people physically interact with technology. Screens differ by context: desktop precision contrasts with thumb-based smartphone use, where central-screen “thumb zones” enable the most comfortable tapping (as shown by researcher Steven Hoober).

Designing for Human Limits

From LinkedIn’s cramped acceptance buttons to Tesla’s spacious on-screen controls, Fitts’s Law helps diagnose usability successes and failures. Apple’s Reachability feature, which brings the top of the screen within thumb range, epitomizes design empathy—it translates physical insight into effortless experience. Yablonski’s lesson: respect anatomy as much as aesthetics. Interfaces should accommodate humans, not the other way around.

In practice, this law reinforces a truth echoed by Don Norman (The Design of Everyday Things): usability is tactile. When buttons are too small or too far away, you’re not just violating a design rule—you’re violating human physiology. Fitts’s Law reminds you that speed, ease, and delight start at your fingertips.

When faced with too many menu choices, you hesitate. That pause is Hick’s Law in action. Developed by psychologists William Edmund Hick and Ray Hyman, it shows that the time to make a decision increases logarithmically with the number and complexity of available options. Yablonski applies this to digital design: the busier the interface, the slower (and less satisfying) the user experience.

Reducing Cognitive Load

Cognitive load refers to the mental effort required to process information. High load drains focus, leading to abandonment or error. Yablonski urges designers to reduce noise—through hierarchy, progressive disclosure, and clear call-to-actions. Google Search exemplifies this: when you first land, only one action is obvious—search. Only after input do filters appear. Slack’s onboarding bot follows the same logic: hiding complexity until mastery builds gradually.

Simplify but Don’t Oversimplify

Yablonski cautions that simplification can backfire when taken too far. Icons without labels, for instance, reduce visible clutter but increase ambiguity. Real clarity comes from context and cues—pairing symbols with text ensures understanding. This echoes Steve Krug’s mantra from Don’t Make Me Think: users shouldn’t guess what something means.

Hick’s Law teaches purposeful restraint. As Yablonski puts it, remove every element that doesn’t help users reach their goal, but no more. Too many options overwhelm; too few disorient. Simplicity, then, is not minimalism—it’s meaningful reduction.

In the 1950s, psychologist George Miller discovered the magical number seven—the average number of items most people can hold in short-term memory. Yablonski points out that designers often misapply this, citing it to justify arbitrary limits on navigation items. The real takeaway, he insists, is not the number—it’s about chunking: organizing information into digestible groups so users process and recall it easily.

Chunking in Digital Design

Chunking turns complexity into pattern. A U.S. phone number divided into 3-3-4 digits is far easier to remember than a ten-digit string. Websites achieve similar clarity through headlines, whitespace, and modular cards. Yablonski shows how Bloomberg and Nike group related content visually so scanning feels natural. Chunking doesn’t mean dumbing down—it means structuring for recognition rather than recall.

Memory and Meaning

Humans aren’t databases; our attention fluctuates with context and familiarity. Miller’s Law reminds us that short-term memory capacity varies by person and situation. Effective UX design respects these limits by guiding attention, not overloading it. By chunking, you create rhythm and predictability—the cognitive equivalent of breathing room.

In essence, Miller’s Law is about kindness to the human brain. Group information logically, vary hierarchy, and space elements generously. Your users won’t remember every detail—but they’ll remember how easy it was to understand.

Postel’s Law—originally a guideline for internet communication—translates in UX as: be conservative in what you do, but liberal in what you accept. Jon Postel’s insight was about computer protocols, but Yablonski applies it to human interaction. Interfaces should be robust, forgiving, and inclusive, capable of handling the wide variability of human behavior.

Forgiving Design

Yablonski describes forms as a prime example. Instead of rejecting imperfect input (“invalid format”), flexible systems adapt—auto-correcting, pre-filling known data, or expanding input tolerance. Apple’s Face ID epitomizes this principle by reducing authentication friction: no more passwords, just recognition. Similarly, responsive web design and progressive enhancement ensure content gracefully adapts to screen size, bandwidth, and device type.

Design Resilience

Postel’s Law also shapes how teams build resilient systems. Designing for language expansion, accessibility, and user customization prepares products for diverse audiences. Amazon, for example, anticipates font-size changes and reorganizes layouts dynamically. IBM’s carbon design system, Salesforce’s Lightning, and Shopify’s Polaris frameworks all operationalize this principle—accepting countless contributors while outputting predictable consistency.

Ultimately, Postel’s Law reframes inclusivity as robustness. Every unpredictable user input—broken URLs, typos, slow connections—isn’t failure but opportunity. Designs that adapt, not punish, are the ones people trust.

When users remember your product, they don’t recall the whole journey—just its emotional peaks and how it ended. This is the Peak–End Rule, discovered by psychologist Daniel Kahneman. Yablonski applies it to user experience: the most intense and final moments define whether people will return, recommend, or uninstall.

Crafting Positive Peaks

Mailchimp exemplifies this principle through its playful design. When you send a campaign—a high-stress action—it shows its mascot nervously sweating, then high-fiving you afterward. This emotional choreography transforms anxiety into relief, imprinting joy at a critical moment. Uber, too, softens wait times with animations and progress transparency, turning irritation into reassurance.

Mapping Emotion

Yablonski recommends journey mapping to identify these pivotal moments. By charting user actions, mindsets, and emotions, teams can amplify highs, mitigate lows, and end experiences gracefully. Even errors become opportunities—humorous 404 pages or gentle recovery messages convert frustration into forgiveness.

The Peak–End Rule reminds you that memory is emotional, not logical. Focus your polish on the key peaks and the finish line. People might forget the middle—but they’ll definitely remember how you made them feel.

Yablonski’s penultimate chapter is a sobering one: while psychological laws can make design intuitive, they can also make it addictive. He explores the moral dimension of influence in an age of persuasive technology. Drawing on B.F. Skinner’s operant conditioning, he shows how social platforms exploit behavioral loops—likes, endless feeds, autoplay—to keep people hooked.

Technology as Behavior Shaper

Through examples from casinos to smartphones, Yablonski draws parallels between slot machines and pull-to-refresh gestures. Many features, born as usability improvements, became psychological traps. Infinite scroll, variable notifications, and default settings subtly shape habits while masquerading as neutral design. When convenience turns compulsive, he argues, designers share responsibility for social harm.

The Ethics Imperative

Citing research linking smartphone use to reduced cognitive capacity and rising youth depression, Yablonski urges teams to redefine success metrics beyond engagement. He recommends fostering diverse design teams (to expose blind spots), considering edge cases rather than only the happy path, and blending quantitative data with real human feedback. Ethical awareness, he writes, is now a core UX skill.

The call is clear: slow down, be intentional, and design for wellbeing. Power without empathy leads to manipulation; psychology without ethics breeds addiction. Real progress means creating products that help humans thrive, not merely click.

In his final chapter, Yablonski shifts from theory to application. How can teams bake psychological insights into daily workflow? His answer: through culture, principles, and visibility. Just as architecture has foundational rules of space and proportion, UX teams need guiding principles rooted in human cognition.

Building Awareness

Yablonski shares stories of teams printing Laws of UX posters and hanging them around their offices. Visibility, he says, fosters shared vocabulary. Weekly “show-and-tells” allow designers to internalize lessons and discuss real examples. These rituals turn abstract theory into lived culture.

Design Principles as North Stars

He outlines a framework for codifying team principles: brainstorm freely, converge on themes, refine phrasing, and advocate widely. Crucially, each principle should connect to a psychological law—linking a goal (“clarity over abundance of choice”) to an observation (Hick’s Law) and actionable rules (e.g., “limit visible options to three”). This triad makes design reasoning explicit and defensible.

Yablonski concludes that maturity in design teams isn’t just about process—it’s about shared understanding of human nature. Embedding psychology transforms design from guessing to guiding.

Ultimately, applying these laws isn’t about memorizing formulas, but adopting a mindset: curiosity, empathy, and evidence over ego. When teams align around how people truly behave, innovation becomes second nature—and humanity remains at the heart of every pixel.