Book notes

Hooked by Nir Eyal

Read in December 2018

"Seventy-nine percent of smartphone owners check their device within fifteen minutes of waking up every morning."

Cognitive psychologists define habits as automatic behaviors triggered by situational cues, things we do with little or no conscious thought.

The Habit Zone

Warren Buffett once said, "You can determine the strength of a business over time by the amount of agony they go through in raising prices." Buffett and Munger understand that habits give companies greater flexibility to increase prices.

Viral Cycle Time is the amount of time it takes a user to invite another user, and it can have a massive impact.

Many entrepreneurs fall into the trap of building products that are only marginally better than existing solutions, hoping their innovation will be good enough to woo customers away from existing products. When it comes to shaking consumers’ old habits, these naive entrepreneurs often find that better products don’t always win—especially if a large number of users have already adopted a competing product.


External triggers

  • Paid (advertising)
  • Earned (virality)
  • Relationship (friend advice)
  • Owned (app icon on home screen)

Yet external triggers are only the first step. The ultimate goal of all external triggers is to propel users into and through the Hook Model so that, after successive cycles, they do not need further prompting from external triggers. When users form habits, they are cued by a different kind of trigger: internal ones.

Internal triggers

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

Emotions, particularly negative ones, are powerful internal triggers and greatly influence our daily routines.

Feelings of boredom, loneliness, frustration, confusion, and indecisiveness often instigate a slight pain or irritation and prompt an almost instantaneous and often mindless action to quell the negative sensation.


The trigger, driven by internal or external cues, informs the user of what to do next; however, if the user does not take action, the trigger is useless. To initiate action, doing must be easier than thinking.

Dr. B. J. Fogg, Director of the Persuasive Technology Lab of Stanford University has a behavior model for actions.


User must have sufficient motivation. Fogg states that all humans are motivated to seek pleasure and avoid pain; to seek hope and avoid fear; and finally, to seek social acceptance and avoid rejection.


User must have the ability to complete the action. Simplifying the steps for taking an action is important.


A trigger must be present to activate the behavior.

Variable Reward

  • Making reward variable increases the craving.
  • Skinner’s Box

Rewards of the Tribe

The search for social rewards fueled by connectedness with other people.

  • Checking out facebook and liking your friends’ photos
  • Answering questions on stackoverflow for contributing the community

Rewards of the Hunt

The search for material resources and information.

  • Machine gambling (especially slot machines)
  • Checking Twitter feed and hunting for the information
  • Infinite scrolling on Pinterest

Rewards of the Self

The search for intrinsic rewards of mastery, competence, and completion.

  • Playing video games, levelling up, earning items, slaying unslayable bosses
  • Checking e-mail to feel important and look for new things


  • More users invest time and effort into a product or service, the more they value it.
  • Documents, bookmarks, followers, likes, tinder matches, spotify playlists, lastfm listen counts...
  • IKEA example: you build the furniture yourself and you value it more.

What are you going to do with this?

The Manipulation Matrix

Build the change they want to see in the world. — Mahatma Gandhi


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