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Hooked by Nir Eyal - Book Notes, Summary, Review

Hooked by Nir Eyal - Book Notes, Summary, Review - Cover Image

Published: March 19, 2021

Reading Time: 14 min


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Hooked by Nir Eyal outlines The Hook Model, a methodology for building habit forming products that improve a user’s life in some way.

I found this to be a very interesting and informative book with lots of new concepts and terms related to marketing and product design.

There’s something here for those working in the world of product design as well as outside observers.

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Who Should Read This Book?

I would recommend this book to designers and to people working in product creation.

For these people, there is a lot of advice about how to build products and services that fit a user’s needs which in turn will result in the frequent use of that product or service.

I would also recommend this book to people interested in the world of product design and marketing.

As someone who isn’t very knowledgeable on marketing and marketing tactics, I learned a lot about how these tactics can be used in negative ways.

Terms like CLTV (Customer Lifetime Value) and viral cycle time were new to me and definitely rubbed me up the wrong way.

How This Book Changed Me

By reading this book through the eyes of a consumer, I learned a lot about the potential negative ways products or services can be designed to make them addictive to users.

I’m hoping this will help me to be more mindful of how I use apps, products, and services in the future.

As I mentioned above, terms like Customer Lifetime Value sounded very cold and unfeeling to me. I don’t like the idea of being referred to as a number or a value to some big company.

With that in mind, I’ll definitely be paying more attention to how things are designed to see if the Hook Model is being used in positive or negative ways to influence me.

As a web designer / UI designer, I learned a lot about the benefits of applying the Hook model when designing apps.

Making use of this model can be a force for good to ultimately improve a user’s life.

My Top 3 Quotes That Resonated With Me

“Seeking pleasure and avoiding pain are two key motivators in all species. When we feel discomfort, we seek to escape the uncomfortable sensation.” p29

“The Hook Model is designed to connect the user’s problem with the designer’s solution frequently enough to form a habit. It is a framework for building products that solve user needs through long-term” p115

“Building a habit-forming product is an iterative process and requires user behavior analysis and continuous experimentation”. p134

Book Notes


  • The Hook Model - a four-phase process companies employ to encourage habit-forming behaviors towards their product/service.
  • Over repeated cycles of the Hook Model, users are encouraged to come back to the product or service repeatedly without the need for advertising or aggressive notifications. They develop the habit and will return to the product or service without thinking.
  • Habits are learned behaviors done with little or no conscious thought.
  1. Trigger
    • This is the thing that sparks a user’s behavior. It’s like the spark plug in an engine.
    • Triggers can be internal and external
    • Internal triggers are things inside of the person like motivations, mental models etc.
    • External triggers are things in the world that alert people
  2. Action
    • This is the behavior that’s done in anticipation of a reward.
    • If the action is easy to do and holds enough motivation for a user, they’ll be more likely to perform that action.
  3. Variable Reward
    • A reward awaits the user when they perform an action. Whether it be seeing the latest updates on Twitter or the newest YouTube video from our favorite channel.
    • When we’re awaiting the reward, our levels of dopamine surge as we anticipate it.
    • Over time, this might get a bit predictable; that’s where the variable reward comes in. When the reward is varied, we don’t know exactly what to expect. This increases our dopamine levels even further increasing our desire for the reward.
  4. Investment
    • When a user invests time, money, effort, data into a product or service, they’re more likely to repeatedly use it and less likely to switch to an alternative.
    • It ensures that the user will pass through the Hook cycle repeatedly.
    • An investment is made by the user to make the product or service better the next time they use it.

1 The Habit Zone

  • Habits allow us to subconsciously do things so that we can focus our attention on other things.
  • Most of our daily behaviors are done out of habit. How many times have you driven to work only to realize that you don’t remember the trip to work?
  • CLTV - Customer Lifetime Value - this seems like quite a cynical and cold term but it’s the amount of money made from a customer before they stop using the product, switch to another product, or die..
    • User habits can increase the CLTV so they are essential to consider when designing a product or service.
    • Think of how video games will allow you to play for a certain period of time. Long enough to enjoy it, then they ask you to pay for money to unlock certain features to continue. If you’ve been playing the game for long enough and have enjoyed it, you’re more likely to pay to unlock those features.
    • This whole thing rubs me up the wrong way and it really deters me from playing certain games or using certain apps!
  • Viral Cycle Time - the amount of time it takes a user to invite another user.
  • Our ingrained habits make it difficult to change unless we have a strong enough motivation to do so.
    • Imagine trying to switch from QWERTY to Dvorak.
    • The same is true for switching a product or service.
  • In order to form a new habit, we must do it often and it shouldn’t cause us to much difficulty (perceived utility).
    • If a behavior occurs often enough and it provides enough value, it enters what’s called the Habit Zone. This, over time, will help to create a habit. If it doesn’t meet this threshold, we’re less likely to form the habit.
    • Habits can take weeks or months to form depending on the habit.

“Seeking pleasure and avoiding pain are two key motivators in all species. When we feel discomfort, we seek to escape the uncomfortable sensation.” p29

2 Trigger

  • Triggers are cues to perform a habit. They move us to take action.
  • They can be internal or external
  • External triggers:
    • These are physical things in our environment for example, a button, a log in prompt.
    • It’s important to remember that too much choice can cause hesitation. “The Paradox of Choice”.
    • Types of External Triggers:
      • Paid Triggers - Advertising and marketing
      • Earned Triggers - Mentions, viral videos, being featured on the app store
      • Relationship Triggers - word of mouth referrals
      • Owned Triggers - an app icon, an email newsletter, app update icon
    • Dark Patterns - unethical ways of exploiting people’s triggers.
    • The goal of external triggers is to move the user into the Hook Model. They can then form habits that are cued by internal triggers
    • External triggers are what hook users but internal triggers are what keep them hooked.
  • Internal triggers:
    • These are triggers that are in your mind that relate to thoughts, emotions, or pre-existing behaviors.

    “As product designers, it is our goal to solve these problems and eliminate pain — to scratch the user’s itch. Users who find a product that alleviates their pain will form strong, positive associations with the product over time. After continued use, bonds begin to form — like the layers of nacre in an oyster — between the product and the user whose need it satisfies. Gradually, these bonds cement into a habit as users turn to your product when experiencing certain internal triggers.” p38

    • Fear is a powerful internal trigger
      • Social networking sites leverage the user’s fear of missing out to keep them hooked.
  • The 5 Whys Method - by repeating why five times, the nature of the problem as well as the solution becomes clear.

3 Action

  • The more effort required to perform an action, the less likely it is to occur. Easier often equals better.
  • “Motivation is the energy of action” - Dr. Edward Deci, Professor of Psychology
  • By removing the obstacles that stand in the way of a user completing an action, we create a simple to use product.

    “the greatest return on investment will generally come from increasing a product’s ease-of-use.” p59

  • There are a number of cognitive biases that influence our behaviors, most of which we are completely unaware of:
    • The Scarcity Effect
      • Was researched in 1975 - by researchers Worchel, Lee, Adewole
      • The appearance of scarcity influences our perceived value of something.
      • If something is scarce in supply, it might be because others know something you don’t.
        • Consider the toilet roll shortages at the start of the pandemic.
    • The Anchoring Effect
      • For example, buy one get one free and similar marketing tactics
      • People often anchor to one piece of information when making a decision. It’s worth considering if it’s actually better value to buy something because it’s on sale vs something similar that’s not on sale.
    • The Endowed Progress Effect
      • Our motivation increases when we think we are nearing a goal
  • “Heuristics are cognitive shortcuts we take to make quick decisions.”

4 Variable Reward

  • It’s not the reward itself that compels us to perform an action, it’s the desire for the reward.
  • Once we become familiar with what will happen next, we become bored.
  • To prevent this boredom and to hold our attention, products should have some novelty or variable reward.
  • Because habits are things we do without much thought, when we encounter something outside of that norm, we pay attention to it.
  • There are 3 types of variable rewards:
    1. Rewards of the Tribe - social rewards.
      • We’re often motivated by wanting to be connected to others so we seek the approval and acceptance of others.
      • Being connected with others via social media offers this interaction with others.
      • We become hooked on what updates from others we’ll find when we refresh our feed. We don’t know what to expect so we keep coming back for more.
    2. Rewards Of The Hunt
      • The feed (Twitter, Facebook, Reddit) is this reward in action.
      • We are compelled to hunt for new, exciting, fun things throughout our feed which is why we can end up endlessly scrolling for ages without realizing.
    3. Rewards Of The Self
      • Rewards we seek to make us happier or more satisfied.
      • We are motivated to see something through to completion as it gives us personal satisfaction.
      • Video games are a great example of this. We look to master the skills needed in a game to complete missions. Leveling up, skill trees etc. show our progression and fulfil our desire for completion.
  • Gamification is a popular concept in apps, products, services.
    • These apps make use of gaming elements (points, leaderboards etc.) to motivate and entice users.
    • It is not a one-size fits all solution though. Rewards must align with the user’s internal motivations
  • Products or services that are too heavy handed with marketing tactics will lose a user’s trust.
  • Users want to feel that they are making their own decisions.

“In a phenomenon called “experience-taking,” researchers have shown that people who read a story about a character actually feel what the protagonist is feeling. As we step into the character’s shoes we experience his or her motivations — including the search for rewards of the tribe, hunt and self. We empathize with characters because they are driven by the same things that drive us.” p90

5 Investment

  • To become more used to a product, a user needs to invest in it.
    • Types of investments include time, effort, money, data.
    • The more you invest in something, the more value you put in it.
  • By adding something of value to the product, users increase the chances of repeated use of that product.
  • Once a user has made a sufficient investment in a product, it becomes very difficult to switch to a different product.

6 What Are You Going To Do With This?

“The Hook Model is designed to connect the user’s problem with the designer’s solution frequently enough to form a habit. It is a framework for building products that solve user needs through long-term” p115

The Five fundamental questions for building effective hooks:

  1. What do users really want? What pain is your product relieving? (Internal Trigger)
  2. What brings users to your service? (External Trigger)
  3. What is the simplest action users take in anticipation of reward, and how can you simplify your product to make this action easier? (Action)
  4. Are users fulfilled by the reward, yet left wanting more? (Variable Reward)
  5. 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 ability to change people’s behaviors can be a force for good but it can also be used in negative ways. This is important to consider and it’s the responsibility of the creators to use this responsibly.
    • One way to understand your business model and how it fits in with the Hook Model is with the Manipulation Matrix.
    • Ask yourself: “Would I use the product myself?” and “will the product help users materially improve their lives?”

The Manipulation Matrix:

  • The Facilitator
    • You are creating something that you would use and that you believe makes the user’s life better.
  • The Peddler
    • You are creating something you wouldn’t use that you believe makes the user’s life better.
    • Creating something that provides value to others that you wouldn’t use yourself is difficult. It’s hard for you to connect with your users.
    • As a result the product lacks empathy and isn’t useful.
  • The Entertainer
    • You are creating something that you would use but doesn’t make the user’s life better.
    • You are making entertainment.
  • The Dealer
    • You are creating something you wouldn’t use that doesn’t make the user’s life better
    • This is exploitation. It’s likely the creator is only in it for the money.

8 Habit Testing

“Building a habit-forming product is an iterative process and requires user behavior analysis and continuous experimentation”. p134

  • Habit testing is important to understand the habit forming potential of your product. It also helps you to identify areas of improvement.
  • As with all types of testing, this should be done regularly as it is an iterative process.
  1. Identify
    • Who are the product’s habitual users?
    • Define the target user.
    • Use research data to identify this.
  2. Codify
    • Determine the steps those users take when interacting with your product.
    • You’re looking for the habit path, the user journey, the user story.
    • Identify the triggers that “hook” the user.
  3. Modify
    • Based on what you’ve learned from the first 2 steps, update your product to make it more engaging and useful to your audience.

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