Hooked by Nir Eyal – The compressed version

February 2, 2018

Hooked by Nir Eyal is a book on understanding behavioral designs. The Hook Model explained in the book, is a framework based on human psychology and a close examination of today's most successful habit forming prodcuts. Below are the notes that I took during my second read of the book. The notes have helped me revisit concepts whenever I needed. I am pleased to share with you my personal notes so that you can save time and also learn the Hook Model.

Pointers :  

1. The piece below includes all the concepts in the book, along with examples. 

2. It takes lot lesser to read this than actual book but be assured that you won't miss anything. 

3. While reading, do the activities listed in 'Do this now' OR do it at some point to better understand the Hook Model.

4. This is not a summary, and its fairly a long read. Read carefully and enjoy.




Through consecutive Hook cycles, successful products reach their ultimate goal of unprompted user engagement, bringing users back repeatedly, without depending on costly advertising or aggressive messaging. 

The four steps of the hook model provide the framework for creating a behavioural cycle for users – 

Trigger, is the actuator of behaviour

Action, done in anticipation of a reward

Reward, what user receives after taking an action and does more action to gain more rewards

Investment, where user invests in product (not in terms of money) to improve the service for future experience


Why forming habits are good 

Habits are behaviours done with little or no conscious thought.

Habits give us ability to focus our attention on other things by storing automatic responses in the basal ganglia (area of brain associated with involuntary action.

Reasons why forming habits are good for biz 

  1. Increase customer LTV (higher the engagement, higher CLTV)
  2. Price flexibility – once users get habituated to product, they are ready to pay a higher price OR turn a non paying user into paid user
  3. Engaged users become brand evangelist and invite more people to try the product. Higher the frequency of usage of a product, lower is viral cycle time (the time it takes the user to invite other users).
  4. Sharpening competitive edge – When a user has invested enough time in a product, they are unlikely to switch even if competition provides much more value.

Building mind monopoly 

If a product creates enough hooks for a user to repeat his behaviour, in very short period, the users are more likely to build habit for it. Eg. Google vs Bing, there is hardly any difference in terms of performance but users stick to what they get used to and learning a new interface is always challenged.

In the Habit Zone 


Product’s habit forming potential is determined by plotting 2 factors – frequency (how frequently a user is using the product) and perceived utility (how useful and rewarding the user finds the product with respect to competitive product).

Habits can not be formed outside habit zone.

Habit forming products alleviate user’s pain by relieving a pronounced itch.



  1. What habits your biz model requires
  2. What problems are users turning to your solve from ur product
  3. how do users currently solve that problem and why does it need a solution 
  4. Whats the expected frequency of ur product’s usage
  5. What user behaviour you want to make into habit



The triggers clearly tell the user what next action to take. They can be – External or Internal.

External triggers

The external triggers are the first step, which aim to get the user into the Hook model, so that they don't need external triggers for successive use of the product.

Types of external triggers – 

  1. Paid triggers – Advertising, search engines, and other paid channels. Habit forming companies don't rely on paid channels for too long, as its costly and unsustainable.
  2. Earned Triggers – Favorable press mentions, hot viral videos, features app on App Store. This can also prove to be short lived since this requires the product to be in limelight for an ongoing engagement, which is expensive.
  3. Relationship triggers – product referrals through social invites or word of mouth. This is highly effective but requires building an engaged user base that is enthusiastic about sharing product with others. Some products create dark patterns to trigger social shares unethically (e.g.. sending bulk invites). They might see initial surge in users but once users discover they have been duped, they will stop using the product.
  4. Owned triggers – These consume a small piece of real-estate in user’s environment. Eg. app icon on user’s phone screen, email newsletter that user has signed up for, app notification that user has allowed. This allows product to get a share of user’s attention. This trigger helps reengagement (unlike others which bring new users)

Internal triggers

When a product becomes tightly coupled with a thought, an emotion or a preexisting routine, it leverages internal trigger.

Emotions, particularly negatives ones, are powerful internal triggers, eg boredom, loneliness, frustration, confusion, indecisiveness. These create irritation and prompt almost instant action. Eg. Instagram lovers feel the fear of losing a moment if they fail to capture it. When a product solves user’s pain, it makes user feel positive emotions. This gradualy builds connection between user and the product. Users with depression tend to use internet more to seek the relief in form of building social connection, getting exciting news or online gaming for entertainment.

Building for triggers

To create habits, product designers must understand user’s internal triggers, which means the pain that the user is trying to solve. The product must build an association with the user so that he feels the product as a source of relief.

What users feel and what are their needs might not come across clear in a survey because users themselves are not very clear that what emotion dominates them. Their declared preferences (what they express) might be lot different from their revealed preferences (what they actually do). There is a difference in what people actually do and what they wish they did. Understanding the reasons why user took a certain action and what was his frame of mind at that time is IMP. Use 5 Whys to understand why user did what he did.

Prod designers must get into users shoes and write storing from their side, called user narratives.


  1. Who is your user ?
  2. Whats the user doing right before your intended habit?
  3. Come up with 3 internal triggers that could cue your user’s action 
  4. Which is internal trigger your users experience most frequently
  5. Whats the most frequent trigger and what is the habit you are designing for? Eg. When user (internal trigger), he (first action he takes)
  6. Based on what the user was doing right before taking the action, what can be possible placements of external triggers
  7. How can you couple external triggers with internal triggers
  8. What are the ways of external triggers you would like to use



Trigger informs the user what to do next, but if the user doesn’t take an action, trigger is useless. The more the effort (physical or mental) required to take the action, the lesser will be the chances of its occurrence.

3 ingredients to initiate action (Dr B.J. Fogg’s Behaviour model) – 

  1. user must have sufficient motivation 
  2. user must have ability to complete desired action 
  3. trigger must be present to activate the behaviour 

B = MAT (M=motivation, A=ability, T=trigger)

All 3 above ingredients must be present, in an adequate amount for the action to happen.


It is the energy for action. 3 core motivators drive the desire to act – 

  1. Seek pleasure, avoid pain 
  2. Seek hope, avoid fear
  3. Seek social acceptance, avoid rejection 

Advertisers mostly target to catch attention and motivate action. Eg. Budweiser uses social motivator by featuring 3 friends cheering. It displays that the brand goes together with good friends and good times.

The negative emotions like fear can also be powerful motivators. 

But sometimes user don't take actions as the product designers expect them to, even after right trigger is enabled and motivation is high. What is missing? – The ability of the user to take action easily.


Understand the reason why people use a product or service. Next, lay out the steps the customer must take to get the job done. Then, start removing steps until you reach the simplest possible process.

Any technology or products that significantly reduces the steps to complete a task, will enjoy high adoption rates.

Example : Initially dial-up internet connection seemed magical where user had to wait for modem to start and then be able to access internet. Now, with always available wifi, we have our emails instantly available. As the steps required reduced, the adoption increased.

Example : Blogger made the process of writing posts much easier and resulted in much higher number of posts. Then twitter came up with microblogging idea, as lot of people found blogging time consuming but they were fine posting short messages.

Elements of simplicity : To increase the likelihood of behaviour, minimise the elements of simplicity, at that time when user is intended to take action. 

  1. Time – how long it takes.
  2. Money – cost of taking action. 
  3. Physical effort – amount of labor involved 
  4. Brain cycles – level of mental effort and focus required
  5. social deviance – how accepted the behaviour is by others
  6. Non-routine – how much action matches or disrupts existing routines

Example : Login with Facebook, simplifies the process for many users. Though the users who are wary about their personal information shared, for them it triggers brain cycles of anxiety. There is no one size fits all solution.

Example : iPhone made it easier launching camera without unlocking phone, so that users don't miss a moment they want to capture. Pinterest made browsing easier with infinite scroll.


Motivation or Ability, which should you increase first?

Companies building technology solution, the greatest returns come from increasing product’s ease of use. The fact is, increasing motivation is expensive and time consuming. Users are often multitasking and have little patience for explanations about why or how they should do something. Influencing user by reducing effort is more effective than increasing someone’s desire to do the action. Make your product so simple that users already know how to use it, and you have got a winner.


On heuristics and Perception 

In Fogg’s terms, decreasing price increases user’s ability to take action. Though there are exceptions to this rule. 

What is Heuristics – the mental shortcuts we take to make decisions and form opinion.

Lets understand 4 of these brain biases (Heuristics), which can predict user’s actions. 

  1. The Scarcity Effect – The appearance of scarcity affects the perceived value of the product. Eg. a jar with 10 cookies vs a jar with 2 cookies (identical jars and cookies). People value the cookies that are less in number. Experiment – 2 set of people given 2 cookies in a jar and 10 cookies in a jar resp. The ones with 2 cookies, rated them much higher than other group. After this, people with 2 cookies, got 8 more and the other group got only 2. The group that started with 2 cookies and then went to 10, they rated cookies much lower than the other group. This proves that a product can decrease in perceived value if it starts off as scarce and becomes abundant.
  2. The Framing Effect – The perceived value of a product is a factor of where it’s placed and how it’s framed in user’s mind. Themind takes shortcut informed by our surroundings to make quick judgements. Eg. The same wine tasted better to participants when it costed 90$ vs when it costed 5$. 
  3. The Anchoring Effect – People often anchor to one piece of information when making a decision. Eg. A discounted product always feels cheaper even if a similar normal price product  is available at a cheaper price.
  4. The Endowed Progress Effect – This is a phenomenon that increases motivation as people believe they are nearing a goal. Eg. Linkedin showing progress bar for profile completion that starts with non-zero progress. This motivates people to progress further.

The above mentioned effects are one of the very few heuristic effects that product designers can utilise to build a behaviour. 


  1. Walk through the path your user takes to use your product starting from internal trigger to taking action and reaching expected outcome. How many steps did it take? Compare this with simplicity of examples mentioned above. How does it compare with existing competitive products.
  2. Which resources are limiting your users ability to take action – time, brain cycle, money, social deviance, physical effort, non-routine
  3. Come up with 3 ways to make intended task easier 
  4. Consider how you might apply heuristics to make habit-forming actions more likely


Whenever we receive pleasure from certain actions, a small area of brain, the nucleus accumbens, gets stimulated. Surprisingly, the nucleus accumbent doesn’t activate when the reward is received, but rather in anticipation of it. 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.

We start of with enjoying an action when we are not aware of the whole experience. As we do it more, the experience becomes less exciting. To hold ones attention, products too are required to have an ongoing degree of novelty.

Rewards of the Tribe, the Hunt, and the Self

Variability increases activity in nucleus accumbens and spikes levels of neurotransmitter dopamine, driving our hungry search for rewards. Variable reward can be found in any product and experiences. They fuel our drive to check emails, browse the web or bargain-shop. 

Types of variable rewards – the tribe, the hunt and the self.


Rewards of the Tribe – 

Rewards of 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. 

Most of the social media sites are based on this reward. People anticipate social validation for their posts. People who observe someone being rewarded for a particular behaviour, are more likely to alter their own beliefs and subsequent actions.

Eg. Logging in on Facebook, reveals the endless stream of content friends have shared, comments and like. The uncertainly of what users will find each time they visit, keeps pulling them back to the product. Additionally , Like and comments offer tribal validation. 

Eg. Stackoverflow, users write long, time consuming responses in anticipation of social rewards. Users upvote response when they like an answer and thus it moves to the top. When a user reaches certain points, they earn badges, which confer special status and privileges. The process of accumulating upvotes is highly variable.

Rewards of the Hunt – 

The need to acquire food, money, information is part of our brain’s operating system. 

Eg. Users keep on scrolling through Twitter feeds, in hunt of relevant information. 

Eg. Pinterest also uses infinite scrolls and shows users curated objects. The user never knows what he is going to see next. The design is such that when user reaches at the bottom of the scroll, he can see glimpse of upcoming posts (half cut images). This intrigues user more.

Rewards of the Self – 

These rewards we seek for a more personal form of gratification. The rewards of the self are furled by ‘intrinsic motivation’ as highlighted by the work of Edward Deci and Richard Ryan. Their self-determination theory espouses that people desire to gain a sense of competency. Adding an element of mystery to this goal makes the pursuit all the more enticing.

Eg. In Video games, the players seek to master the skills needed to pursue their quest . Leveling up, unlocking powers, acquiring adavnced weaponry, improve their character’s score etc fulfill the desire for competency by showing progression and completion. 

Eg We open our emails just to know if someone has sent us one. For many of us, the number of unread messages represents a goal to be completed. Mailbox helps users clean up their main inbox by moving emails to relevant folders, this gives users  feeling of completion and mastery.

Important considerations for Designing Reward System    

1. Variable rewards are not a free pass – 

Mahalo.com a question answer site offered a bounty for asking and answering a question. It initially caught a lot of attention from users but it started falling off eventually, as users stopped enjoying monetary benefits. Quora launched similar concept, though only offer social rewards. The users did not want to use earn money by answering questions. If earning money was their objective, they would find better ways. Also, the money rewards were coming far less frequently and were too small to stick to the product for money. However, Quora’s social reward proved far more frequent from users. Only by understanding what truly matters to the users, can a company correctly match the right variable reward to their intended behaviour. 

Gamifying experience through points, badges and leaderboards can prove effective, but only if they scratch the user’s itch. When there is a mismatch between user’s problems and company’s assumed solution, no amount of gamification will help spur the engagement. 

2. Maintain a sense of Autonomy

To improve user engagement, Quotra introduced feature which allowed users to know who viewed their answers. This proved intriguing to a lot of users. Though Quora automatically opted users without alerting them. This backfired as a lot of users were not willing to share their personal information like this. 

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

Autonomy is when the the product shows the user an action but the user still has the freedom to choose if he wants to do that. The “but you are free” technique demonstrated how we Are more likely to be persuaded to give when out ability to choose is reaffirmed. 

Eg. Myfitnesspal apps helps people lose weight by tracking their calorie in and out. The app is simple to use and does its job nicely. Though after some time, it becomes too much of a ask from an app to enter each and every meal. The reactance alarm of the user kicks in, and he stops using the app. On other hand, Fitocracy app does the same thing but it includes social motivation factor. So, right when the user reaches reactance level and feels like dropping off, he receives recognition from the community and this boosts his motivation to continue with the app.

Many companies build their products betting users will do what they make them do instead of letting them do what they want to do.The products should make old routines easier, and not asking users tp learn new, unfamiliar actions.

3. Beware of finite variability 

Television show ‘The Breaking BAd’ was recorded the highest rated TV show. The show utilised a simple formula to keep users tuning in. At the heart of every episode, there is a problem that the characters must solve. The characters face challenges and reach to the solution towards the end of the episode, at which time a new challenge arises to pique the viewer’s curiosity. The cycle of conflict, mystery, resolution and variability is the heart of good story telling. 

Yet with all the initial excitement, the excitement eventually fades away and we lose interest, why? Why does the power of variable rewards seem to fade away?

Eg. Zynga reached 83.8M active users on Farmville with their adoption of new users via Facebook. Soon they launched other similar games like CiteVille, FrontierVille and several more. But it turned out that Zynga’s new games were not really new to the users. This defines the concept of Finite Variability, which means an experience that becomes predictable after use. 

Businesses with finite variability must constantly churn out new content and experiences. The games played to a completion level offer finite variability while the games played online with other people, have higher degrees of infinite variability because the players themselves alter the gameplay throughout. Eg. World of Warcraft’s still receives 10M active users since its played with a team online.

Content consumption like TV shows are examples of finite variability, content creation is infinitely variable. Eg. sites like Dribble exemplify longer-lasting engagement. As the design patterns change, the designs shared on Dribble changes their pages, hence the variety is limitless.

4. Which rewards should you offer 

Variable rewards must satisfy user’s needs while leaving them wanting to reengage. Most habit-forming products utilise one or more types of reward – the tribe, the hunt, the self.

Eg. Emails have uncertainly, offering the hunt reward. emails have a social obligation to respond (rewards of tribe) . 


  1. Speak with 5 of your customers in an open ended interview to identify what they find enjoyable or encouraging about your product. Are there any moments of delight or surprise? Is there anything they find particularly satisfying about the product?
  2. Review the steps your customer takes to use your product. What outcome (reward) alleviates the user’s pain? Is the reward fulfilling or leave the user wanting more?
  3. 3 ways your product might heighten user’s search for variable rewards using – rewards of tribe (gratification from others), rewards of hunt (material goods, money, information), rewards of self (masterly, completion, competency or consistency)



For users to create mental association that activate their automatic behaviour, they must first invest in the product.

The frequency of a behaviour and participant’s attitude about the behaviour determine behaviour turning into habit. 

We irrationally value our efforts – When users invest time and effort into a product, they tend to value the product lot more.

We seek to be consistent with our past behaviour – A user asked to make a big investment might refuse the ask. While if the products ask to make small investments each time and that are in line, the users happily agree to the request. 

We avoid cognitive dissonance – When its too uncomfortable to get something, we change the perception of that thing in our mind and start feeling that its not worth the pain. We do this to avoid the pain of cognitive dissonance. Though, the perception can be changed gradually, which reduces the cognitive dissonance, and start changing our perception.

Together, these 3 tendencies, influence our future action – 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 effort; we change our preferences to avoid cognitive dissonance. 

These tendencies are also referred as ‘rationalisation’. We change our attitude and belief to adapt psychologically. 

The more time we spend in a product, we start believing that its worthwhile and then we don’t hesitate investing in it. 

Unlike in the action phase, investments are about the anticipation of longer-term rewards, not immediate gratification. Eg. Following someone on Twitter doesn’t give any stars or badges, it increases the likelihood of the user checking Twitter in the future. 

In investment phase the intended actions should be simple, though the product can expect the user to do bit of work but only after he has received reward. 

Storing value 

The stored value users put into the product, increases the likelihood they will use it again in future and comes in variety of forms. 

1. Storing content

Example : Every time iTunes users add song to their playlist, they are strengthening ties to the service. 

Example : Users create their digital life on Facebook by sharing photos or videos or status updates. The collection of memories and experiences becomes more valuable over time and service becomes harder to leave. 

2. Data – 

Example : On Linkedin the user’s online resume embodies the concept of data stored value. Every time job seekers use the service, they are prompted to add more information. 

If we can get user to enter just a little bit of information, they will be much more likely to return. 

Eg. Mint.com is a personal finance tool, which aggregates all of user’s accounts in one place, providing a complete picture of their financial life. Users can link accounts, categorise transaction or create a budget. The more data collected, the more the service’s stored value increases. 


Eg. Following users improves the quality of feed on Twitter, by including relevant posts. It also helps Twitter understand about the user which in turn improves the service overall. To increase followers on Twitter, user needs to create relevant and interesting tweets. This helps users reach larger audience, and no one wants to rebuild the loyal audience once they have worked hard to acquire them.

4. Reputation – 

On online marketplaces such as eBay, Taskrabbit, Yelp and Airbnb, people with negative scores are treated very differently than the ones with good reputation. It makes users, buyers and sellers, more likely to stick to whichever service they have invested their efforts in to maintain high-quality score. 

5. Skill – 

Invest time and effort into learning to use a product is a form of investment and stored value. Once a user has acquired skill, he moves to the right on the ability axis of Fogg Behaviour Model. 

Eg. Photoshop is a graphics editing tool, and it takes a lot of time to gain proficiency in using it. The skill learned on the platform can not be be translated to other applications, hence the users are less likely to switch. 

Loading the Next Trigger 

For habits to form, the users must use the product through multiple cycles of Hook model. External triggers are used to bring the users back to the product to start another cycle. 

Example: Any.Do is simple mobile task-management app. The app is designed for user to invest early on. The trigger comes in form of the app’s clear instructions on how to add and manage tasks. The reward comes in form of congratulatory message. The investment comes when the user allows Any.do to access his calendar. The app can now send notification post a meeting as reminder to complete to-dos. 

Example: Tinder, an online dating app, makes the investment easier (left and right swipe). This makes next trigger more likely. The more swipe, the more potential matches are made; and more match notifications are sent to both parties.

Example: Snapchat, a photo sharing app, is also a great means of communication. Every time users share pic, they load the next trigger. The sent message self-detracts after viewing, which implicitly prompts the user to respond.

Example: For Pinterest, like many social networks, the internal trigger is boredom. Once the user is on platform, the action is simple – scroll. The user makes investment by liking a pin, repining or commenting. This opens next trigger of notifying the user when someone interacts with the thread. 


  1. What ‘bit of work’ are your users doing to increase their likelihood of returning?

  2. Brainstorm 3 ways to add small investments in your product to : 
    1. Load next trigger
    2. Store value as data, content, followers, reputation and skill. 
  3. How long does it take for a ‘loaded trigger’ to reengage your users? How can you reduce the delay to shorten time spent cycling through Hook?


To help you as a designer of habit-forming technology, assess the morality behind how you manipulate users to follow the crafted experience. Determine your product’s morality on a manipulation matrix – facilitator, peddler, entertainer, or dealer.

  1. Facilitators use their own product and believe it can materially improve people’s lives. they have the highest chance of success because they most closely understand the users’ needs.
  2. Peddlers believe their product can improve people’s lives but do not use it themselves. They must beware of the hubris and inauthenticity that comes from building solutions for people they do not understand firsthand.
  3. Entertainers use their product but do not believe it can materially improve people’s lives. They can be successful but without making shelves of others better in some way, the entertainer’s products often lack staying power.
  4. Dealers neither use the product nor believe it can improve people’s lives. They have the lowest chance of finding long-term success and often find themselves in morally precarious positions.  


  1. Where you fall on manipulation matrix?
  2. Do you use your own product or service? 
  3. Does it influence positive or negative behaviours? 
  4. How does it make you feel? 
  5. Are you proud of the way you are influencing the behaviour of others?



Running your idea through the four phases of the model will help you discover potential weaknesses in your products habit-forming potential – 

  1. Does your users’ internal trigger frequently prompt them to action?
  2. Is your external trigger cueing them when they are most likely to act?
  3. Is your design simple enough to make taking the action easy?
  4. Does your reward satisfy the users’ need while leaving them wanting more?
  5. Do your users invest bit of work in the product, storing value to improve experience and loading the next trigger?


The hook model can be a helpful tool for filtering our bad ideas with low habit potential as well as a framework for identifying room for improvement in existing products.

Building habit forming product is an iterative process and requires user-behaviour analysis and continuous experimentation.

Steps to test a product on Habit Forming model – 

Step 1: Identify 

Define what it means to be a devoted user? How often should one use your product?

Once you know how often users should use your product, analyse how many and which type of users meet this threshold. Cohort analysis is best to measure changes in user behaviour.

Step 2: Codify

At least 5% of your users should qualify the devoted users. If its less than that, you need to revisit product-market fitment. 

If you have exceeded the bar, identify the habitual users and codify the steps they took using your product to understand what hooked them.

You are looking for a Habit Path – a series of similar actions shared by your most loyal users.

Step 3 : Modify

Once you have the insights, revisit your product and identify ways to nudge users down the same Habit Path taken by devotees. 

Discovering habit-forming opportunities

Studying your own needs can lead to remarkable discoveries and new ideas because the designed always has a direct line to at least one user: him or herself.

Joel Gascoigne, the founder of Buffer, decided to create it to solve his own need of a product to simplify the process of engaging on Twitter.

As you go about your day, ask yourself why you do or do not do certain things and how those tasks could be made easier or more rewarding.

Priyanka Gupta

Priyanka Gupta

Co-founder at IndiaBookStore
IITK alumnus, wandering soul. After seeking for job satisfaction in 4 firms over a span of 7 years, finally got her hands dirty in a startup. Dance freak, dreams to travel d world.
Priyanka Gupta

No Comments

Leave a Reply

Your email address will not be published. Required fields are marked *