Hooked: How to Build Habit-Forming Products

by Nir Eyal

The researchers believe the phrase “But you are free” disarms our instinctive rejection of being told what to do. If you have ever grumbled at your mother when she tells you to put on a coat or felt your blood pressure rise when your boss micromanages you, you have experienced what psychologists term reactance, the hair-trigger response to threats to your autonomy. However, when a request is coupled with an affirmation of the right to choose, reactance is kept at bay. Yet can the principles of autonomy and reactance carry over into the way products change user behavior and drive the formation of new user habits?

I have not used Fitocracy for long, but it is easy to see how someone could get hooked. Fitocracy is first and foremost an online community. The app roped me in by closely mimicking real-world gym jabber among friends. The ritual of connecting with like-minded people existed long before Fitocracy, and the company leverages this behavior by making it easier and more rewarding to share encouragement, exchange advice, and receive praise. In fact, a recent study found social factors were the most important reasons people used the service and recommended it to others.

Companies fail to change user behaviors because they do not make their services enjoyable for its own sake, often asking users to learn new, unfamiliar actions instead of making old routines easier. Companies that successfully change behaviors present users with an implicit choice between their old way of doing things and a new, more convenient way to fulfill existing needs. By maintaining the users’ freedom to choose, products can facilitate the adoption of new habits and change behavior for good.

Yet if the search to resolve uncertainty is such a powerful tool of engagement, why do we eventually lose interest in the things that once riveted us? Many people have experienced the intense focus of being hooked on a TV series, a great book, a new video game, or even the latest gadget. However, most of us lose interest in a few days’ or weeks’ time. Why does the power of variable rewards seem to fade away?

As the Zynga story demonstrates, an element of mystery is an important component of continued user interest. Online games like FarmVille suffer from what I term finite variability—an experience that becomes predictable after use. While Breaking Bad built suspense over time as the audience wondered how the series would end, eventually interest in the show waned when it finally concluded. The series enthralled viewers with each new episode, but now that it is all over, how many people who saw it once will watch it again? With the plot lines known and the central mysteries revealed, the show just won’t seem as interesting the second time around. Perhaps this series might resurrect interest with a new spin-off show in the future, but viewership for old episodes people have already seen will never peak as it did when they were new.

Experiences with finite variability become less engaging because they eventually become predictable. Businesses with finite variability are not inferior per se; they just operate under different constraints. They must constantly churn out new content and experiences to cater to their consumers’ insatiable desire for novelty.

This is in contrast with companies making products exhibiting infinite variability—experiences that maintain user interest by sustaining variability with use. For example, games played to completion offer finite variability, while those played with other people have higher degrees of infinite variability because the players themselves alter the gameplay throughout. World of Warcraft, the world’s most popular massively multiplayer online role-playing game, still captures the attention of more than 10 million active users eight years after its release.31 FarmVille is played mostly in solitude, but World of Warcraft is frequently played with teams; it is the hard-to-predict behavior of other people that keeps the game interesting.

Variable reward is the third phase of the Hook Model, and there are three types of variable rewards: the tribe, the hunt, and the self. Rewards of the tribe is the search for social rewards fueled by connectedness with other people. Rewards of the hunt is the search for material resources and information. Rewards of the self is the search for intrinsic rewards of mastery, competence, and completion.

In chapter 1 we learned about the tooth-flossing study in which researchers determined that the frequency of a new behavior is a leading factor in forming a new habit. The study also found that the second most important factor in habit formation is a change in the participant’s attitude about the behavior.

Together, the three tendencies just described influence our future actions: The more effort we put into something, the more likely we are to value it; we are more likely to be consistent with our past behaviors; and finally, we change our preferences to avoid cognitive dissonance.

The Hook Model is not just a framework for changing one-time behaviors; it is a design pattern to create unprompted engagement in order to connect the user’s problem to the designer’s solution. To form the associations needed to create unprompted user engagement, something more than the three-step feedback loop is required.

The study found that the group given helpful computers performed almost twice as much work for their machines. The results showed that reciprocation is not just a characteristic expressed between people, but also a trait observed when humans interact with machines. Conceivably, we humans evolved the tendency to reciprocate kindness because it improved our species’ ability to survive. As it turns out, we invest in products and services for the same reasons we put effort into our relationships.

If users are not doing what the designer intended in the investment phase, the designer may be asking them to do too much. I recommend that you progressively stage the investment you want from users into small chunks of work, starting with small, easy tasks and building up to harder tasks during successive cycles through the Hook Model.

Pinterest clearly demonstrates the four stages of the Hook Model. It is a seamless flow: from the itch of the internal trigger that moves users to the intended action, through the variable reward, and finally to the investment, which also loads the next external trigger. Pinterest users move through the Hook cycle from beginning to end, then happily return to the starting point for another go-round.

Investments in a product create preferences because of our tendency to overvalue our work, be consistent with past behaviors, and avoid cognitive dissonance. Investment comes after the variable reward phase, when users are primed to reciprocate. Investments increase the likelihood of users returning by improving the service the more it is used. They enable the accrual of stored value in the form of content, data, followers, reputation, or skill. Investments increase the likelihood of users passing through the Hook again by loading the next trigger to start the cycle all over again.

You are now equipped to use the Hook Model to ask yourself these five fundamental questions for building effective hooks: What do users really want? What pain is your product relieving? (Internal trigger) What brings users to your service? (External trigger) What is the simplest action users take in anticipation of reward, and how can you simplify your product to make this action easier? (Action) Are users fulfilled by the reward yet left wanting more? (Variable reward) What “bit of work” do users invest in your product? Does it load the next trigger and store value to improve the product with use? (Investment)

the reward of portraying oneself in a positive light, also known as the humblebrag.4 A Harvard meta-analysis, “Disclosing information about the self is intrinsically rewarding,” found the act “engages neural and cognitive mechanisms associated with reward.”5 In fact, sharing feels so good that one study found “individuals were willing to forgo money to disclose about the self.”

after the designer has formulated new hypotheses, there is no way to know which ideas will work without testing them with actual users. Building a habit-forming product is an iterative process and requires user-behavior analysis and continuous experimentation.

Once you know how often users should use your product, dig into the numbers to identify how many and which type of users meet this threshold. As a best practice, use cohort analysis to measure changes in user behavior through future product iterations.

Naturally, now we do read books and newspapers over the Internet. When technologies are new, people are often skeptical. Old habits die hard and few people have the foresight to see how new innovations will eventually change their routines. However, by looking to early adopters who have already developed nascent behaviors, entrepreneurs and designers can identify niche use cases, which can be taken mainstream.

It is revealing that so many breakthrough technologies and companies, from airplanes to Airbnb, were at first dismissed by critics as toys or niche markets. Looking for nascent behaviors among early adopters can often uncover valuable new business opportunities.

Many companies have found success in driving new habit formation by identifying how changing user interactions can create new routines. Whenever a massive change occurs in the way people interact with technology, expect to find plenty of opportunities ripe for harvesting. Changes in interface suddenly make all sorts of behaviors easier. Subsequently, when the effort required to accomplish an action decreases, usage tends to explode.