Hooked: Book Summary & Review

hooked book

Hooked studies “addictive products” and explains what entrepreneurs and marketers can do to make their own products addictive.

Bullet Summary

  • Get other users to provide the first triggers for you: you get free ads and network effect
  • Make the first action to engage with your product as simple and quick as possible
  • To make addictive products give variable rewards

Full Summary

About the Author: Nir Eyal earned an MBA at Stanford University and founded an advertising business with some of his fellow students placing advertisements on Facebook. Eyal grew interested in psychology and behavioral engineering, and “Hooked” is the result of his research.

How Habits Form

Habits form through repetition, and the more you do them, the more automated they become.

Indeed repeated action forms pathways in our brains. And those pathways will stay there even when we manage to stop a habit.

That’s why, sadly, most alcoholics will start drinking again within one year of finishing a detox program.

The Most Successful Products Form Habits

Products that become habits in their users have a marked advantage over the competition.

Users use them more often and stick for the long term. Sometimes forever.
Even if it’s not always good for the users, the habit-forming products will keep exercising a strong pull over the users that will make it hard for the user to ditch.

Habit-forming products also have high entry barriers.
For a new product to take its users, it must be much better.
And sometimes even when they are markedly better it’s still not enough.

Take the QWERTY keyboard, for example. It is by far not the best, but no other keyboard layout can usurp QWERTY’s stronghold among its users because that would mean getting used to a new layout, and it’s not going to happen any time soon.

The Hook Stages

Nir Eyal says that for a product to hook its users, it needs to go through four stages:

  1. Trigger: the event that makes us try the product (initially it’s external, then it becomes external)
  2. Action: what do we need to do to use the product
  3. Reward: deliver pleasure
  4. Investment: what we give in exchange for pleasure (ie.: money, time, information)

1. Triggers

The trigger initially is external because we don’t know about the product.

But over time the pleasure of the reward builds internal mental triggers.

The most frequent internal triggers are emotions, and most often negative ones. Such as boredom, loneliness, confusion, or fear.

However, the reward is often able to give a positive jolt (often a dopamine hit).

Once we get that dopamine a few times we form pleasure links between a certain action and a reward we get.
Over time we will automatically repeat the cycle over and over by ourselves.
When that happens, we’re hooked.

The more popular and catchy a product becomes, the more the trigger can be started by other users. Social networks, for example, add people thanks to the invitation from already existing users.
Free advertisement.

2. Action

To take action an individual must be sufficiently motivated and able to take action.

To be effective a trigger must offer a simple choice of action. The simpler the action to perform, the lower the entry barrier, and the more people will perform the needed action.

3. Rewards

What makes people really hooked is the itch for the reward. The itch is more important than the reward itself.

And the best way to hook people and keep that itch strong is with unpredictable rewards.

A reward which is always present, and always the same, grows us bored.
It’s the anticipation and excitement of unpredictable rewards that hooks us.

Think of Facebook for example. You check it looking if there is a red notification of a like or a message. But it’s not always there, and that’s one of the key variables that keep us going back for more.
It’s similar to when we scroll our feed. Lots of time is just boring stuff. But sometimes we’ll find something awesome that makes us laugh, excites, or even bother us or saddens us.

4. Investment

When we invest in something we feel it’s more valuable.

And investment also works to justify in our mind that what we invest in must be worth it.
So if we’ve done something many times we tell ourselves that it must be valuable.

Two Questions for Ethical Concerns

Producing and working on products that get people hooked can raise some ethical questions.
Nir Eyal proposes two questions to test if your habit-forming concept is ethical or not:

  1. Does your product enhance people’s lives?
  2. Would you use the product yourself?

hooked book

Real-Life Applications

  • If You Wanna Get Stuff Done: Don’t Get Hooked

If you’re a high achiever who wants to be productive and get things done, you must control your hooking machine.
Get un-hooked at unproductive stuff and get hooked on what drives you towards your goals.


  • I wasn’t convinced about the investment stage

I wasn’t convinced by the fourth stage of forming habits. So people get hooked to, say, Facebook because they “invest” scrolling on their feed?
It doesn’t seem to make much sense to me.

I think that if you prod people for answers, they are quite honest that scrolling on their Facebook feed is pretty much useless.
It’s just that they can’t help it.


Good Overview of How Apps & Social Networks Work
Hooked is a good book to understand how some apps and most social media hook people in.

Short and To The Point
Little time and space waste. I appreciate that.


I found “Hooked” to be OK.

It’s good, but I personally didn’t find much new wisdom.

However, it might be different for you.
Especially if you haven’t read much on psychology yet, or if you are interested in habit-forming technologies for entrepreneurial ventures, then this might be a good read for you.

Read the best psychology books or get the book on Amazon

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