Preface

This book had its origins in what felt at the time like the most arduous point of my design career, while I was working on a very challenging client project. From the beginning, there were several indications that it would be an exciting albeit difficult project: a relatively short timeline and a somewhat unfamiliar space, but a well-known brand and the chance to help design something that’d be seen by many across the world. These have always been my favorite kinds of projects because they are the ones that offer the most opportunity to learn and grow, which I’ve always striven to do. But this project was somewhat unique in one specific way: I was being asked to justify a number of design decisions to project stakeholders, without any data to support them. Normally, when you have quantitative or qualitative data available to draw upon, this a pretty straightforward task—but in this case the data wasn’t available, so the process of justifying the decisions would have to be a little different. How do you validate initial designs without any proof that there is a need to change the existing designs to begin with? As you can imagine, design reviews quickly became a matter of subjectivity and personal bias, resulting in designs that were more difficult to validate.

Then it occurred to me: psychology, which provides a deeper understanding of the human mind, could be helpful in these circumstances. I quickly became immersed in the rich and expansive field of behavioral and cognitive psychology, and found myself reading through countless research papers and articles in order to find empirical evidence that supported the design decisions I was making. This research became quite useful in convincing project stakeholders to move in the proposed design direction, and I felt as if I had found a treasure trove of knowledge that would ultimately make me a better designer. There was only one problem: finding good reference material online quickly turned into an exhausting task. Searches led me to a vast array of academic papers, scientific research, and the occasional article in the popular press—none of which felt directly relatable to my work as a designer. I was looking for a designer-friendly resource that just wasn’t available online, or at least not in the form I wanted it. Eventually I decided to dive in and produce the resource I was looking for myself, resulting in the creation of a website called Laws of UX (Figure P-1). This passion project became a way for me to both learn and document what I was discovering at this time.

Screenshot of the Laws of UX website, circa 2020

The absence of quantitative or qualitative data related to the project I was working on led me to look elsewhere, and what I discovered regarding the intersection of psychology and user experience (UX) design has been nothing short of transformative for my practice. While such data, where available, remains valuable, my foray into psychology helped form a solid foundation for my work grounded in an understanding of how people behave, and why. This book is an expansion of the Laws of UX website that focuses on various psychological principles and concepts that I’ve found particularly useful as a designer.

Why I Wrote This Book

I wrote this book in order to make complex laws of psychology accessible to more designers—specifically designers that don’t have background knowledge in psychology or behavioral science. The intersection of psychology and UX design has become an increasingly relevant topic in an era when design roles are having an ever-stronger impact within organizations. Along with a growing focus on design, there has been an increase in debate around which additional skills designers should learn, if any, to increase their value and contribution. Should designers code, write, or understand business? These skills are all valuable, but perhaps not essential. However, I would argue that every designer should learn the fundamentals of psychology.

As humans, we have an underlying “blueprint” for how we perceive and process the world around us, and the study of psychology helps us decipher this blueprint. Designers can use this knowledge to build more intuitive, human-centered products and experiences. Instead of forcing users to adapt to the design of a product or experience, we can use some key principles from psychology as a guide for designing in a way that is adapted to people. This is the fundamental basis of human-centered design, and it is the foundation of this book.

But knowing where to start can be a challenge. Which principles from psychology are useful? What are some examples of these principles at work? There’s an endless list of laws and theories that occupy this space, but there are a few that I’ve found particularly helpful and widely applicable. In this book, I explore these concepts and present some examples of how they are effectively leveraged by products and experiences we interact with every day.

Who This Book Is For

This book is for anyone that wishes to improve their design craft, learn more about the intersection of psychology and design, or simply explore why people react to good design the way they do. It’s aimed at designers who want to have a better understanding of psychology and how it impacts and overlaps with the work we do. It’s for professional and aspiring designers alike: anyone who seeks to understand how the overall user experience is affected by an understanding of human perception and mental processes. While the book is specifically focused on digital design as opposed to the more traditional mediums of graphic or industrial design, the information it contains is broadly applicable to anyone responsible for shaping user experience. I should also mention that it isn’t intended to be a comprehensive resource, but rather an accessible introduction to the psychology fundamentals that have a direct influence on design and how people process and interact with the interfaces we create. It’s full of examples and intended to be easily read and referenced by designers who wish to incorporate this information into their daily work.

This book will also be relevant to anyone that seeks to understand the business value of good design and why good design is transformative for businesses and organizations. The field of UX design has grown and expanded into new areas thanks to the increase in investment by companies looking to gain a competitive advantage. With this new interest has come the expectation that products and services should be well designed, and simply having a website or mobile application is no longer enough. Companies must ensure their websites and applications, and any other digital experiences they offer, are helpful, effective, and well designed. In order to achieve this, designers can, I believe, use psychology as a guide, enabling them to design for how people actually perceive, process, and interact not only with digital interfaces but also with the world.

What’s in This Book

Chapter 1, Jakob’s Law: Users spend most of their time on other sites, and they prefer your site to work the same way as all the other sites they already know.
Chapter 2, Fitts’s Law: The time to acquire a target is a function of the distance to and size of the target.
Chapter 3, Hick’s Law: The time it takes to make a decision increases with the number and complexity of choices available.
Chapter 4, Miller’s Law: The average person can keep only 7 (± 2) items in their working memory.
Chapter 5, Postel’s Law: Be conservative in what you do, be liberal in what you accept from others.
Chapter 6, Peak–End Rule: People judge an experience largely based on how they felt at its peak and at its end, rather than on the total sum or average of every moment of the experience.
Chapter 7, Aesthetic–Usability Effect: Users often perceive aesthetically pleasing design as design that’s more usable.
Chapter 8, von Restorff Effect: When multiple similar objects are present, the one that differs from the rest is most likely to be remembered.
Chapter 9, Tesler’s Law: Tesler’s law, also known as the law of conservation and complexity, states that for any system there is a certain amount of complexity that cannot be reduced.
Chapter 10, Doherty Threshold: Productivity soars when a computer and its users interact at a pace (<400 ms) that ensures that neither has to wait on the other.
Chapter 11, With Power Comes Responsibility: Here, we take a closer look at the implications of using psychology to create more intuitive products and experiences.
Chapter 12, Applying Psychological Principles in Design: This chapter considers ways designers can internalize and apply the psychological principles we’ve looked at in this book and then articulate them through principles that relate back to the goals and priorities of their team.

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Acknowledgments

First and foremost, I must acknowledge and thank my wife Kristen, whose love and support have been both endless and critical in so many ways—without her this book would not have been possible. Thanks also to my mom, the strongest person I know and the one who encouraged, supported, and enabled me to follow my dreams to begin with, and to James Rollins, a man I’m forever grateful to have in my life and the lives of my family. I’d like to also acknowledge all of my design colleagues who helped with the book in some way or another: in no particular order, Jonathan Patterson and Ross Legacy for always-on-point design advice and feedback; Xtian Miller for the encouragement, feedback, and words of wisdom; and Jim and Lindsey Rampton, Dave Thackery, Mark Michael Koscierzynski, Amy Stoddard, Boris Crowther, Trevor Anulewicz, Clemens Conrad, and countless others for the support and encouragement. I also owe a debt of gratitude to all the individuals involved in the project that inspired this book, who therefore directly influenced its creation. I’d like to thank Jessica Haberman, who saw the potential in me to become an author and encouraged me to begin the endeavor of writing this book. And finally, I owe Angela Rufino a great deal of gratitude for all the advice, patience, and feedback throughout the process.