• The Nike+ FuelBand, a wristband that automatically tracks your movement and helps you exercise more (one of a dozen new, wearable computing devices on the market)

  • Nest, a thermostat that learns your home heating schedule, reinforces good energy usage with a simple phone app, and automates saving money on electricity bills

  • GlowCap, a cap for prescription bottles that flashes when it’s time to take medication and automatically reorders the medication online when you need it

  • Clocky, an alarm clock that jumps off your nightstand and rolls around the room, so you can’t turn it off without getting out of bed (Figure 1)

    Clocky, the clock that runs away from you

    Figure 1. Clocky, the clock that runs away from you

  • Barack Obama’s highly successful online volunteer platform that enabled volunteers to call potential voters from home, whenever they had a few minutes to spare (Figure 2)

    Obama’s volunteer mobilization site,, during the 2012 campaign

    Figure 2. Obama’s volunteer mobilization site,, during the 2012 campaign

  • Lift, the habit-building application; 401(k) auto-escalation programs for saving for retirement; and the QuitNow! mobile app to stop smoking with peer support[1]

Each of these products was designed to help individuals take action in their lives. Companies have developed a slew of new and innovative products in this space over the past few years—inspired by behavioral economists like Richard Thaler and psychologists like Daniel Kahneman and BJ Fogg.

This book is about how to design, implement, and test such products. Traditional product design is about building good products—products that work well and people like using. Designing for behavior change is about building products that are both good and behaviorally effectiveproducts that help people change their behavior. The goal is to help people do things that they want to do but have struggled with in the past.

The method I discuss here comes, in large part, from our daily experiences at HelloWallet, where I serve as the head researcher. Over the past few years, we’ve successfully built (and experimentally tested) products that help people take control of their finances—after much trial and error and learning along the way. This method also builds upon the experiences of countless other companies and researchers that we’ve been talking to and sharing notes with about behavior change. So, let’s get started.

What Does It Mean to Design for Behavior Change?

Within the last decade, there has been a tremendous flowering of research in behavioral economics, psychology, and persuasive technology. This research helps us understand how people make decisions in their daily lives, and how those decisions are shaped by people’s prior experiences and their environment. Throughout this book, you’ll see how to methodically and rigorously apply the lessons from psychology and behavioral economics to the practical problems of product design and development.

Applying that literature is the first part of designing for behavior change. The overall process entails four phases, which inform and enhance how we build products (Figure 3):

Designing for behavior change is four stages: start with a core understanding of the mind, discover the right behavior, design the initial product, and then iteratively refine it

Figure 3. Designing for behavior change is four stages: start with a core understanding of the mind, discover the right behavior, design the initial product, and then iteratively refine it

  1. Understand how the mind decides to act and what that means for behavior change.

  2. Discover the right behaviors to change, given your goals and your users’ goals.

  3. Design the product itself around that behavior.

  4. Refine the product’s impact based on careful measurement and analysis.

In fact, that’s the basic outline of the book—we’ll cover each of these topics in detail, along with additional information and techniques that will help you along the way.

The “Design” Part of Designing for Behavior Change

Of these four phases, designing the product itself is the sexiest part, so I devote the single largest chunk of the book to that. Our natural inclination is to jump straight to the product and say, “What should the product do to drive behavior change?” But that’s actually not the best place to start. Instead, we’ll start with the action or behavior that we’re trying to change. We’ll ask how we can reimagine the action, based on what we learned in the first two phases, to make it more feasible and more palatable for the user even before we build anything.

From there, we’ll talk about how to construct the decision-making environment—both the product itself and the surrounding context that the person is in—to support action. And, we’ll talk about how to prepare users to take action with the product.

Here’s a quick outline of the design process:

  1. Action. Structure the target action to make it feasible and inviting.

  2. Environment. Construct the decision-making environment to support the target action.

  3. User. Prepare users to take the target action.

We’ll use this three-step design process for both the conceptual design (figuring out what the product should do) and the interface design (figuring out how the product should look).

Designing for Behavior Change in an Agile or Lean World

Designing for behavior change doesn’t require a specific product development methodology—it is intended to layer on top of your existing approach, whether it is agile, lean, Stage-Gate, or anything else. But to make things concrete, Figure 4 shows how the four stages of designing for behavior change can be applied to a simple iterative development process. At HelloWallet, we use a combination of lean and agile methods, and this sample process is based on what we’ve found to work.

Figure 4 shows you the specific outputs that the team will generate within each stage of the process.

The outputs generated by designing for behavior change at each stage of the process, using a simple iterative product development cycle

Figure 4. The outputs generated by designing for behavior change at each stage of the process, using a simple iterative product development cycle

Let’s assume that a company (or NGO, government body, or individual entrepreneur; I use “company” as a convenient shorthand for any individual and organization making behavior change products) is developing a new product. Here is how this sample process works, and the outputs the team will generate at each stage:

  1. Understand. To start things off, the company gains an understanding of how we make decisions and how our cognitive mechanisms can support (or hinder) behavior change. The two main topics to cover are the prerequisites for action, which are summarized in the Create Action Funnel, and the three strategies for behavior change that companies can use.

  2. Discover. With that knowledge in hand, it clarifies what, specifically, the company wants to accomplish with the product, and for whom. Perhaps the company seeks a world full of (newly) healthy people. The company then identifies the particular group it wants to make healthier (let’s say it’s office workers), and the action it wants to encourage (let’s say it’s walking more); that’s the actor and action.

  3. Design. It’s convenient to think of the design stage in terms of two subtasks—designing the overall concept for the product, and then designing the specific user interface and actually building the product.

    1. Conceptual design. The company develops a behavioral plan, a story about how the user will interact with the product. That’s the high-level conceptual design of the product. The behavioral plan is incrementally built up by examining the action itself, the environment, and the user’s preparation to act. Then, the company extracts user stories: short statements that capture the spirit of each piece of the behavioral plan. The product team will flesh out the user stories in greater detail.

    2. Interface design. The team then develops interface designs, which are reviewed and revised for their behavioral content (action, environment, and user preparation). Next, it’s time to actually build the product. Some engineering compromises and trade-offs naturally occur, and the team reviews them as well for their behavioral impact.

  4. Refine. Once a version of the product is ready for field testing, the team starts to gather quantitative and qualitative data about user behavior to form an initial impact assessment of how the product is doing. A careful, structured analysis of that data leads to insight and ideas for improving the product. That could lead the team members to revise their underlying conception of whom they are helping and how, and generate a new behavioral plan and new user stories accordingly. The new user stories turn into designs, the designs into product revisions, and so on. The spiral continues inward until the desired level of impact is achieved. With each revision, the team makes changes and measurements of how those changes impacted user behavior.

If the company already has an existing product and wants to refine it, the process is similar but starts at a different place. After establishing the desired outcome, actor, and action, the company jumps directly to refinement: measuring user behavior and the product’s current impact, and comparing it against the company’s behavioral goals for the product. Then the team uses that information to drive insights that inform the product’s target actor and actions, behavioral plan, and user stories.

As I mentioned, this particular process follows a simple iterative approach. Of course, you’re not required to follow it (well, you might hurt my feelings). In this book, I also discuss how to employ these methods using a sequential development (aka “waterfall”) process. The key is that you can slot in the tools of designing for behavior change where you need them.

Who This Book Is For

As you can probably tell by now, this book is aimed at practitioners—the people who design and build products with specific behavioral goals. Teams that design for behavior change should generally include the following roles, and individuals in each of these roles will find practical, how-to instructions in this book:

  • Interaction designers, information architects, user researchers, human factors experts, human-computer interaction (HCI) practitioners, and other user experience (UX) folks

  • Product managers, product owners, and project managers

  • Behavioral social scientists (behavioral economists, psychologists, judgment and decision-making experts) interested in products that apply the research literature

The person doing the work of designing for behavior change could be any one of these people. At HelloWallet, we have a dedicated person with a social science background on the product team (that’s me). But this work can be, and often is, done wonderfully by UX folks. They are closest to the look and feel of the product, and have its success directly in their hands. Product owners and managers are also well positioned to seamlessly integrate the skills of designing for behavior change to make their products effective. Finally, there’s a new movement of behavioral social scientists into applied product development and consulting at organizations like ideas42 and IrrationalLabs. So, the people designing for behavior change probably wear other hats as well.

In addition, this book is for entrepreneurs and managers. If you’ve ever read Nudge, Blink, or Predictably Irrational,[2] and wondered how you could apply them to your own product and users, read on. While the book is about helping users take action in their lives, that doesn’t mean that designing for behavior change is incompatible with a for-profit business model. Businesses make a profit; that’s how they exist. So you’ll find suggestions in Chapter 15 for building a successful business model on voluntary behavior change. If in addition to making a profit, you are helping your users take action and change their behavior, this book can help you do it.

Nonprofit entities and some government agencies often explicitly focus on helping users change their behavior; Designing for Behavior Change can help. For example, the United Kingdom government’s Behavioural Insights Team is widely applying behavioral research to UK public policy and the provision of services.[3] Where relevant, I’ll note parts that are particularly important for nongovernmental organizations (NGOs) and government agencies. Because it’s more compact to write, I’ll refer primarily to “companies” here. In almost all cases, I really mean companies, organizations, and relevant government agencies.

Finally, my expertise is software development, so I’ll use the terminology that I use in my day-to-day life—applications, software, and programs. You don’t need to be in software development to find this relevant to you. In fact, some of the most innovative work in persuasive design, one of the fields that this book draws inspiration from, is in the design of everyday objects.[4] As you apply Designing for Behavior Change to your work, whether in software or beyond, I’d love to talk with you and share notes!

Combining Research, Data, and Product Expertise

One of the book’s recurring themes is that understanding how the mind works is not enough to build behaviorally effective products.

In addition to behavioral science research, we need two sets of skills to support the process. First, we need to plan for data analysis (both qualitative and quantitative) and for refinement and iteration based on that data. That means adding metrics to the application and conducting user research to understand individual behavior, analyzing the data, and making improvements over time based on it. Why do we need to plan for iteration? The research literature is invaluable, but we’re just starting to understand how to best apply it to practical product development. There are no magic formulas for behavior change: we’re all unique people, with different histories and personalities. This book will help you take your first, best shot, then fine-tune your product based on what the data tells you about your real-life users and their behavior.

Second, we need to build products that people actually enjoy using. I know it sounds obvious, but it’s something that’s often forgotten as we build products designed to educate, motivate, or otherwise help our users. We tend to focus on the behavior change (and how important it is, etc.), and forget the fact that people still have to choose to use our products. Users avoid boring, frustrating, ugly applications, so we should remember the lessons of good product design: from identifying user needs and frustrations to designing an intuitive, beautiful user interface.

When you bring these raw ingredients together—behavioral research, product design expertise, and data analysis—you have what’s needed to design for behavior change (Figure 5).

Designing for behavior change integrates behavioral research, pragmatic product development, and rigorous data analysis

Figure 5. Designing for behavior change integrates behavioral research, pragmatic product development, and rigorous data analysis

What Do You Need to Know to Benefit from This Book?

This book gives you enough knowledge in each of these three areas to get oriented and to start working on concrete products. It covers most of the behavioral research you’ll need to finish the products as well, but at some point along the way, you’ll need people who are experts in qualitative or quantitative data and in product design.

If you are an expert in one of these areas, all the better. The book will show you how designing for behavior change builds upon and complements your existing expertise. You’ll find out how to leverage your existing skills to play a leading role in the development of behaviorally effective products within your organization.

What Types of Behaviors Can This Help With?

The techniques I’ll talk about here assume that the product will support an action that people aspire to but have had difficulty taking. Learning a language. Sticking to a diet. Meeting new people. This may seem like it applies only to a narrow set of products, but I’ve found that there are two big groups of behaviors that fit this criteria. Both groups of behaviors (and products that work with them) can use this method:

  • Behaviors that users want to change within their daily lives

  • Behaviors within the product itself that are part of using the product

The first group, behavior change within people’s daily lives, includes:

  • Controlling diabetes

  • Paying off credit card debts

  • Getting back in shape

  • Getting involved in their communities

Often these behaviors relate to big-picture social issues, like health and wellness. When we design products that support these behaviors, we help the individual and impact our society at the same time. Opower and Nest, for example, are companies that help individuals decrease individual energy usage: saving people money and helping the environment at the same time. Other products that change behavior in this way are Fitbit (exercise) and Weight Watchers (diet).

In the second group, individuals often seek to change behavior for more mundane purposes. Let’s say a user wants to learn a new language, and gets a software package to help do it. Simply learning how to effectively use the software can take some substantial changes in behavior within the product—building new habits to log in daily and practice the language, overcoming fears about looking foolish while doing it, and so on. The user wants to take an action (learning the language) but struggles. A well-designed product can help the user make those personal adjustments.

This second type of behavior change, and the products that require it, is much broader than the first type. It covers the sweep of voluntary changes in behavior that people might make to benefit from products they’ve already chosen to use. It touches upon a huge swath of the consumer product space, from Yelp to Square to Rosetta Stone. Here are some examples of behaviors that occur within software products that one might try to improve:

  • Organizing email contacts

  • Drawing decent flowcharts

  • Formatting documents

These two types of behavior change also differ from the perspective of the company making the product. Companies can think of these two categories like this:

  • Behavior change is the core value of the product for users; or

  • Behavior change is required for users to extract the value of the product.

In the first case, users have some behavioral problem in their daily lives and buy the product to help them with it. In the second case, users have some other need that the product solves, but they must adapt and change their behavior in order for the product to deliver on its promise.

In both cases, the goal of designing for behavior change is to develop products that help users take action, and to deliver the value that the company offers. This voluntary, transparent support for behavior change helps companies be successful as well.

What it’s not designed for is persuasion, trickery, or coercion (for both practical and ethical reasons).

What This Book Is Not About

If you’re looking for a book on how to make people do something you want them to do (even if they don’t want to do it), you’re in the wrong place. I’m not necessarily judging your motives or aims; I just can’t help you much. Here is what this book won’t cover, and why:

Persuading people

Designing for behavior change doesn’t seek to persuade people to take action, for two reasons. First, it relies on the fact that people already want to act. Second, it’s fundamentally about action and not about beliefs or intentions; the goal is to help people do something physical in the real world. It’s in the real world of action where good intentions often fail.


This involves tricking people into doing something they don’t want to do. In many cases, taking a “hard” action takes numerous small steps. Putting aside the morality of manipulating people, it’s simply impractical in this scenario—people wise up somewhere along the process of small steps. It’s hard to build a sequence of actions around trickery.

Coercing people

Few products can force people to do something. And, to be frank, the techniques in this book are largely ineffective when the person is being coerced. Thankfully, people find creative ways to resist coercion.

For different reasons, there are a couple of other things that I don’t focus on here:

Clicking a button on a single page

We’ll certainly talk about how to support that action, because that’s a basic building block of online applications, including those that change behavior. But if that’s all you’re trying to do, get a book on testing web designs, run dozens of experiments, and then go with the best one. This book focuses on more complex and challenging behaviors.


Many of the habits that people want to stop are tied to a chemical addiction (i.e., drugs or alcohol) or an underlying disorder. The neurobiology of addiction and of psychological disorders that cause deeply ingrained and undesirable habits are beyond the scope of this book. I do provide a section on how to avoid triggering existing habits and how to build new habits that seek to displace existing ones, but those sections are geared for less intractable behaviors.

Because we’re not focusing on stopping addiction, and because most of the ways to stop a (less pernicious) habit involve overcoming the habit with a different action, I’ll often refer to “behavior change” and “taking action” interchangeably here. That makes writing and reading this a bit more interesting, too.

Behavior Change and the Dark Arts

While the goal here isn’t persuasion or coercion, there’s no escaping it—this book builds upon research into what I half-jokingly call “the Dark Arts”: using products to change people’s behavior when they aren’t aware of what you’re doing, or when it’s explicitly against their will. Many of the cognitive mechanisms that I reference in this book have been studied in the fields of consumer behavior, marketing, and sales for decades. Some of the research in these fields has been laudable, and used to better understand what people really want. But much of it has been used to push products that people don’t want, don’t need, and can’t afford. In 1957, Vance Packard’s book The Hidden Persuaders (Pocket Books) decried the tricks that advertisers used at the time; the techniques have only gotten more advanced since then.

The Dark Arts are Similar…

To drive sales, companies have invested heavily over the last few decades in understanding how the mind works. Books such as Paco Underhill’s Why We Buy (Simon & Schuster, 2000) and Martin Lindstrom’s Buyology (Crown Business, 2010) detail how companies have used everything from randomized control trials about product placement to fMRI brain scans of brand exposure to understand how we, as consumers, tick.[5] Behavioral economics and the psychology of judgment and decision making, both of which I rely heavily upon here, study many of the same cognitive mechanisms but in different contexts. The brain is the brain, whether it’s telling the body to buy soap or to exercise more.

What’s been lacking, I believe, in the study of “stuff that’s good for you” (exercise, good diet, financial control, etc.) has been an honest assessment that we’re actually doing some similar things as companies selling products—we just aren’t doing it as well. Realistically, most diet programs, personal finance tools, political advocacy campaigns, and Bible study groups have always been about changing people’s behavior. Marketers already know this, and some of them apply their craft to pursue explicit social goals (aka “social marketing”).[6] But the rest of us have just tried to hide from that fact, and so we’ve been ineffective.

I figure that if you say that you want to build a product that’s designed to help someone, don’t dance around the issue: get off your butt and actually do it. There’s just no point to designing these products if they are ineffective. That’s not to say that we should start moral crusades in the name of helping people whether they like it or not. We need to be cautious and humble, check our assumptions about our products, and verify that our products are voluntary, transparent, and beneficial. If they are, excellent. Use human psychology to help people take control of their own lives.

…But Not Identical

On the other hand, if we can learn so much from the manipulative side of sales and consumer research, why do we need something new? Why not just provide a list of books on effective sales techniques and call it a day? There are some key differences between designing products for behavior change and marketing/sales. Products that engender different types of behavior look and act differently. We’ll build upon their research, but apply it in a very different context.[7]

Focusing on voluntary change helps one scale back the unmanageable topic of behavior change into something more digestible and practical. For example, pushing someone to buy a product that he wouldn’t otherwise buy is a very different task than helping a recovering alcoholic avoid cues in the environment to drink. Also, if you assume people want to take a particular action (but haven’t been able to), you can focus on the relevant research and dispense with discussions of preference generation, dissonance, manipulation, and so on. Similarly, focusing on software applications and digital-physical tools like the Nike+ FuelBand allows us to avoid tangents about person-to-person coaching, therapy, and the like. It usefully narrows the range of possible psychological mechanisms and approaches to a reasonable set that one can work with.

And Hopefully, This is More Sustainable

I also firmly believe that designing for voluntary and transparent behavior change is also the most sustainable path, from a product development perspective. This isn’t the first time that behaviorism has taken hold of the social sciences and of businesses practices—it flowered in the early to mid-1900s under researchers such as John Watson and B.F. Skinner. Behaviorism eschewed internal mental states as primary causes of behavior, and looked to environmental factors to explain and ultimately change behavior. This approach dominated psychology and strongly influenced behavioral research in other social sciences, but a backlash against the external, mechanistic view of behavior finally overcame behaviorism. Behaviorism’s fall had many causes, but one enduring critique is that viewing people as mechanical devices led to an atheoretical, soulless view of humanity, and one in which researchers sought to control or manipulate us.

When I see books about “how you can get people to do anything,” first I laugh—since most of those books tremendously exaggerate the real research that’s out there. Their authors are deceiving themselves, their readers, or both. But I also cringe—because I know that that manipulative approach invites a backlash.

So this book takes a middle path—using the tools of behaviorism, along with other traditions within psychology and economics, to be effective at changing behavior, but being transparent about it and focusing on voluntary action, to avoid that backlash. I think we can do something new and different with the research. We’ll see how it goes.

How This Book Came About

I’m the head research guy at HelloWallet, and the idea for this book started with my own experience, and the experiences of all of us at HelloWallet. For many years now, we’ve sought to help our users take control of their finances and make the best use of their employee benefits. For some people, that means saving up money for emergencies, so they don’t fall deep into credit card debt when someone gets sick or the car breaks down. For others, that means getting free of debt. And, for some, it means saving money for retirement, their kids’ education, or a really cool vacation they’ve always wanted to take.

The basics are simple—we provide online and mobile applications to help people understand their current financial situation and then help them take action. Our members are primarily the employees of large companies who buy our software to help their workers get ahead financially. We’re currently serving the employees of some of the best-known companies in the country—from retail workers at your local outlet mall to the investment bankers handling your 401(k) at T. Rowe Price, and from the people that put ketchup into Heinz bottles to the ones who designed the Black Hawk Helicopter at Sikorsky. At these companies and others, we’re helping their employees take control of their finances.

The details are much more complex. We started out building software that told people what do to. We looked up the relevant mathematical models for optimal financial behavior and piped them into the application as marching orders for our users. We quickly found out that no one listened. They didn’t want to be yelled at.

So we started looking for models that worked. Around that time, Richard Thaler and Cass Sunstein’s book Nudge came out, showing how behavioral economics was being applied to nudge people into better behavior. We dug into the literature in behavioral economics and related fields, and assembled an academic advisory board of great researchers from across the country. They helped us parse the academic literature, and put it into practice in our applications.

We found that the translation process—from academic research into real products—was far from straightforward and easy. Our first attempts flopped, to put it bluntly. We designed features on the cutting edge of academic knowledge, with all indications that if people used the features, we would transform their lives. Well, we found that people just didn’t use those features. A product that could change behavior is useless if no one wants to use it. So, we hired good people with real expertise building consumer-facing products (something we had lacked, unfortunately). We tested the heck out of our app. We fixed the parts that were broken, and developed a user experience that people enjoyed using.

After all of this, we’ve finally crossed the threshold. We’re helping our users take control of their finances. For example, we ran an experimental study with a set of independent researchers, and found that one feature (the “Guided Approach”) caused our users to put aside $100–$200 more in a month than they otherwise would have. To put that in context, for the median US family earning about $50,000 a year, that represents an additional 5% of their salaries saved for the future. That means more than doubling the US savings rate (about 4%, on average).

Along the way, we learned that in order to make behaviorally effective products, you need three things:

  1. The product and design expertise to build something that people will actually like

  2. A clear understanding of user behavior and how to influence it

  3. A commitment to testing the heck out of your product and listening to what the data tells you

My personal story has been intertwined with that of HelloWallet for the last four years. I’m a political scientist by training, and my research focused on how people change their political behavior by interacting with their local environment over time. In 2007, I cofounded a micro-targeting company that employed machine learning and simulation modeling to find new volunteers for political advocacy groups—and then (successfully) encouraged them to get involved. The math worked, but the business model didn’t. So, a year later, I started looking around for other options. My cofounder and I happened upon HelloWallet, and were inspired by the promise of democratizing access to financial guidance for everyone. I quickly joined HelloWallet as its first full-time employee.

Initially, I was HelloWallet’s (only) software engineer, designing and developing a highly detailed (and, in hindsight, completely unrealistic) simulation model of financial behavior over an individual’s lifetime. Later on, I ran the engineering team, and then headed up the quantitative analysis of our application. Along the way, I attended BJ Fogg’s Behavior Design Bootcamp, and applied the behavioral economics and psychology literatures to develop new ideas for the product.

I’m currently HelloWallet’s principal scientist, and my job entails digging through the academic literature for product insights, running experiments on how to improve financial behavior, and coordinating our academic advisory board. I’ve also had the fun privilege of organizing Action Design D.C., a Meetup group of behavior change practitioners in Washington, D.C., that focuses on learning from one another’s efforts to support behavior change.[8]

So, when I mentioned the mistakes and lessons that HelloWallet learned—about mathematically correct but behaviorally unrealistic models and academically interesting but unengaging product features—those were, to a large extent, my own mistakes and lessons. At HelloWallet, we’ve run the gauntlet and come out the other side with a product that’s both beautiful and effective. This book comes from our experiences, and from the lessons we’ve learned through Action Design D.C. and conversations with like-minded groups around the country.

It’s my sincere hope and belief that this book can help you skip over some of the mistakes I’ve made along the way, and jump straight to the fun part—learning how to best help your users take action.

The Chapters Ahead

In the following pages, I walk you through each of the skills you need to design for behavior change, starting with a firm foundation in how the mind makes decisions. Then, I show each step that’s required to develop a new product, using the simple iterative product development process shown previously in Figure 4: moving from discovery to design to implementation to refinement. I introduce each concept where it is first needed. In the concluding chapters, I step back and give some additional tips on how to use these skills in practice, how to apply these techniques to refine existing products, and likely problems you’ll face along the way. That’s it.

However, if you’re looking for a more formal chapter outline, here you go:

Part I

Chapter 1 arms you with your first skill: an understanding of how the mind makes decisions. You’ll get an overview of the current literature on decision making, as well as a dozen key lessons and their implications for the design process.

Chapter 2 describes the five high-level factors that must come together at the same time for a person to take action. They form the Create Action Funnel, which shows you what needs to be addressed in your app and where users usually drop off. The funnel will help you diagnose and fix problems in your products.

Chapter 3 develops three specific strategies for changing behavior. In short, you can focus on our conscious mode of thinking or on our habits, or you can shift the burden of work from the user to the product (what I call “cheating”). You’ll reuse these three strategies throughout the product development process.

Part II

Chapter 4 starts charting your course by discovering the overall outcomes you hope the product will deliver and who it seeks to help. From there, it demonstrates how to brainstorm potential ideas for behavior change—how, specifically, your users will get fit or take control of their finances, for example.

Chapter 5 gathers knowledge about your users, and then evaluates the various behaviors they could change in light of their needs, interests, and prior experience. It shows how to analyze the (behavioral) cost-effectiveness of various actions, and how they affect the bottom line of a company. It also demonstrates how to make a decision and select the specific behavior that the product will support.

Part III

Chapter 6 introduces you to the meat of the process: designing the product itself. You start by structuring the action so people will actually take it! This task includes breaking the problem down into component steps, tailoring it based on your user research, and making it understandable and feasible. To make the discussion concrete, this section also starts the idea of a conceptual design or behavioral plan: a narrative of how the product team envisions user interaction with the product and how users will change their behavior.

Chapter 7 covers the second part of the design: how to construct the environment—especially the product itself—so that the user is encouraged to take the action. Naturally, this involves motivation, but I discuss how that is often not the core issue with behavior change products. You can encourage action with an immediate cue to act, a feedback loop, removing distractions, and avoiding user-specific obstacles.

Chapter 8 completes the design process with a discussion of how a product can prepare users for action ahead of time. I talk about how to help users rewrite their personal narrative to weave in action, how to build a behavioral bridge between the new action and other things they are familiar with, and how to provide users with information and education, especially about the task ahead.

Part IV

Chapter 9 moves from the behavioral plan, or conceptual design, to the interface design. I discuss how to convert the behavioral plan into user stories or written specs, and then into wireframes and graphic designs.

Chapter 10 delves into how to review a set of interface designs for their behavioral impact. I show you how to reapply the core design process (gather knowledge, structure the action, construct the environment, and prepare the user) at a more detailed, tactical level.

Chapter 11 is about implementation: how to build the product from the designs. I talk about the collaboration between the product team and the engineering team, and how to evaluate the behavioral impact of design revisions. Early user feedback on the product (hopefully in a prototype phase) can help immensely.

Part V

Chapter 12 focuses on assessing the product’s impact: its success or failure. I cover how to instrument the application to track essential data, and how to use experimental methods and statistical models to gain insight. I talk about the challenges of gauging the causal impact of software on real-world behavior, and how to overcome them.

Chapter 13 delves into another aspect of data gathering and analysis: finding the problems that limit impact. I also discuss how proper instrumentation can identify bottlenecks in the application that are limiting impact. This chapter also discusses how qualitative and quantitative analyses are both needed, and work hand in hand.

In Chapter 14, I talk about how the lessons from the measurement process can be reapplied in later versions of the application. I also discuss how designing for behavior change fits into the product development processes, and how it can be applied to retrofit existing products.

Part VI

Chapter 15 covers some of the questions that can arise when putting these lessons into practice, such as how to build a sustainable business around behavior change, and how to sustain engagement with your product.

Finally, Chapter 16 wraps things up with a quick review of the designing for behavior change process and key takeaways on how to make it happen in your organization.

In the appendixes, there’s information for those who are looking to dive even deeper into these topics:

  • A glossary of key terms, like “behavioral plan” and “data bridge”

  • An annotated list of resources for learning more about psychology and product design

  • The book’s bibliography

Each of the core chapters ends with a quick summary of the approach, if you only have a few minutes. It’s a useful wrap-up and also gives advice if you’re just looking for an informal process to sketch things out before you jump in head first. In honor of the many people coming up with exciting ideas to start new companies based on a concept sketched on a cocktail napkin, the summary sections of each chapter are titled “On a Napkin.”

Let’s Talk

My hope with this book is to further the conversation about voluntary behavior change and help build up the tools needed to develop behaviorally effective products. However, I have no illusions about the completeness of this work—there’s still a tremendous amount to figure out. We’re all going to learn as we go along.

Personally, I’m always looking to learn, share, and collaborate, so please don’t hesitate to reach out to me if you have a cool story to share, an idea for a research project that would further develop the field, or just an idea for a behavior-changing project that you’d like to bounce off someone. In most places, you can find me under “sawendel” (Twitter, LinkedIn, AngelList); you can also find my up-to-date contact information at

If you think there’s something that can be improved in this book or something that is inaccurate, please reach out to me and tell me about it. One of the many benefits of working with O’Reilly Media as a publisher is that a lot of you will be reading this book in an electronic format and can quickly get an updated version of the book if corrections need to be made. For those who are reading this in paper form, I’ll keep a list of corrections, additions, and other updates online at my blog,


I am pleasantly indebted to dozens of people who have encouraged my writing this book, given feedback and comments, or sparked new ideas during one of the many workshops and talks I’ve held with unsuspecting audiences to iron out these concepts. At HelloWallet, where I work, I’m particularly thankful for the support, encouragement, and feedback of Paul Ballas, Aaron Benway, Jaime Dalbke, Matt Fellowes, Matt Garza, Katherine Kendall, Rajesh Nerlikar, Rob Pinkerton, Evan Samek, and, especially, Michael Yoch. Also, a number of the graphics in this book come from the expert hands of Heyjin Kang, Alisa March, and Katie Palermo.

Beyond HelloWallet, the list is long and diverse (with my apologies to those I’ve missed): Dave Aidekman, Denis Baranov, John Beshears, Danny Boice, Cameron Breslin, Julia Brown, Jim Burke, Anna Cash, Chris Daggett, Nir Eyal, BJ Fogg, Spencer Gerrol, Zach Goodwin, Peter Jackson, Erik Johnson, Warren Jokinen, Panayiotis “Dr. Voodoo” Karabetis, Keri Kettle, Shreya Kothaneth, Maxim Leyzerovich, Ronnie Lipton, Neale Martin, Katy Milkman, Michael Mentzel, Enio Ohmaye, Anastasiya Pocheptsova, Brendan Robinson, Justin Thorp, Remi Trudel, Anna Tulchinskaya, Katya Vasilaky, Marko Vasiljevic, Jonathan Zinman. My editor, Mary Treseler at O’Reilly, has been a pleasure to work with, and I appreciate the help and thoughtfulness of my technical reviewers: Tom Boates, Sebastian Deterding, Randy Farmer, Karl Fast, and Samantha Starmer. And, most of all, I’d like to thank Alexia Muchisu, for putting up with me while I was writing and for taking care of our entertaining and surprisingly energetic son.

Research and Inspiration

There’s a great excitement and flurry of activity around beneficial behavior change, and throughout this work, I cite researchers with studies that are particularly relevant or that I’m directly building upon. But I should thank five people for their inspiration above and beyond their printed words and research studies:

  • Joe Oppenheimer—theorist, experimentalist, chair of my dissertation committee, coauthor, friend, and sourdough baker

  • Jon Zinman—behavioral economist, advisory board member, and unofficial, unpaid mentor in all things behavioral economics

  • John Beshears—behavioral economist, advisory board member, discussion partner, and sounding board

  • Nir Eyal—entrepreneur, thinker, master storyteller, and co-traveler trying to level the playing field for beneficial behavior change

  • BJ Fogg—social psychologist, innovator, behavior change leader, and teacher of the Persuasion Bootcamp, which spurred my journey into product-mediated behavior change

Like many researchers, I believe that there are no truly new ideas—only new ways to present and organize old ideas. If you see a compelling idea in this book, without a specific citation next to it, the odds are good that one of these five people originally inspired it. I am deeply grateful for their leading the way.

[4] Dan Lockton has a set of working papers (and published papers) that provide an extensive review of the various domains in which intentional behavior change has been applied. See

[5] The Dark Arts have also been applied specifically to software user interfaces. [ref140] and [ref25] have a book and website, respectively, devoted to documenting intentionally deceptive user interface practices.

[6] Social marketing entails using the techniques of marketing for beneficial behavior change and explicit social good. For example, [ref135] talks about a social marketing campaign by the organization Men Can Stop Rape that features members of the D.C. United Soccer team stating, “My Strength is Not for Hurting,” with the explicit behavioral goal of delegitimizing rape. See [ref170] for a recent review of the field and its effectiveness, and [ref85] for public health applications of social marketing.

[7] In addition, some of the lessons about behavior and behavior change reviewed in this book haven’t been applied in fields such as sales and marketing (for either positive or negative applications). Neale Martin’s book Habit (FT Press, 2008) describes how habits are often ignored in marketing efforts, even though they drive most of our purchasing behavior.

[8] If you’re in the D.C. area, even if you’re just visiting, come check us out—information about the group can be found at We also have an online forum ( for sharing product ideas, research summaries, and more.

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