Laws of UX

Laws of UX Plot Summary

Introduction

Have you ever wondered why some digital products feel intuitive while others leave you frustrated? The secret lies not in visual aesthetics alone, but in how well these designs align with our innate psychological patterns. At the intersection of psychology and user experience design exists a framework of principles that explains how humans perceive, process, and interact with digital interfaces. This framework illuminates why we find certain designs more usable than others, how our attention and memory limitations affect our interactions with technology, and what makes us trust some interfaces while abandoning others. By understanding these psychological principles, designers can create experiences that feel natural and frictionless rather than forcing users to adapt to unintuitive systems. These laws aren't merely theoretical constructs but practical guidelines grounded in decades of cognitive and behavioral research, offering a structured approach to designing products that truly serve human needs and capabilities.

Chapter 1: Understanding Mental Models and User Expectations

Jakob's Law states that users spend most of their time on other sites and prefer your site to work the same way as those they already know. This principle captures a fundamental truth about human cognition: we build mental models based on our experiences and then apply those models to new situations. When an interface aligns with our existing mental models, we can immediately be productive instead of first having to learn how it works. Mental models are what we think we know about a system, especially about how it works. Whether it's a website or a physical checkout line, we form models of how systems work and then apply them to new but similar situations. Good user experiences emerge when the design of a product aligns with users' mental models, enabling them to transfer knowledge from previous experiences without needing to learn a new system. The strength of Jakob's Law lies in its recognition of the cumulative effect of saved mental effort. The less cognitive energy users spend learning an interface, the more they can dedicate to achieving their objectives. This creates a lower cognitive load, which is essential for a positive user experience. Take ecommerce websites as an example—by conforming to users' expectations about selecting products, adding them to virtual carts, and checking out, designers ensure users can apply accumulated knowledge from previous shopping experiences. However, Jakob's Law doesn't advocate for sameness in the sense that every product should be identical. Rather, it suggests that designers should consider common conventions built around existing mental models when appropriate. When all websites follow completely different designs, users would need to learn how each one works before being productive, creating frustration and wasted effort. The principle reminds us that familiarity helps users accomplish tasks efficiently. It's wise to begin with common patterns and conventions, only departing from them when a compelling reason exists to improve the core user experience. Innovation is valuable, but it shouldn't come at the expense of usability. The goal is to leverage users' existing knowledge while still creating distinctive experiences that meet specific needs.

Chapter 2: Optimizing Interface Elements for User Interaction

Fitts's Law establishes that the time required to move to a target is a function of the distance to and size of the target. In practical terms, this means larger targets that are closer to the user's current position are faster and easier to select. This principle, while seemingly obvious, has profound implications for interface design across all devices and platforms. At its core, Fitts's Law helps us understand three critical aspects of interactive design. First, touch targets should be sufficiently large for users to accurately select them without frustration. Second, these targets need adequate spacing between them to prevent accidental selection of adjacent elements. Third, important interactive elements should be placed in easily accessible areas of the interface. The applications of this principle are visible everywhere in well-designed interfaces. Consider form text labels that are associated with input fields—by making both the label and input field selectable, designers effectively expand the touch target area, making interactions more forgiving. Similarly, the placement of form submission buttons close to the last input field minimizes the distance users must travel to complete their task, reducing both time and effort. Context matters significantly when applying Fitts's Law. On mobile devices, for instance, the accessibility of screen areas varies dramatically depending on how the device is held. Research shows that accuracy is highest in the center of smartphone screens, where users naturally focus their attention. This insight has led to features like Apple's Reachability, which brings content from the top of the screen down to more accessible areas for one-handed use. The principle extends beyond digital interfaces to all interactive systems. In vehicle displays like Tesla's Model 3, where driver attention is a critical safety concern, Fitts's Law guides the spacing and sizing of controls to minimize distraction and error. By understanding and applying this law, designers create interfaces that work with human physical capabilities rather than against them.

Chapter 3: Managing Cognitive Load and Decision Making

Hick's Law states that the time it takes to make a decision increases with the number and complexity of choices available. This principle directly addresses a fundamental challenge in design: cognitive load, or the mental resources required to use an interface. When users face too many options, they experience decision paralysis, frustration, and often abandon the task altogether. Cognitive load works similarly to computer memory—when too much information exceeds available capacity, performance suffers. Our working memory has limited slots for storing information relevant to the current task. When interfaces demand more mental resources than available, users begin to lose critical information, making tasks more difficult and causing frustration. The principle manifests in countless everyday examples. Consider the evolution of TV remotes—from overwhelming arrays of buttons to streamlined smart TV controllers with minimal options. The complexity hasn't disappeared; it's been transferred to on-screen menus where information can be progressively disclosed and organized into logical categories. This approach respects users' limited cognitive resources while still providing full functionality. Digital products apply Hick's Law through thoughtful constraints and progressive disclosure. Google Search initially presents just a simple search box, only revealing filtering options after you've begun your search. This keeps users focused on the primary task without overwhelming them with secondary choices. Similarly, Slack's onboarding experience introduces features gradually, mimicking how we naturally learn—building upon each previous step rather than overwhelming new users with the platform's full complexity. However, simplification must be balanced against clarity. Oversimplifying interfaces to the point of abstraction can create different problems, particularly when using iconography without text labels. Icons rarely hold universal meaning across different users and contexts. The key is finding the balance between reducing cognitive load and providing sufficient context for users to understand their options and make informed decisions.

Chapter 4: Creating Adaptable Systems and Experiences

Postel's Law, also known as the robustness principle, states: "Be conservative in what you do, be liberal in what you accept from others." In UX design, this translates to creating systems that are flexible and tolerant of varied user input while maintaining reliable and consistent output. This principle acknowledges a fundamental reality: humans don't behave like machines—we're inconsistent, often distracted, and occasionally error-prone. In practical terms, the first half of Postel's Law ("be conservative in what you do") means creating interfaces and systems that are reliable and accessible regardless of device size, feature support, input mechanism, or connection speed. The second half ("be liberal in what you accept") means accepting various forms of user input—whether it's keyboard, touch, voice, or assistive technology—and processing that input meaningfully. The principle manifests in several approaches to modern digital design. Responsive web design embodies Postel's Law by creating interfaces that fluidly adapt to any viewing context, from smartwatches to large desktop screens. Instead of creating separate experiences for different devices, responsive design embraces the inherent flexibility needed to serve content appropriately across countless screen dimensions. Progressive enhancement similarly applies this principle by focusing first on core content and functionality for all users, then layering enhancements for those with more capable browsers or devices. This approach ensures universal access to essential content while providing richer experiences where supported. A simple search box might be enhanced with voice input capabilities only on devices that support voice recognition, without compromising the core functionality. Design systems—collections of reusable components guided by consistent standards—also demonstrate Postel's Law. They must liberally accept diverse input from contributors across disciplines (design, content, code, strategy) while conservatively producing clear, purposeful outputs (guidelines, components, patterns). This balance allows organizations to scale design consistently while accommodating the complexity of enterprise environments. The approach requires anticipating variations in user context. Text in interfaces might expand dramatically when translated to different languages, or users might customize font sizes for accessibility. Resilient designs account for these possibilities rather than breaking under unexpected conditions, creating truly adaptable experiences.

Chapter 5: Leveraging Memory and Perception in Design

The peak-end rule reveals that people judge experiences based primarily on how they felt at their most intense point and at the conclusion, rather than averaging the entire experience. This psychological principle has profound implications for how users remember their interactions with products and services, and whether they're likely to return or recommend them to others. Our memory doesn't work like a comprehensive video recording—instead, it captures representative snapshots, particularly emotionally charged moments. These emotional peaks, whether positive or negative, disproportionately influence our overall impression of an experience. The conclusion of an experience receives similar weight in our memory, creating a recency effect that colors our entire perception. Smart companies capitalize on this psychological pattern by carefully designing emotional peaks and endings. Mailchimp demonstrates this understanding in their email campaign creation process. Sending an email campaign represents a peak emotional moment filled with anticipation and potential anxiety. Mailchimp defuses this tension with their confirmation modal featuring Freddie, their mascot, hovering nervously over a send button, adding humor to a potentially stressful moment. After sending, users receive a satisfying high-five animation that creates a positive ending to the experience. Negative emotional peaks can be equally influential. Wait times, for example, often create frustration that can taint an entire experience. Uber addresses this by applying several psychological techniques to their waiting experience—providing entertainment during idle moments, offering transparency about how arrival times are calculated, and showing clear progress toward the goal of getting a ride. By focusing on perceptions of waiting rather than just the wait itself, they reduce cancellations and prevent negative impressions. Journey mapping serves as an invaluable tool for identifying these emotional peaks throughout an experience. This qualitative exercise visualizes how people use a product by mapping their actions, mindset, and emotions across a timeline. By clearly identifying emotional high and low points, designers can focus their efforts on moments that will most significantly impact users' lasting impressions and their likelihood to return.

Chapter 6: Balancing Complexity and Usability

Tesler's Law, also known as the law of conservation of complexity, states that for any system, there is a certain amount of complexity that cannot be reduced. This principle addresses a fundamental question: who should bear the burden of complexity—the user or the designers and developers? The answer shapes how we approach the design of interfaces and human-computer interactions. The core insight of Tesler's Law is that inherent complexity in any process cannot be eliminated—it can only be shifted. This complexity must be handled either in the user interface or in the underlying system created by designers and developers. The goal of good design is to minimize the complexity faced by users by absorbing as much of it as possible into the system itself. Email systems provide a clear example of this principle in action. Every email requires a sender and recipient—this complexity cannot be eliminated. However, modern email clients reduce this burden by prepopulating the sender field and suggesting recipients based on your contacts or previous emails. The complexity still exists, but it's handled by the system rather than requiring user effort. Gmail takes this further with features like Smart Compose, which uses AI to suggest words and phrases as you type, shifting more complexity away from the user. The checkout process in online shopping demonstrates another application of Tesler's Law. By allowing shipping addresses to inherit information from billing details, or implementing services like Apple Pay that eliminate the need to enter payment information repeatedly, designers reduce complexity for users while shifting it to the development team that must implement these features. Some companies push this principle to remarkable extremes. Amazon Go stores create a checkout-free shopping experience where customers simply walk in, take what they need, and leave. The immense technical complexity involving machine learning, computer vision, and AI creates a seemingly magical experience that feels effortless to customers—a perfect example of complexity being absorbed by the system rather than imposed on users. The challenge for designers lies in finding the right balance. While simplifying interfaces benefits users, oversimplification can lead to abstraction where there's insufficient information for users to make informed decisions. Icons without text labels, for instance, may save space but introduce ambiguity that creates new forms of complexity. Good design doesn't eliminate complexity entirely, but intelligently distributes it to create intuitive, efficient experiences.

Chapter 7: Applying Psychological Principles Responsibly

The psychological principles that guide user experience design represent powerful tools for shaping human behavior. This power comes with significant ethical responsibility, as these same techniques can be employed to manipulate users rather than serve their needs. Understanding both the potential benefits and risks of psychological design principles is essential for ethical practice. Behavioral psychology insights, like those discovered by B.F. Skinner through operant conditioning, can be observed throughout digital products. Variable reward schedules—proven most effective at influencing behavior in Skinner's experiments—appear in features like social media notifications, pull-to-refresh mechanisms, and recommendation algorithms. These techniques can create compulsive usage patterns similar to those observed in gambling, where unpredictable rewards lead to repeated engagement. Other common psychological tactics include infinite loops that remove natural stopping points, social validation mechanisms that trigger dopamine responses, default settings that exploit status quo bias, and friction reduction that encourages specific behaviors. Dark patterns—deceptive techniques that trick users into actions they didn't intend—represent the most problematic application of psychological principles, appearing in thousands of popular websites according to research. The ethical implications become clear when examining unintended consequences. Features like Facebook's "Like" button, originally intended for positive engagement, have been linked to addiction-like behaviors and metrics of self-worth. Research suggests that smartphone presence alone reduces cognitive capacity, while social media use correlates with increased depression and loneliness in young adults. These outcomes were likely unintended by their creators but represent real harm nonetheless. Ethical design requires several shifts in approach. First, designers must think beyond ideal "happy path" scenarios to consider vulnerable users and edge cases. Second, diverse teams bring broader perspectives that help identify potential harms that homogeneous groups might miss. Finally, looking beyond quantitative metrics to qualitative research helps understand how products actually impact users' lives and well-being. The responsibility falls on designers to ensure that psychological principles augment human experiences rather than exploit vulnerabilities. This means slowing down, being intentional about design choices, and continually evaluating whether products are serving users' genuine needs or merely business objectives. The most ethical approach uses psychology to create intuitive experiences that respect users' agency, attention, and well-being.

Summary

The psychological principles of UX design reveal a profound truth: successful digital experiences don't force users to adapt to technology, but rather adapt technology to innate human patterns of perception, cognition, and behavior. By leveraging these laws—from respecting existing mental models to managing cognitive load, from creating memorable moments to thoughtfully distributing complexity—designers can create interfaces that feel intuitive because they align with how our minds naturally work. These principles extend far beyond aesthetic considerations to address fundamental aspects of human psychology that influence our interaction with technology. As digital experiences become increasingly embedded in daily life, the responsible application of these principles becomes not just a design advantage but an ethical imperative. The ultimate measure of design success isn't engagement metrics or conversions, but whether technology truly enhances human capability and well-being by working with our psychology rather than against it.

About Author

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Jon Yablonski

I’m Jon Yablonski, a Senior UX Designer with a passion for designing digital tools that empower people. I’ve had the opportunity to learn and grow from a variety of challenges throughout my career — from e-commerce platforms, mobile apps and internal products to HMI systems within state-of-the-art vehicle platforms. I’m currently helping the world learn from its data as a Senior Product Designer Mixpanel. Previously, I worked on the next generation of in-vehicle digital experiences General Motors.

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