Hooked: How to Build Habit-Forming Products

by Nir Eyal

Forming habits is imperative for the survival of many products. As infinite distractions compete for our attention, companies are learning to master novel tactics to stay relevant in users’ minds. Amassing millions of users is no longer good enough. Companies increasingly find that their economic value is a function of the strength of the habits they create. In order to win the loyalty of their users and create a product that’s regularly used, companies must learn not only what compels users to click but also what makes them tick.

Habit-forming products start by alerting users with external triggers like an e-mail, a Web site link, or the app icon on a phone.

The investment phase increases the odds that the user will make another pass through the Hook cycle in the future. The investment occurs when the user puts something into the product of service such as time, data, effort, social capital, or money. However, the investment phase isn’t about users opening up their wallets and moving on with their day. Rather, the investment implies an action that improves the service for the next go-around. Inviting friends, stating preferences, building virtual assets, and learning to use new features are all investments users make to improve their experience. These commitments can be leveraged to make the trigger more engaging, the action easier, and the reward more exciting with every pass through the Hook cycle.

As companies combine their increased connectivity to consumers, with the ability to collect, mine, and process customer data at faster speeds, we are faced with a future where everything becomes potentially more habit forming.

Hooked seeks to unleash the tremendous new powers innovators and entrepreneurs have to influence the everyday lives of billions of people. I believe the trinity of access, data, and speed presents unprecedented opportunities to create positive habits. When harnessed correctly, technology can enhance lives through healthful behaviors that improve our relationships, make us smarter, and increase productivity.

Hooks connect the user’s problem with a company’s solution frequently enough to form a habit. My goal is to provide you with a deeper understanding of how certain products change what we do and, by extension, who we are.

Habits are defined as “behaviors done with little or no conscious thought.” The convergence of access, data, and speed is making the world a more habit-forming place. Businesses that create customer habits gain a significant competitive advantage. The Hook Model describes an experience designed to connect the user’s problem to a solution frequently enough to form a habit. The Hook Model has four phases: trigger, action, variable reward, and investment.

The evening version of my morning run had triggered a behavioral script that instructed my body to carry out my usual run-related activities—all without mindful awareness. Such is the nature of ingrained habits—behaviors done with little or no conscious thought—which, by some estimates, guide nearly half of our daily actions.

Users who continuously find value in a product are more likely to tell their friends about it. Frequent usage creates more opportunities to encourage people to invite their friends, broadcast content, and share through word of mouth. Hooked users become brand evangelists—megaphones for your company, bringing in new users at little or no cost.

“The most important factor to increasing growth is … Viral Cycle Time.”9 Viral Cycle Time is the amount of time it takes a user to invite another user, and it can have a massive impact. “For example, after 20 days with a cycle time of two days, you will have 20,470 users,” Skok writes. “But if you halved that cycle time to one day, you would have over 20 million users! It is logical that it would be better to have more cycles occur, but it is less obvious just how much better.”

Having a greater proportion of users daily returning to a service dramatically decreases Viral Cycle Time for two reasons: First, daily users initiate loops more often (think tagging a friend in a Facebook photo); second, more daily active users means more people to respond and react to each invitation. The cycle not only perpetuates the process—with higher and higher user engagement, it accelerates it.

But when it comes to shaking consumers’ old habits, these naive entrepreneurs often find that better products don’t always win—especially if a large number of users have already adopted a competing product.

A classic paper by John Gourville, a professor of marketing at Harvard Business School, stipulates that “many innovations fail because consumers irrationally overvalue the old while companies irrationally overvalue the new.”10 Gourville claims that for new entrants to stand a chance, they can’t just be better, they must be nine times better. Why such a high bar? Because old habits die hard and new products or services need to offer dramatic improvements to shake users out of old routines. Gourville writes that products that require a high degree of behavior change are doomed to fail even if the benefits of using the new product are clear and substantial.

users also increase their dependency on habit-forming products by storing value in them—further reducing the likelihood of switching to an alternative. For example, every e-mail sent and received using Google’s Gmail is stored indefinitely, providing users with a lasting repository of past conversations.

Companies that succeed in building a habit-forming business are often associated with game-changing, wildly successful innovation. But like any discipline, habit design has rules and caveats that define and explain why some products change lives while others do not. For one, new behaviors have a short half-life, as our minds tend to revert to our old ways of thinking and doing. Experiments show that lab animals habituated to new behaviors tend to regress to their first learned behaviors over time.12 To borrow a term from accounting, behaviors are LIFO—“last in, first out.” In other words, the habits you’ve most recently acquired are also the ones most likely to go soonest.

The enemy of forming new habits is past behaviors, and research suggests that old habits die hard. Even when we change our routines, neural pathways remain etched in our brains, ready to be reactivated when we lose focus.15 This presents an especially difficult challenge for product designers trying to create new lines or businesses based on forming new habits.

For new behaviors to really take hold, they must occur often. In a recent study at the University College London, researchers followed participants as they attempted to form a habit of flossing their teeth.16 As one of its findings, the study concluded that the more frequently the new behavior occurred, the stronger the habit became.

So why haven’t more Google users switched to Bing? Habits keep users loyal. If a user is familiar with the Google interface, switching to Bing requires cognitive effort. Although many aspects of Bing are similar to Google, even a slight change in pixel placement forces the would-be user to learn a new way of interacting with the site. Adapting to the differences in the Bing interface is what actually slows down regular Google users and makes Bing feel inferior, not the technology itself. Internet searches occur so frequently that Google is able to cement itself as the one and only solution in the habituated user’s mind. Users no longer need to think about whether or not to use Google; they just do.

By allowing users to comparison shop from within the site, Amazon provides tremendous perceived utility to its customers. Although shopping on Amazon may not occur as frequently as searching on Google, the company solidifies its place as the default solution to customers’ purchasing needs with each successful transaction. In fact, people are so comfortable comparison shopping on Amazon that they frequently use the company’s mobile app to check prices when standing in the aisles of real stores—often making a purchase from inside a competing retailer.

A company can begin to determine its product’s habit-forming potential by plotting two factors: frequency (how often the behavior occurs) and perceived utility (how useful and rewarding the behavior is in the user’s mind over alternative solutions). Googling occurs multiple times per day, but any particular search is negligibly better than rival services like Bing. Conversely, using Amazon may be a less frequent occurrence, but users receive great value knowing they’ll find whatever they need at the one and only “everything store.”

As represented in figure 1, a behavior that occurs with enough frequency and perceived utility enters the Habit Zone, helping to make it a default behavior. If either of these factors falls short and the behavior lies below the threshold, it is less likely that the desired behavior will become a habit.

A 2010 study found that some habits can be formed in a matter of weeks while others can take more than five months.23 The researchers also found that the complexity of the behavior and how important the habit was to the person greatly affected how quickly the routine was formed.

Let’s consider a few of today’s hottest consumer technology companies: Facebook, Twitter, Instagram, and Pinterest. What are they selling—vitamins or painkillers? Most people would guess vitamins, thinking users aren’t doing much of anything important other than perhaps seeking a quick boost of social validation. After all, think back to before you first started using these services. No one ever woke up in the middle of the night screaming, “I need something to help me update my status!” But like so many innovations, we did not know we needed them until they became part of our everyday lives. Before making up your mind on the vitamin versus painkiller debate for some of the world’s most successful tech companies, consider this idea: A habit is when not doing an action causes a bit of pain.

My answer to the vitamin versus painkiller question: Habit-forming technologies are both. These services seem at first to be offering nice-to-have vitamins, but once the habit is established, they provide an ongoing pain remedy. Seeking pleasure and avoiding pain are two key motivators in all species. When we feel discomfort, we seek to escape the uncomfortable sensation.

By progressing users through the four steps of the Hook Model—trigger, action, variable reward, and investment—hooks form habits.

Habit-forming products often start as nice-to-haves (vitamins) but once the habit is formed, they become must-haves (painkillers). Habit-forming products alleviate users’ pain by relieving a pronounced itch.

The association between an internal trigger and your product, however, is not formed overnight. It can take weeks or months of frequent usage for internal triggers to latch onto cues. New habits are sparked by external triggers, but associations with internal triggers are what keeps users hooked.

Finding customers’ internal triggers requires learning more about people than what they can tell you in a survey, though. It requires digging deeper to understand how your users feel. The ultimate goal of a habit-forming product is to solve the user’s pain by creating an association so that the user identifies the company’s product or service as the source of relief.

You’ll often find that people’s declared preferences—what they say they want—are far different from their revealed preferences—what they actually do.

tools like customer development,11 usability studies, and empathy maps12 are examples of methods for learning about potential users.

Triggers cue the user to take action and are the first step in the Hook Model. Triggers come in two types—external and internal. External triggers tell the user what to do next by placing information within the user’s environment. Internal triggers tell the user what to do next through associations stored in the user’s memory. Negative emotions frequently serve as internal triggers. To build a habit-forming product, makers need to understand which user emotions may be tied to internal triggers and know how to leverage external triggers to drive the user to action.

The trigger, driven by internal or external cues, informs the user of what to do next; however, if the user does not take action, the trigger is useless. To initiate action, doing must be easier than thinking. Remember, a habit is a behavior done with little or no conscious thought. The more effort—either physical or mental—required to perform the desired action, the less likely it is to occur.

Fogg posits that there are three ingredients required to initiate any and all behaviors: (1) the user must have sufficient motivation; (2) the user must have the ability to complete the desired action; and (3) a trigger must be present to activate the behavior.

Similar to MAO framework of consumer behaviour: motivation, ability, opportunity.

Fogg states that all humans are motivated to seek pleasure and avoid pain; to seek hope and avoid fear; and finally, to seek social acceptance and avoid rejection.

To increase the likelihood that a behavior will occur, Fogg instructs designers to focus on simplicity as a function of the user’s scarcest resource at that moment. In other words: Identify what the user is missing. What is making it difficult for the user to accomplish the desired action? Is the user short on time? Is the behavior too expensive? Is the user exhausted after a long day of work? Is the product too difficult to understand? Is the user in a social context where the behavior could be perceived as inappropriate? Is the behavior simply so far removed from the user’s normal routine that its strangeness is off-putting? These factors will differ by person and context; therefore, designers should ask, “What is the thing that is missing that would allow my users to proceed to the next step?” Designing with an eye toward simplifying the overall user experience reduces friction, removes obstacles, and helps push the user across Fogg’s action line.

Stephen Anderson, author of Seductive Interaction Design, created a tool called Mental Notes to help designers build better products through heuristics.13 Each card in his deck of fifty contains a brief description of a cognitive bias and is intended to spark product team conversations around how they might utilize the principle. For example, team members might ask themselves how they could utilize the endowed progress effect or the scarcity effect to increase the likelihood of a desired user behavior.

As described by Dr. B. J. Fogg’s Behavior Model: For any behavior to occur, a trigger must be present at the same time as the user has sufficient ability and motivation to take action. To increase the desired behavior, ensure a clear trigger is present; next, increase ability by making the action easier to do; finally, align with the right motivator. Every behavior is driven by one of three Core Motivators: seeking pleasure and avoiding pain; seeking hope and avoiding fear; seeking social acceptance while avoiding social rejection. Ability is influenced by the six factors of time, money, physical effort, brain cycles, social deviance, and non-routineness. Ability is dependent on users and their context at that moment.

Walk through the path your users would take to use your product or service, beginning from the time they feel their internal trigger to the point where they receive their expected outcome. How many steps does it take before users obtain the reward they came for? How does this process compare with the simplicity of some of the examples described in this chapter? How does it compare with competing products and services? Which resources are limiting your users’ ability to accomplish the tasks that will become habits? Time Brain cycles (too confusing) Money Social deviance (outside the norm) Physical effort Non-routine (too new) Brainstorm three testable ways to make intended tasks easier to complete. Consider how you might apply heuristics to make habit-forming actions more likely.

Ultimately, all businesses help users achieve an objective. As we learned in the previous chapter, reducing the steps needed to complete the intended outcome increases the likelihood of that outcome. But to keep users engaged, products need to deliver on their promises. To form the learned associations we discussed in chapter 2, the trigger phase, users must come to depend on the product as a reliable solution to their problem—the salve for the itch they came to scratch. The third step in the Hook Model is the variable reward phase, in which you reward your users by solving a problem, reinforcing their motivation for the action taken in the previous phase. To understand why rewards—and variable rewards in particular—are so powerful, we must first take a trip deep inside the brain.

Olds and Milner concluded that they had discovered the brain’s pleasure center. In fact, we now know other things that feel good also activate the same neural region. Sex, delicious food, a bargain, and even our digital devices all tap into this deep recess of the brain, providing the impetus for many of our behaviors.

The startling results showed that the nucleus accumbens was not activating when the reward (in this case a monetary payout) was received, but rather in anticipation of it. The study revealed that what draws us to act is not the sensation we receive from the reward itself, but the need to alleviate the craving for that reward.

Without variability we are like children in that once we figure out what will happen next, we become less excited by the experience. The same rules that apply to puppies also apply to products. To hold our attention, products must have an ongoing degree of novelty.

We are a species that depends on one another. Rewards of the tribe, or social rewards, are driven by our connectedness with other people. Our brains are adapted to seek rewards that make us feel accepted, attractive, important, and included.

Sites that leverage tribal rewards benefit from what psychologist Albert Bandura called “social learning theory.”8 Bandura studied the power of modeling and ascribed special powers to our ability to learn from others. In particular Bandura determined that people who observe someone being rewarded for a particular behavior are more likely to alter their own beliefs and subsequent actions. Notably, Bandura also demonstrated that this technique works particularly well when people observe the behavior of people most like themselves or who are slightly more experienced (and therefore, role models).

While variable content gets users to keep searching for interesting tidbits in their News Feeds, a click of the “Like” button provides a variable reward for the content’s creators. “Likes” and comments offer tribal validation for those who shared the content, and provide variable rewards that motivate them to continue posting.

The search for resources defines the next type of variable reward—the rewards of the hunt. The need to acquire physical objects, such as food and other supplies that aid our survival, is part of our brain’s operating system. Where we once hunted for food, today we hunt for other things. In modern society, food can be bought with cash, and more recently by extension, information translates into money.

The rewards of the self are fueled by “intrinsic motivation” as highlighted by the work of Edward Deci and Richard Ryan. Their self-determination theory espouses that people desire, among other things, to gain a sense of competency. Adding an element of mystery to this goal makes the pursuit all the more enticing.

1. Video Games Rewards of the self are a defining component in video games, as players seek to master the skills needed to pursue their quest. Leveling up, unlocking special powers, and other game mechanics fulfill a player’s desire for competency by showing progression and completion.

Although influencing behavior can be a part of good product design, heavy-handed efforts may have adverse consequences and risk losing users’ trust.

As part of a French study, researchers wanted to know if they could influence how much money people handed to a total stranger asking for bus fare by using just a few specially encoded words. They discovered a technique so simple and effective it doubled the amount people gave. The turn of phrase has not only proven to increase how much bus fare people give, but has also been effective in boosting charitable donations and participation in voluntary surveys. In fact, a recent meta-analysis of forty-two studies involving over twenty-two thousand participants concluded that these few words, placed at the end of a request, are a highly effective way to gain compliance, doubling the likelihood of people saying yes.24 The magic words the researchers discovered? The phrase “But you are free to accept or refuse.”