Beyond Usability: Designing Web Sites for Persuasion, Emotion, and Trust

By Eric Schaffer

Published: January 26, 2009

“The next wave in Web site design is persuasive design, designing for persuasion, emotion, and trust. While usability is still a fundamental requirement for effective Web site design, it is no longer enough.”

The next wave in Web site design is persuasive design, designing for persuasion, emotion, and trust. While usability is still a fundamental requirement for effective Web site design, it is no longer enough to design sites that are simply easy to navigate and understand so users can complete transactions. As business mandates for Web site design have grown more strategic, complex, and demanding of accountability, good usability has become the price of competitive entry. So, while usability is important, it is no longer the key differentiator it once was.

The future of great Web design is about creating customer engagement and commitment in a way that clearly impacts business results and measurable goals. Whether a Web site is e-commerce, informational, or transactional, it must motivate people to make decisions online that lead to conversion of one sort or another.

The interactive online environment offers far more opportunities to influence customers’ decision-making than traditional advertising or marketing channels do. By leveraging the science of persuasion in new and insightful ways and designing specifically to optimize the elements of persuasion, emotion, and trust, we can systematically influence customers’ online behavior.

Our approach to persuasive design at HFI—called PET design™, which stands for Persuasion, Emotion and Trust—has its basis in a deep understanding of customers’ subtle emotional triggers and employs a rigorous set of new, research-based methods and techniques. This article presents a strategic overview of HFI’s take on persuasive design, or PET design.

Persuasive Design

“User engagement rather than classic usability is what sets effective Web design apart today.”

To be clear, persuasive design is not entirely new. It builds on the work of many researchers and innovators over many years. Systematic and scientific methods of persuasion have been in use since 1920, when Dr. John Watson applied conditioning methods to sales of Pond’s Cold Cream and other products. Continuing that innovative tradition, HFI’s approach, methodology, and insights are advancing the dialogue about and practice of persuasive design and demonstrating that online persuasion’s time has come.

User engagement rather than classic usability is what sets effective Web design apart today. While great usability is a baseline requirement, there is far more involved in engaging customers on a Web site than simply making sure they can find specific content and perform particular transactions. Today’s mandate is to move beyond traditional usability. Instead of designing only for what visitors can do on a site, superior Web design is now responsible for determining what customers will do—whether it’s to

  • buy a product or service
  • ask their doctor about a new drug
  • decide to vote for an issue or a candidate
  • donate to a particular cause or philanthropy

With its foundation in usability best practices and psychology, PET design is the result of HFI’s extensive research, pilot programs, and client engagements with Fortune 500 companies. It is based on a new model that employs a holistic view of user experience design in which persuasion objectives lead to business success.

The Critical Persuasion Objective

“Once a customer has entered a Web site, we must create a sense of trust, or there will be no transaction.”

Most e-commerce sites used to be the equivalent of bricks-and-mortar stores with barbed wire fences. Customers could barely find their way in, no less find what they were looking for or complete a transaction and check out with ease. Now that usability practices have become widely adopted and the barbed wire is gone, it’s necessary to go beyond just providing an open door. We need to create an online shopping experience that is persuasive.

The online shopping experience must be motivational for customers, not just easy and satisfying. A rating of high satisfaction does not ensure a conversion. We need to create an experience that motivates action.

Once a customer has entered a Web site, we must create a sense of trust, or there will be no transaction. Users assess a site’s credibility in a moment, then also make a longer-term evaluation of its trustworthiness. Two different sets of markers in a site’s design provide the basis for these two evaluations:

  • Superficial markers like layout and graphics provide the basis for fast, thin-slicing evaluations.
  • The quality of information, credentials, and references are the focus of more involved evaluations.

Only once we’ve established trust can we apply specific research-based methods of persuasion to drive a customer to make a transaction, or convert—that is, to achieve the persuasion objective that is the focus of PET design. For example, a usability engineer can make it easy to purchase insurance online. But ease of use is not the main driver of why people buy a policy—rather they buy a policy because a site has persuaded them to buy it. This could be accomplished by appealing to someone’s sense of security, safety, and responsibility. What might happen to their family if they don’t buy insurance? Through persuasion methods, we might make a policy seem inexpensive or make someone feel obligated to buy a policy.

Persuasive Design and Research

“Persuasive design is fundamentally more qualitative, deep, and subtle than usability.”

For companies and designers, persuasive design changes virtually everything about planning a Web site. Standard usability research and testing are often no longer adequate. Persuasive design is fundamentally more qualitative, deep, and subtle than usability.

Consider this scenario: Meet Sam, who’s a usability test participant for a site that sells spa products. Even though Sam is not a target user, researchers could still evaluate whether Sam can find particular spa products on the site and purchase them easily.

However, persuasive design also requires examining how participants feel about buying a product, whether they would buy, and whether a site motivates them to buy. So Sam—a 50-something-year-old male with two 20-year-old sons, no daughters, and no interest in spa products whatsoever—is just about useless for a PET design evaluation of a spa Web site.

Who the test participants are, what questions the test facilitator asks them, and how she frames the questions—all matter a great deal more in a PET design evaluation. The research and testing are more exacting, because we’re looking at human preference and decision-making. So we need to go further in our research. We probe the depths of customers’ drives, uncover their deep beliefs and feelings, and understand the blocks and fears that keep them from taking particular actions.

Emotion, Decision-making, and Optimizing Engagement

“The thinking processes that guide our commercial choices are complex and emotional, not logical and linear.”

The thinking processes that guide our commercial choices are complex and emotional, not logical and linear. Malcolm Gladwell’s book, Blink: The Power of Thinking Without Thinking, deals with the primary role that snap judgments play in consumer decisions. Gladwell cautioned marketers to be careful about using what people say while sitting around a table responding to what-if scenarios.

While Gladwell’s point is a good one, at HFI we’ve shown it is possible to design for persuasion by modeling what the deep parts of the human brain are doing—going further than simple what-if scenarios. We’ve also found it’s possible to do so in a methodical and scientific manner that is informed by research and validation rather than guesswork. Understanding this framework is one of the keys to persuading someone to make a decision. We must model the implications of a user’s old brain—the amygdale, hippocampus, and basil ganglia. Charting a user’s completely unconscious cognitive processing can be as critical as looking at beliefs and feelings. This is how PET design results in desired actions and, therefore, meets business objectives.

Case Study: State Lottery Web Site Redesign and Results

Let’s look at an example. HFI was recently engaged to redesign the California state lottery Web site. Most people didn’t know the state’s lottery was created to generate extra funds to support public education. While the lottery Web site reminds people to play responsibly, its goal is to encourage them to participate in more games, more often—thereby generating more income for education. The site is also an important means of communicating this meaningful contribution to people—particularly to lottery skeptics.

While the site suffered from usability problems, more importantly, it failed to capitalize on opportunities to engage site visitors and convey the key brand values of optimism, hope, trust, and fun. HFI’s PET design research found that people play lotto because of the anticipation, excitement, and adrenaline rush it creates. Rationally, they don’t expect to hit the jackpot. People admitted they probably had better odds of being struck by lightning. But they’re still happy to buy a $1 ticket for the chance to dream about what they’d do if they won—it’s an emotional adventure.

Yet the Web site did little—from an emotional design standpoint—to leverage those feelings and create a stronger connection and engagement with lottery games. It was fundamentally an information site that made playing the lottery less fun. For instance, it simply reported winning numbers instead of replicating the emotional experience of watching the announcement of winning numbers on television.

So, HFI applied a host of classical usability techniques, plus our new PET design methodology. Once we’d discovered and defined the key user motivations, drivers, blocks, and barriers, we created innovative design elements to fulfill the aspirations of site visitors, including

  • dynamic winning number results that simulate the TV experience
  • winners near you
  • lucky store locations
  • lucky number generator games
  • maps showing where the education money goes
  • surveys that ask What would you do if you won?

These new elements engage visitors in ways that remove barriers and blocks and encourage deeper interaction. During the redesign, HFI’s experts were careful to ensure users could complete key tasks that are critical to the lottery’s business goals, while still making them more fun and enjoyable. Through the PET design process, HFI developed a new site prototype that

  • nearly doubled task completion rates—from 47% to 93%
  • 91% of users preferred to the old visual design
  • generated a more positive response to all nine of the brand attributes we tested—such as reliable, friendly, and trustworthy
  • reinforced the lottery’s mission of supporting education, which is important in allaying people’s doubts about where their money goes when they play

When Usability Conflicts with Persuasion

“Persuasive design pushes designers to clearly define a Web site’s purpose—and its persuasion objectives.”

Once usability studies helped us understand how people actually use Web sites, marketers and designers started learning to think differently—and more clearly—about how they wanted people to use Web sites.

Persuasive design pushes designers to clearly define a Web site’s purpose—and its persuasion objectives. For e-commerce sites, the objectives are to inspire their customers’ trust, engage them, and persuade them to buy their products or services. For government sites, the persuasion objectives would likely be to convince citizens that the government is responsible, effective, and investing their money wisely. For non-profit organizations, the objectives would be to engage customers and get them to support their causes with donations and through word-of-mouth and political support. Only after identifying such persuasion objectives and articulating them precisely can we choose the appropriate techniques from our toolkit of persuasion technologies. For example, with PET design, HFI applies very specific techniques that are based on the principles of social pressure, scarcity, or contrast.

In some ways, persuasive design can actually be easier to implement than classic usability. Persuasion-oriented goals and design elements are often minimal in scope when compared to classic usability goals like making every error message on an enterprise site intelligible. Yet the strategies behind persuasive design are not trivial. The design methodologies are also different from those of usability—in fact, they sometimes conflict with each other.

Let’s look at an example. Making people feel engaged and committed is intrinsic to persuasive design. To achieve this, it may be important to make them feel effective when using a user interface. Though the cardinal rule of usability is to make it simple, it’s possible to make a design too simple, thereby causing users to lose the feeling of effectiveness and engagement that stems from a more involved, complex interaction. So, if you want users to experience a sense of discovery or achievement, consider intentionally building in some interesting sources of challenge for them to overcome along the path.

There is another important concept working against strict simplicity in design:
e-tailers want customers to encounter as many products as possible, just as retailers would in a bricks-and-mortar space. Yet their objective to cross-sell and up-sell can conflict with usability best practices.

Think of a shopping mall. If you’ve come to the mall to buy a widget, you’ll invariably find the widget store is on the farthest end of the mall from where you started, forcing you to pass many other stores along the way. If the store that carries your widget is a large one, the pattern repeats anew—you pass through perfume, ties, jewelry, and watches before you finally reach the widget department. Was getting from your car to the item you came to buy an efficient process? From a strict usability perspective, no. You may even have gotten lost along the way. But is it poorly designed? Quite the contrary. While making your way through the mall, you probably discovered many things you didn’t think you wanted, but may end up purchasing.

So, retail spaces are designed not to optimize efficiency, but to optimize persuasion opportunities. The same principle applies in the online environment. While preserving usability, so users don’t feel frustration or other negative emotions, it’s still possible to create a more interesting and entertaining user experience that maximizes persuasion opportunities.

The Science of Trust

“An organization must systematically foster user trust.”

Another critical component of persuasive design is establishing trust between the customer and the e-tailer from the start. Only on a platform of trust can we persuade customers to take the actions we intend on a site. But it’s not enough to simply want to be trusted. An organization must systematically foster user trust. HFI has deeply researched how to establish trust in the online environment and determined what variables are most significant in doing so. Because we’ve gained a systematic understanding of how to establish trust rather than leaving the result to chance, we’ve been able to develop a range of very specific trust-building techniques.

One example is the seemingly prosaic FAQ. A considerable body of research supports the idea that FAQs are very effective in establishing trust. A FAQ on a Web site indicates the organization behind the site is not a fly-by-night operation, but a solid enterprise that is diligent enough to care about documenting such things.

Another trust technique is matching existing knowledge—that is, presenting a piece of information users know is true to strengthen the credibility of your subsequent claims. We know from research that people feel more trust in Web sites that provide information they already know to be true—for example, a recommendation on a Web site focusing on health to take aspirin for heart longevity. It might seem odd to include content that covers what users already know, but seeing the known content makes users more confident in new information on the same site.

Another method of establishing trust is arguing against self-interest. HFI consults with one of the world’s largest computer manufacturers. On their Web site, they frequently recommend options, which can be helpful, but we became concerned when we discovered that all of the recommendations were for the most expensive options. To engender trust, it would be better to sometimes recommend the cheapest option. Once customers experience a company’s telling them You don’t really need to buy that from us, their trust rockets, likely resulting in many more sales.

PET Design Versus Traditional Marketing

“Though persuasive design is based on the user-centric perspectives usability experts already have, the scientific methods for achieving persuasive design are new.”

HFI’s approach to persuasive design—PET design—goes beyond what traditional advertising or marketing agencies do. Persuasion is the name of the game for them, too, but the tried-and-true techniques of priming, framing, and conditioning—which get people to feel that a product is familiar, good, and attractive—are usually applied in older, static media in which messaging flows only one way.

PET design takes root in the dynamic and interactive environment of the Web 2.0 universe. It lets us go far beyond traditional marketing approaches to use persuasion tools and techniques such as influence methods that make a product or service appear particularly appealing. It covers the triggers that can be fired off to make people commit and take action. Ultimately, the goal might even be to create fanatics for your company or brand.

While there will always be a role for classical usability specialists, persuasive design requires the development of a new skill set. Though persuasive design is based on the user-centric perspectives usability experts already have, the scientific methods for achieving persuasive design are new. Usability specialists and designers can add greatly to the value they offer their companies by expanding their toolkits with persuasive design skills. Through this article, I hope I’ve encouraged you to explore the possibilities persuasive design presents.

Additional Resources

  • My new blog, Usability Is No Longer Enough, is dedicated specifically to the topic of persuasive design. I invite you to share your ideas there.
  • For a more detailed explanation of specific PET design techniques, please see HFI’s white paper, “Designing for Conversion,” by Mona Patel.


“Another method of establishing trust is arguing against self-interest.”

I have trust issues with this article. There are some pretty strong claims about “deep research” and “science,” and yet no citations are listed.

This article reads like an HFI advertisement as opposed to a thoughtful discussion or analysis of persuasive design….

Hear, hear to the commenter above.

For example: “A considerable body of research supports the idea that FAQs are very effective in establishing trust.”

My experience with people using FAQs is that Frequently Asked Questions essentially equates to “NMQA” - “Not My Question Answered” Citations please!

Also, where can I learn more about “PET”? Why, that’ll be by signing up for HFI’s multi-day training course costing many hundreds of dollars.

Snake oil!

The retail mall analogy is completely bogus. The reason we’re happy to wander past other stores to reach the one we want is because the alternative is to build a new road to every single store.

Online is not the same as offline. It is a different world with different rules. Because technology allows us to create fast and efficient online journeys, users simply expect this and are turned off by attempts to block their progress. The idea that you should proactively create challenges for users to overcome—except in a gaming environment—is frankly laughable.

Let me take a minute here! Thanks for all these comments, and I’m delighted to see so much interest. I would have responded sooner, but this “marketing ploy” seems to be keeping me pretty busy. :-)

Actually, this persuasion work is very well researched. Probably at least as well as the classic usability work. Take a look at the books by Caldini, by Fogg, and by our own CTS Susan Weinschenk. I also love the work of Dan Airely—see “Predictably Irrational.” Of course, this is all on a foundation of behavioral and social psychology dating back to Dr. John Watson—see the “little Albert” studies—circa 1920. We are pulling this to focus on computer applications. And that is hardly new. I published “Predicators of Successful Arcade Games” in 1981. But this is a moment in the industry when design for emotion and persuasion are the key differentiators.

The FAQ finding surprised me a bit also. But it is a common research finding. (Sillence, E., Briggs, P., Harris, P., & Fishwick, L. (2006). A Framework for Understanding Trust Factors in Web-Based Health Advice. International Journal of Human-Computer Studies, Vol. 64, Issue 8, 697-713.) Maybe think about why this would increase trust. We are not talking about your personal experience with FAQs that are useful or not. We are talking about the presence of a FAQ indicating that someone is listening to questions and cares. I am not saying this is a true perception. But it does generally work. That and a very long list of other things of course. These are the new indicators of trust in commerce. No longer teak wood and snooty sales staff.

Now I almost take offense to the idea that I might be clueless about the difference between online environments and physical stores. After all, I’ve been working in online user experience since 1978. But let’s talk about the idea of building navigation that exposes people to more choices. For example, the structural work we did with AAA doubled the number of services people remembered after using their site and that project broke even after less then a month of increased sales. This is not about forcing people through stuff they don’t want. It is about providing them with a series of things they do want, which we do with a PET Sort. (Yes, you have to pay to learn that one.) But think how you hate getting stuck and can’t find your way out of a store in a mall. It is awful. Unless, of course, you are in the hardware (male) or cosmetics (female) section. Then you are fine. We are talking about creating a positive flow experience by giving people what they are interested in at the moment they would be seducible.

Thanks for quoting your sources. I, too, was a bit skeptical at the outset.

My first reaction was to ask really How is PET any different from the age-old use of guided portals? Usability studies led—erroneously, in my humble opinion—to these models.

The true issue is, of course, just as with usability, that all results are skewed by the subjective / objective dilemma. How can PET be any different? There is an excellent article out there by Robert Hoekman, Jr. at ALP, that reviews an old study on usability. It talks about what I always suspected. You can ask all the right questions and come up with the wrong answers—and all too often, the results are skewed by the users and the observers. Talk about the Hiesenberg Uncertainty Principle in action. :)

So how is it that you defeat this issue? As you can see by the response to the article, the observers all have varying points of view. I personally seek an objective, valid path to guide our users to the destination they need—not necessarily the one we want. (I liked that part of your article. Asking the user to spend less seems counterintuitive to sales, but I have found it to be true. Give them what they want, and they will customize the heck out of it.)

All in all, a thought-provoking read—especially now that there are sources linked, so I have more to study.


I’m not sure how next wave any of this really is. In fact, just the phrase next wave seems to be an outdated concept in itself.

But I would think Persuasion and Emotion—although perhaps not the predominant marketing buzzwords behind Usability with a capital U—are the very cornerstone of any good design work.

Design needs to draw the eye and then drive the viewer-user-participant to certain elements—that’s Persuasion.

And then, hopefully, good design hooks us emotionally, right?—tapping into what makes us all tick, making us laugh, cry, get upset, or at least click in the case of online application experiences.

The Trust part—thatmight be a kind of new, buzzy thing out there in Usability—and social media marketing—and an interesting word at that for the industry. But, no—even that’s not so new wave, next wave, or bleeding edge for Usability. An experience needs to constantly build our trust with each visual presentation of the interface, with each click and Ajaxy open-close interaction along the way. Any jarring bump in the road, any huge shift in the layout or color scheme, any misleading step in the flow—these can all make us, the users, decide against further participation in an experience. So, no … even Trust is a tried-and-true, classic fundamental of UX.

Even though the concepts may not be all Next Generation, I guess the PET TLA (Three-Letter Acronym) might be a cutesy way for us to remember to pay homage to the very core precepts of Experience Design and Usability. I guess it’s a good way for others to learn about our avocation. Let’s PET ‘em. P E T … Persuade, Emote, and Trust the User. P E T … the User P E T! Yay!

I felt that this marketing was very good. In this day and age, you must use persuasion to help consumers to make a decision.

Emotion and design are also very important. If you can catch the emotion of the consumer, it’s more likely they will buy into what you’re selling.

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