Book Review: Hooked – How to Build Habit-Forming Products

Book Review: Hooked – How to Build Habit-Forming Products

What makes you check your phone 100 times per day? Why do you always use Google instead of Bing? Or why do lay awake at night, scrolling through your Instagram/FB/LinkedIn feed, even when you know you should be sleeping?

In Hooked: How to Build Habit Building Products, Nir Eyal provides the exact model that many digital products use to make us want to use it. According to the author, all these apps use the Hook model — finding ways to intertwine their usage into our daily lives, routines, and habits.

The Hook Model:

In summary, the book Hooked provides a model to ‘hook’ users. It is a model to make them come repeatedly. The book explains the process in Four Steps: Trigger, Action, Variable Reward, and Investment.

The Hook – Process Steps

While reading book I realized that this book itself is the best example of Hooked Model…

Trigger – Book recommendation from one of my connections. So got external trigger.

Action – checked reviews of the same and decided to read. Book purchased.

Reward – the reward, which I expected, is to have good insights from the book as well satisfaction of completing the reading of the good book

Investment – Time and efforts invested in reading and acquiring thoughts of the Author. Also in putting thoughts through this post. Also while recommending this book to others, I will be also reading the same for a couple of times more to get the thoughts to imbibe in me.

AND this may ACT as TRIGGER to next reader

This is a simple example of the hooked model. In the book, the author expands on each different section.

The Hook Model starts with the trigger. In this example, the trigger was a notification on your phone. According to Eyal, the trigger can be both internal and external. In this case, the Instagram notification is an external trigger. Similarly, an advertisement, email, or even word-of-mouth marketing may be the external trigger you need as a user to start engaging with a product. Alternatively, a trigger can be internal. This is the case when users have already gone through the Hooked model (and the circle in the image above) once or several times. You yourself trigger a need or want to open the Instagram app, without any external interference.


What is the action you want a user to take in/with your product? The goal of the product team is to (among many other things) make the action as easy as possible. In both this model and life in general, an action consists of three aspects: motivation, ability, and trigger. This is also called the Fogg Behavioral Model, represented as B = MAT.

Take a simple example: the behavior (or action) of doing online buying of clothes. If you do so you need to be 1) motivated to do so, 2) able to do so, and 3) you need a certain trigger. Therefore, if you do not feel like doing online shopping (motivation), if a website is not working (ability) or if due to lockdown you do not need new clothes to wear (trigger), you are not very likely to do online shopping.

Variable Reward:

Interestingly, the reward a user gets from a product should not be the same every time. Just like with gambling, there should be a variable reward — sometimes you get X, sometimes you get Y, or perhaps sometimes you get nothing at all. Preferably, a product has so-called “infinite variability”. You can find this infinite variability in the un-ending scroll of products like Instagram, Amazon, LinkedIn, Facebook, Pinterest, or even certain news sites. You never know what you can expect, making the product new and exciting, every time you open it.


Users making an investment in your product helps them get back to the product in several ways. First, investing in the product usually improves the product itself. In this sense, a user’s investment in your product will make it more likely for him/her to stick with your product, even if there are better alternatives on the market.

Applying the Hooked Model:

Whenever you read a business book, it is important to look at how to apply it to your specific case. In this book, the Author provides several questions and small to-do at the end of every chapter that you can use to apply the Hooked model to your product.

Specifically, you could look at your product (or service) and answer questions such as:

  • Which internal trigger does your user experience most frequently?
  • Which resources are limiting your users’ ability to accomplish the tasks [or actions] that will become habits?
  • What are 3 ways your product might increase users’ search for variable rewards?
  • What ‘bit of work’ [or investment] are your users doing to increase their likelihood of returning?

These are just a few questions from the book; if you truly want to apply this model to your product, I recommend reading all of them.

So get hooked…..

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