The Hook Model: A Habit-Forming System

Overview of the Hook Model

The hook model is a habit-forming system that consists of four components: trigger, action, variable reward, and investment. This model was first described by Nir Eyal in his book, Hooked: How to Build Habit-Forming Products.

Trigger

A trigger is a prompt that comes from the environment or internally, such as emotions or thoughts. External triggers can be notifications, ads, or recommendations from friends. Internal triggers are negative emotions, such as anxiety, fear, or boredom.


// Example of an external trigger
function sendNotification(user) {
// Send a notification to the user
console.log(`Notification sent to ${user}`);
}


Action

The action is the behavior a user goes through in anticipation of the reward. The action should be easy to complete and have minimal friction.



Like

Variable Reward

An unpredictable reward that satisfies the user’s needs and encourages them to re-engage with the product. There are three types of variable rewards:

• Rewards of the tribe: social validation, such as likes or comments on social media.
• Rewards of the hunt: tangible rewards, such as money or prizes.
• Rewards of the self: feelings of fulfillment or accomplishment.


# Example of a variable reward
import random

def give_reward(user):
# Give a random reward to the user
reward_type = random.choice(['tribe', 'hunt', 'self'])
if reward_type == 'tribe':
# Give social validation (e.g. likes, comments)
elif reward_type == 'hunt':
# Give tangible reward (e.g. money, prize)
else:
# Give feeling of fulfillment or accomplishment


Investment

An action that users take to improve future rewards’ quality. Investments can be content curation, data, reputation, or social connections.


// Example of an investment
function curateContent(user) {
// Curate content for the user (e.g. show recommended articles)
console.log(`Content curated for ${user}`);
}


Key Takeaways

1. To build a habit, you need a trigger, action, variable reward, and investment.
2. True habits are based on internal triggers, but products must first rely on external triggers.
3. Investments improve the quality of rewards over time and make leaving the product harder.
4. The hook model is just a tool, and its ethics depend on how it’s used.
5. Make sure the habits your product strives to build enhance users’ lives, not harm them.

Learn more about the hook model