How do companies create habit forming products? It’s simple: They manufacture them.

In 2008 Nir Eyal was part of a team of Stanford MBAs starting a company backed by “some of the brightest investors in Silicon Valley.”

They wanted to build a platform to place ads into online social games. Eyal wondered how mind manipulation worked — how do products change our actions, and create compulsions.

How do you engineer user behaviour? Are there moral implications? Could these forces be used for good (nudging).

So he looked around for a guide. He couldn’t find anything that satisfied him so he documented his experiences, reading, and observations of hundreds of companies “to uncover patterns in user experience designs and functionality.” He wanted to know what was common between the “winners” and determine what was missing from the “losers.”

The result of this effort is his book Hooked: How to Build Habit-Forming Products and the creation of the Hook Model: a four-phase process that companies use to form habits.


the hook model Farnam Street

That sounds like a growth hacker’s dream.

Let’s take a look.

1. Trigger

A trigger is the actuator of behavior — the spark plug in the engine. Triggers come in two types: external and internal. Habit-forming products start by alerting users with external triggers like an email, a website link, or the app icon on a phone.For example, suppose Barbra, a young woman in Pennsylvania, happens to see a photo in her Facebook newsfeed taken by a family member from a rural part of the state. It’s a lovely picture and since she is planning a trip there with her brother Johnny, the external trigger’s call-to-action intrigues her and she clicks.

By cycling through successive hooks, users begin to form associations with internal triggers, which attach to existing behaviors and emotions.When users start to automatically cue their next behavior, the new habit becomes part of their everyday routine. Over time, Barbra associates Facebook with her need for social connection.

2. Action

Following the trigger comes the action: the behavior done in anticipation of a reward. The simple action of clicking on the interesting picture in her newsfeed takes Barbra to a website called Pinterest, a “pinboard-style photo-sharing” site.

This phase of the hook, as described in chapter three, draws upon the art and science of usability design to reveal how products drive specific user actions. Companies leverage two basic pulleys of human behavior to increase the likelihood of an action occurring: the ease of performing an action and the psychological motivation to do it.


3. Variable Reward




4. Investment

The last phase of the Hook Model is where the user does a bit of work. The investment phase increases the odds that the user will make another pass through the hook cycle in the future. The investment occurs when the user puts something into the product or service such as time, data, effort, social capital, or money.

