Hooked by Nir Eyal: A Framework for Creating Habit-Forming Products

Jade Shyu
Jade Shyu
Nov 13, 2017 · 4 min read

Ever since SXSW 2017, I’ve been eager to learn more about behavioral science. Hooked: How to Build Habit-Forming Products by Nir Eyal is my first foray into the psychology behind addictive digital products.

I recommend this book for:

  • Junior product designers
  • Product managers
  • Anyone aiming to build the next social or entertainment app
  • Anyone who is new to tech and would like to learn more

In Hooked, Eyal introduces the Hook Model and analyzes today’s most popular apps under this framework. Below, I share my favorite morsels from the book, with the hope that it sparks your interest and imagination.

The Hook Model

1. Trigger

A trigger is an external call to action or an internal need that “cues the user to take action”. An example of an external trigger is an email, while an internal trigger could include emotions, such as fear (of missing out). It’s the reason you started to do something.

2. Action

The action is “the simplest behavior in anticipation of reward”. According to Behavior Scientist BJ Fogg, in order for an action to take place, the user must have 1) sufficient motivation, 2) ability to complete the action, and 3) a trigger to activate the behavior (represented as B = MAT). The more effort, physical or mental, the less likely the action will take place. BJ Fogg also asserts that a task’s difficulty is influenced by six “elements of simplicity”, which include time, money, physical effort, brain cycles (mental effort), social deviance (how accepted a behavior is), and non-routine (how much it matches or disrupts current routines).

3. Reward

During the reward phase, a user’s needs are satisfied. In the 1950s, psychologist B.F. Skinner conducted experiments focusing on variable rewards. He discovered that introducing randomness to a bird food dispenser increased the frequency of a pigeon tapping on the dispenser. This principle of variable rewards can be applied to these 3 types of rewards:

  • Rewards of the Tribe: social rewards driven by our connectedness with other people. These make us feel “accepted, attractive, important, and included”. Examples include Stack Overflow and Facebook.
  • Rewards of the Hunt: the pursuit of resources and information. Examples include machine gambling and Twitter.
  • Rewards of the Self: the search for “intrinsic rewards of mastery, competence, and completion”. Examples include Codecademy and video games.

Why does this matter? In the late 2000s, two Q&A websites came to prominence, Mahalo and Quora. Mahalo offered a virtual currency as incentive, while Quora offered social rewards and recognition. In the end, Quora succeeded because it was able to define what matters to users.

4. Investment

Spending time or effort on a product or service causes someone to value it more.

  • Hence, the likelihood of the person using it again increases. Examples of this include building an iTunes library, adding followers/content on a social networking site, or building a reputation on a commerce site.
  • However, spending more time to learn software also means a person is less likely to switch to a competing product.
  • As a person invests more time into a product, that allows the next trigger to be loaded. This brings the person back into the product. Examples of this include Tinder (match > message) and Snapchat (self-destruct messages means a timely reply).

Types of Biases

  1. The Scarcity Effect: The appearance of scarcity affects perception of value. This is illustrated by the cookie jar study comparing the value of two jars of cookies, one with only two cookies and one with 10 cookies.
  2. The Framing Effect: Our surroundings shape perception, which can lead to erroneous judgments. This is illustrated by a wine study, where researchers informed wine tasters the cost of wines. As wine price increased, wine tasters enjoyed the wine more, but they were tasting the same wines.
  3. The Anchoring Effect: “People often anchor to one piece of information when making a decision.” As an example, this happens when stores offer sales, and there’s a product that costs less at normal price.
  4. The Endowed Progress Effect: People get a motivation boost as they believe they’re reaching a goal. We can see this on LinkedIn’s profile completion progress bar.

Additional Notes

Eyal takes a chapter to ask readers to “assess the morality” behind manipulating users. He then highlights the Bible App as a product that uses the Hook model in a positive way. Not only does the app provide triggers on a timely basis, but it also offers bite-sized readings randomly and allows people to invest effort by storing and annotating meaningful verses.

As a way to improve products, Eyal asks readers to use “Habit Testing”, a process inspired by the Lean Startup movement. The steps are to 1) identify the product’s habitual users, 2) define the actions taken by the most loyal users, and 3) make changes to improve the product.


  • The analogies and examples clearly illustrate the conceptual ideas.
  • There’s a “Do This Now” section that functions as a workbook, with questions and ideas for readers to work on.
  • It helped me discover relevant studies and concepts.


  • Many examples deal with “vitamins” in the social or entertainment space, which are “nice to haves” targeted to the consumer. This is different from “painkillers”, such as utility or enterprise products that solve a specific problem. If Eyal were to write another book, I’d like to see an exploration of other user cases.
  • Anyone who is familiar with the companies mentioned in the book may find it redundant.

Related resources

Jade Shyu

Written by

Jade Shyu

UI / UX Designer. Curious Learner. http://jadeshyu.com

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