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Summary: Hooked: How to Build Habit-Forming Products by Nir Eyal

A study of 150,000 people found that the average smartphone user unlocks their phone 110 times a day!

“79 percent of smartphone owners check their device within 15 minutes of waking up every morning.” – Nir Eyal

Why You’re Hooked to Your Smartphone

Smartphone Apps Provide Immediate Relief

  • When you feel bored, a list of interesting tweets or Instagram photos is one-click away.
  • When you feel uncertain, a list of Google search results is a few seconds away.
  • When you feel insignificant, you can tap the email icon on your phone to see a list of people who need you.


Your alarm wakes you and you stagger to the kitchen to brew a cup of coffee. You reach for your smartphone to map the traffic to work, check the weather and get an update on your friends. You perform these activities automatically, with little thought. Yet, if you find Keurig, or Facebook habit-forming, that’s not an accident. Getting you to incorporate its products and services into your habitual routine is the ultimate goal of every business. Consumer psychology expert Nir Eyal developed the “Hook Model” to put this brass ring closer to product developers’ grasp. He created his four-step model by researching the traits that successful products have in common, drawing insights from behavioral psychology and neuroscience, and extrapolating from his personal experience in gaming and advertising. While his model seems particularly apt for digital products, We recommend this user-friendly text to marketers, designers and entrepreneurs across product categories.

Book Summary: Hooked - How to Build Habit-Forming Products


  • Habits are behaviors you carry out with “little or no thought.”
  • Companies that produce habit-forming products reap multiple benefits.
  • The “Hook Model” is a four-step process marketers use to “hook” consumers.
  • The four phases of the Hook Model are “Trigger, Action, Variable Reward and Investment.”
  • External and internal triggers instruct people to perform a desired action.
  • People respond to triggers by acting in anticipation of a reward.
  • Variable rewards are unpredictable, intermittent rewards that satisfy a craving or solve a problem.
  • People are more likely to develop a habit around a product when they invest time or effort in using it.
  • Businesses exploit users’ pain by positioning products or services as oases of relief.
  • The “Manipulation Matrix” helps you analyze your motives for using the Hook Model.

Human beings have always felt bored, uncertain and insignificant, but thanks to our smartphones, we’ve never had a faster way to remedy these “negative” emotions.

Evan Williams, the co-founder of Medium and Twitter, tells us the formula he and other technology companies use is, “Take a human desire, preferably one that has been around for a really long time… and use modern technology to take out steps.”

“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.” – Nir Eyal

Smartphone Apps Offer Variable Rewards

“Simply giving users what they want is not enough to create a habit-forming product.” – Nir Eyal

Every time you pick up your phone you’re in for a surprise. There is a constant stream of new content coming your way via email, YouTube, Facebook, Twitter, and a dozen other apps. In a list of new content, you’re bound to find an interesting idea or photo worth liking. The frequency and variability of pleasurable content inside apps keep you hooked.

In the 1950s, psychologist B.F. Skinner put pigeons inside of a box. Inside the box was a button and every time the pigeons pecked the button, they received a food pellet. The pigeons learned to peck the button when they were hungry and to stop when they were satiated.

Then Skinner adjusted the food pellet dispenser so that sometimes the pigeons pecked the button and received a food pellet and sometimes they received nothing. Making the reward variable made the pigeons go insane. One pigeon pecked the button more than two times a second for 16 hours straight!

Sadly, human beings aren’t much different…

Smartphone Apps Get Us to Make Small Investments

“A psychological phenomenon known as the escalation of commitment has been shown to make our brains do all sorts of funny things. The power of commitment makes some people play video games until they keel over and die. It is used to influence people to give more to charity… The more users invest time and effort into a product or service, the more they value it.” – Nir Eyal

When you open the Instagram app for the first time, Instagram asks you to add a friend. Instagram makes adding people easy because they give you popular suggestions and offer to scan your Facebook and Contact list. Instagram knows when you make the small investment needed to add one person to your Instagram account you are more likely to return to the app when they send you a notification.

The more often you return to an app, the more you invest in an app, and the more likely you are to form a mindless app checking habit.

How to get UNHOOKED

Make it harder to check your phone:

  • Put a long password on your phone, so it takes time to unlock it.
  • Put your phone in a drawer under a stack of papers while you work.
  • Put your phone in another room when you go to sleep.

Turn off all non-essential app notifications. The only app notifications on my phone are to-do list reminders and calendar events. If an application can’t buzz, ding, or flash messages at you, that app is less likely to get you to use it.

When you understand how product developers design apps to hook you, and what you can do to unhook yourself, you are well on your way to reclaiming your ability to focus and being more productive.


Habit-Forming Products

You carry out habitual behaviors with “little or no thought,” but when your use of a product or service – like a smartphone or Twitter – becomes a habit, the company behind it scores a meaningful win. Marketers try to engineer the customer experience so that it becomes ingrained because a product’s success requires loyal, habitual users. Smartphones, tablets and game consoles give consumers around-the-clock access and connectivity. Marketers have two tools – that constant entrée and detailed personal information gleaned through data mining – for propelling the buyer behavior that most benefits them: Forming a habit.

The Habit Advantage

Investors calculate a company’s “customer life-time value” (CLTV) to determine its overall value. CLTV is the amount of money a business expects to make from a single customer during his or her lifetime. The more habit-forming a product is, the higher its CLTV. As consumers incorporate a product into their daily lives, they become less resistant to increases in its price. Loyal users tell their friends about products they routinely enjoy and recommend them via social networks. Word-of-mouth advertising is credible and cheap.

“Like all technologies, recent advances in the habit-forming potential of digital innovation have both positive and negative effects.”

Companies marketing habit-forming offerings stave off competition. New entrants find it difficult to change buyers’ embedded behaviors, even when they produce a superior product. For example, keyboards still use the QWERTY configuration, designed in the 1870s for the first typewriters. Better layouts come to market, but they don’t catch on. Once people become proficient at touch typing on a QWERTY keyboard, they are loath to learn a new, even if more efficient, system.

“The technologies we use have turned into compulsions, if not full-fledged addictions.”

The “Habit Zone” is the sweet spot between the frequency of a behavior and its “perceived utility,” the ease and convenience of continued use. Products and services fall into two metaphorical categories: “vitamins and painkillers.” Vitamins are nice-to-have, satisfying products that users can live without. People feel good about taking vitamins but don’t feel terrible if they miss a day. People feel pain if a painkiller-category product is out of reach. When something becomes a habit, doing without it hurts. For example, some consumers can’t imagine a morning without coffee or a day without Twitter.

The “Hook Model”

All businesses can use a four-step process – the Hook Model – to “hook” consumers on their offerings. People who become hooked will use that offering repeatedly, making advertising and marketing less necessary. The four phases of this model are:

1. “Trigger: The Actuator of Behavior”

Triggers spark your behavior. They’re cues telling people what action to take. Triggers are either external or internal. When you see, smell, taste, hear or touch an external trigger, it prompts a reaction and points clearly toward a particular act. For example, the login button on a home page is an online trigger. External triggers fall into four categories:

  • “Paid” – Advertising consists of paid triggers. Companies buy advertising to attract new users to convert them into loyal customers.
  • “Earned” – Companies invest time and energy to secure earned triggers. Publicizing an event or producing a video in hopes that it will go viral are earned triggers.
  • “Relationship” – Word-of-mouth recommendations from one person to another, or via social networks, are relationship-based triggers.
  • “Owned” – With a user’s permission, a company could provide reminders. For example, a smartphone owner might permit an app company to send an upgrade notice about its app.

“Hooked users become brand evangelists – megaphones for your company, bringing in new users at little or no cost.”

Internal triggers are subconscious associations between an action or thought and an emotion. Thus, boredom makes you check your email. People form habitual reactions in response to the “tiny stressors” they experience through the day. Businesses exploit users’ pain by positioning products or services as oases of relief. Consumers habitually reach for products and services that provide comfort or solve their problems. Businesses must understand the internal triggers that cause people to use their products so they can tailor external triggers that propel users to engage.

2. “Action: The Behavior Done in Anticipation of a Reward”

Action is what a trigger seeks to spur. An action is how you behave because you expect an award. In the context of habits, people act instinctively, with almost no deliberate thought. Dr. B.J. Fogg conducted research at Stanford University to determine what instigates people to act. You can express his “Fogg Behavior Model” in the formula “B=MAT” – that is, “Behavior” occurs in the presence of sufficient “Motivation,” and “Ability” plus “a Trigger.” For example, you hear your cellphone ring. If you buried it at the bottom of your handbag or briefcase, you may let the call go to voice mail. Perhaps your phone is set on silent and you never hear the ring. Some element of the formula is weak or missing, preventing an action from taking place.

“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.”

Fogg groups human motivators into three broad categories: “To seek pleasure and avoid pain; to seek hope and avoid fear; to seek social acceptance and avoid rejection.” Advertising capitalizes on these motivators. Sexual images in ads, such as beautiful actresses promoting, provide the promise of pleasure. Shots of men gathering to drink Budweiser and cheer for their team demonstrate social acceptability.

“Only by understanding what truly matters to users can a company correctly match the right variable reward to their intended behavior.”

The actions that form habits require little or no mental effort. The action the trigger elicits should manifest its simplest form. Several successful digital networks, such as Twitter, Facebook and Google, recognized the importance of making the user experience as simple as possible. Evan Williams, one of the founders of Twitter and Blogger, summarized this approach. “Take a human desire, preferably one that has been around for a really long time…Identify that desire and use modern technology to take out steps.” Conducting a search on Google requires little time or effort. The ease of taking a photo with an iPhone made it the popular choice.

“Companies increasingly find that their economic value is a function of the strengths of the habits they create.”

Simplifying the decision-making process through “heuristics” or “mental shortcuts” increases the habit-forming nature of your offering. Marketing heuristics include insinuating scarcity, putting items on sale and shaping the sales environment to create an appropriate context.

3. “Variable Reward: The Hook’s Ability to Create a Craving”

Craving is how the Hook Model builds your desire. Once people act, they experience the relief of having their problem solved or their urge satiated. Research into reward behavior shows that anticipation of an award activates the brain’s nucleus accumbens, or pleasure center. However, as people come to expect rewards, incentives begin to lose their allure. Introducing variable payoffs – that is, unexpected or intermittent rewards – revives activity in the brain’s pleasure center.

“Hooks can be found in virtually any experience that burrows into our minds (and often our wallets).”

Variable awards fall into three types: “the tribe, the hunt and the self.” Tribe rewards tap into the desire to connect socially and to feel included. Social media sites such as Pinterest, Facebook and Twitter, and computer games such as League of Legends, deftly exploit this universal craving. People visit Facebook repeatedly to see if their friends “like” their posts. League of Legends players set out to earn “honor points” in recognition of their fair conduct.

“Ubiquitous access to the web, transferring greater amounts of personal data at faster speeds than ever before, has created a more potentially addictive world.”

Hunting for food and shelter is a deep-seated human behavior, so hunt rewards are satisfying. Gambling online or scrolling through Pinterest provides rewards associated with gathering “resources or information.”

People feel compelled to overcome obstacles; that self-rewards them in the form of feelings of accomplishment and performance satisfaction. Playing video games is an obvious expression of this need. However, few products offer “infinite variability.” Even the most popular, exciting offerings become commonplace with use and repetition. Keeping variable rewards fresh requires the continuous input of new ideas, experiences and content.

4. “Investment: The User Does a Bit of Work”

When you put in effort, you become more committed to your purchase. People are more likely to develop a habit around a product or service when they invest in its use. Even small investments of time or energy forge strong bonds. For example, IKEA knows that customers love their furniture more when they assemble it, than when they purchase it ready-made.

“Unfortunately, too many companies build their products betting users will do what they make them do instead of letting them do what they want to do.”

Once people commit to a behavior, they’re more likely to repeat it in the future. For example, people may at first be reluctant to erect a sign in their yard promoting a political candidate, but after the initial time, their resistance drops substantially.

People avoid “cognitive dissonance,” the need to revise an established perception to fit into a comfortable context. The fable of the fox declaring grapes too sour when he couldn’t reach them is a classic example of cognitive dissonance. In terms of product investment, people are willing to try something other people enjoy, such as drinking coffee or alcohol, even if their first taste is unpleasant.

“The more users invest in a product through tiny bits of work, the more valuable the product becomes in their lives and the less they question its use.”

The more time and energy users invest in a product, the more likely they are to keep using it. The accrual of “stored value” in the form of “content, data, followers, reputation and skill” keeps them hooked. For example, once people build a music library on iTunes, they’re reluctant to leave and begin again with another provider. When users post their résumés on LinkedIn and add data to their profiles, they are unlikely to switch to another site. People work to build a good reputation on sites such as eBay, TaskRabbit and Airbnb. Once they’ve achieved a high rating, they’re averse to giving it up.

“The more effort – either physical or mental – required to perform the desired action, the less likely it is to occur.”

The Hook Model is circular – embedded external triggers encourage users to return, strengthening their habits. Pinterest demonstrates the four phases of the Hook Model in operation. First, the site offers a distraction from boredom by displaying a variety of appealing images. New users enjoy browsing; they experience social connection by commenting and posting images. As they pin images, their investment of time engenders loyalty; their stored value keeps them clicking. When other people contribute or comment on their posts, that provides an external trigger that retains users through another cycle.

Assess and Follow Up

Advances in neuroscience, coupled with technology-enabled connectivity and big-data mining, make marketing’s behavior-changing techniques more targeted and effective. If you use the Hook Model, examine your motivations to make sure your purposes are altruistic and that you are not exploiting others for your own advantage.

“Without variability we are like children in that once we figure out what will happen next, we become less excited by the experience.”

The “Manipulation Matrix” is a four-quadrant chart that helps you analyze your motives for using the Hook Model. Which quadrant describes you?

  • “The Facilitator” – Creators who believe their product or service makes a positive contribution and who would use it themselves.
  • “The Peddler” – Sellers who believe their product has value, but may not use it themselves. Advertising is an example of peddling.
  • “The Entertainer” – It doesn’t damage anyone to create art and distraction for people’s enjoyment, but entertainment is a “hits-driven” business.
  • “The Dealer” – Manipulators who use their offerings as a way to make a buck.

“The products and services we use habitually alter our everyday behavior, just as their designers intended.”

Assess whether your offering has habit-forming potential by testing your idea against the Hook Model. Continually evaluate your hook tactics to review how you perform. Experiment with new ideas and strategies, and analyze how well they promote the user behavior you hope to elicit. Use the three-step “Habit Testing” process for your analysis. First, consider how often you expect a typical customer to use your product, and what comprises either normal or excessive usage. Next, categorize this use by estimating how many users you need to make your business successful. Then, modify your tactics to turn casual users into devotees with a habit.

About the author

Nir Eyal is a video-gaming industry and advertising veteran. He writes, speaks and teaches about applied consumer psychology.


In his book “Hooked: How to Build Habit-Forming Products”, Nir Eyal outlines a framework for designing habit-forming products and services. Eyal draws from scientific research on habits, motivation, rewards and addiction to break down exactly how products like Facebook, Instagram and countless apps manage to form habits and gain loyal, repeated and long-term use.

The central thesis of the book is that by understanding habit formation and applying techniques from behavioral psychology, product designers can intentionally and ethically create products that people want to use regularly and don’t want to stop using. Eyal presents a four-step “Hook Model” that maps out how individual user experiences can be designed to create habits over time through a cycle of triggering actions, performing an action and receiving a reward that motivates future use.

In the opening chapters, Eyal establishes the importance of understanding habits and how they form. He defines habits as behaviors that are repeated regularly through forming strong association between contextual cues (triggers) and responses. Habits require little conscious thought or effort as they become automated through repetition. Eyal delves into neurological and behavioral research that shows how habits are formed through reinforcement in the brain’s reward system. Repeatedly cueing a response and providing an enjoyable reward strengthens neural pathways over time to the point a behavior is repeated almost automatically when the cue is encountered.

Eyal then outlines the four key steps in the “Hook Model” that products can leverage to form habits: trigger, action, variable reward and investment. First, a trigger must activate the user and cue the desired behavior, such as receiving a push notification, opening an app icon or seeing social media updates from friends. Second, the triggered user performs an action within the product, like checking their notifications, scrolling their feed or posting an update. Third, the user receives a reward in response, such as likes, comments or finding interesting new content – this reward must be unpredictable and variable to keep the user engaged. Finally, the user invests further effort back into the system to continue the cycle, whether posting more, connecting with others or customizing their experience.

By thoughtfully designing each step, products can exploit psychological weaknesses and turn casual uses into repetitive habits. Trigger mechanisms cue users at optimal moments, actions are made easy and rewarding, while unpredictable variable rewards keep the motivation strong. Additional investments of time, data or social bonds deepen user engagement over prolonged use. This cycle repeats unconsciously over time as habits are automated through strengthened neural pathways.

A key part of Eyal’s framework is separating repeat behaviors driven purely by utility or enjoyment, versus those formed through habit-triggering design. Not all repetition indicates a true habit. Outlining how dopamine-releasing rewards drive the plasticity underlying habit formation provides valuable neuroscientific validity to Eyal’s approach. It helps explain the addictive power of platforms constantly optimized to trigger, reward and invest users while appearing engaging and beneficial on the surface.

However, Eyal is also careful to argue habit-forming design should be implemented ethically when possible. Transparency around intent and acknowledgment of potential downsides is advocated. Designing for moderation rather than addiction is suggested, such as through increased friction or nudges toward healthier habits. While businesses understandably seek loyal users and profits, balancing habit-driven engagement with user well-being and consent is highlighted as an important consideration.

Overall, “Hooked” provides a compelling framework backed by scientific research yet practical for designers. The four-step model concisely maps out how individual experiences accumulate into durable habits over the long run. Real-world examples help illustrate how major platforms activate this cycle and turn fleeting interest into repetitive usage patterns. Business implications are also discussed, from focusing on retention instead of conversions to optimizing user journeys based on habit-triggering principles.

Though manipulation of human psychology for profit raises ethical concerns addressed thoughtfully by Eyal, the framework remains illuminating for both designers and users. With awareness of how subtle triggers and variable rewards can drive unconscious adoption of habits, more informed choices may be possible regarding personal technology use and design of interactive products and services. “Hooked” achieves the goal of demystifying core drivers of compulsive usage in a way that retains rigor, honesty and practical applicability. It stands as a valuable resource for both understanding and thoughtfully leveraging the habits underlying our modern digital relationships and experiences.

In summary, Nir Eyal presents a compelling framework grounded in science for how individual experiences can accumulate into self-reinforcing habits over time. By understanding triggers, actions, rewards and investments, designers can intentionally create products optimized for long-term engagement and retention. While acknowledging potential issues, Eyal’s guidelines in “Hooked” remain illuminating for both designing and using technology in a well-informed manner.


“Hooked: How to Build Habit-Forming Products” by Nir Eyal is an essential read for product designers, entrepreneurs, and anyone interested in understanding the psychology behind habit formation. Eyal’s four-step “Hook Model” provides a practical framework to create engaging products that keep users coming back. The book’s strengths lie in its research-based approach, real-world examples, and user-centric focus. However, it is worth noting that the book’s scope is primarily focused on digital products, and readers seeking a more in-depth exploration of ethical considerations may find it lacking. Nonetheless, “Hooked” offers valuable insights and strategies that can help shape the future of product design.

Alex Lim is a certified book reviewer and editor with over 10 years of experience in the publishing industry. He has reviewed hundreds of books for reputable magazines and websites, such as The New York Times, The Guardian, and Goodreads. Alex has a master’s degree in comparative literature from Harvard University and a PhD in literary criticism from Oxford University. He is also the author of several acclaimed books on literary theory and analysis, such as The Art of Reading and How to Write a Book Review. Alex lives in London, England with his wife and two children. You can contact him at [email protected] or follow him on Website | Twitter | Facebook

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