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Growth · Scale-up

Hook Model

The Hook Model, from Nir Eyal's book 'Hooked,' describes how products create habitual usage through a four-phase cycle: Trigger (what prompts the user), Action (the simplest behaviour in anticipation of reward), Variable Reward (the unpredictable payoff that creates craving), and Investment (what the user puts in that makes the product better with use). Products that master the Hook cycle don't need expensive advertising — they become part of users' routines.

When to use this framework

  • You want to increase user engagement and daily active usage
  • Your product is useful but people forget to use it
  • You need to reduce dependence on paid acquisition by building organic habits
  • You're designing onboarding flows and retention loops
  • You want to understand why competitors' products are 'sticky' and yours isn't

Before you start

Have a clear understanding of your core user and their daily routines. The Hook Model works best for products that could be used frequently (daily or near-daily).

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Worked Example

Instagram (2012-2014)

1. Trigger — What brings the user back?

Triggers can be external (notifications, emails, ads) or internal (emotions, routines, situations). The goal is to move from external to internal triggers over time.

What external prompts drive users to open your product? Push notifications, emails, social media mentions, word of mouth, ads, or environmental cues.

1. Push notifications ('X liked your photo,' 'X started following you,' 'X posted for the first time in a while') 2. Notification badges (red dot on app icon) 3. Email digests ('You have unseen notifications') 4. Social triggers — someone mentions seeing your post, asks 'Did you see X's photo?' 5. Environmental: see something photogenic → think 'this would make a great Instagram'

What emotion or internal state drives users to your product without external prompting? Boredom, loneliness, uncertainty, FOMO, anxiety, curiosity? The strongest products attach to negative emotions that users want to resolve.

Boredom (waiting in line, commuting, before bed). FOMO (what are my friends doing?). Loneliness (desire for social connection and validation). Creative expression (captured a beautiful moment, want to share it). Curiosity (what's new in my feed?). The primary internal trigger is a moment of micro-boredom combined with a desire for social connection. Users don't think 'I'll open Instagram' — they just find their thumb tapping the icon automatically.

How strongly associated is your product with the internal trigger? 1 = users never think of you, 10 = you're the automatic response to that emotion.

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2. Action — The simplest behaviour

The action is the simplest thing the user does in anticipation of a reward. It must be easier than thinking. Fogg's model: Behaviour = Motivation + Ability + Trigger.

What is the simplest action the user takes? Scrolling a feed, typing a search, opening the app, pressing a button. The lower the friction, the higher the habit potential.

Open app → scroll feed. That's it. The action is a single thumb swipe. No typing, no searching, no deciding. The feed is immediately there with fresh content. For posting: point camera → tap → add filter → share. Made photography effortless.

What motivates the user to take the action? Pleasure/pain, hope/fear, social acceptance/rejection. The action should require minimal motivation because the trigger is strong.

Curiosity (what's new?), social connection (see friends' lives), and the anticipation of social validation (did my last post get likes?). The motivation is almost unconscious — the internal trigger is so strong that users open the app without thinking about why.

How easy is the action to perform? Rate: 10 = zero effort (swipe, tap), 1 = requires significant time, money, thought, or physical effort.

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3. Variable Reward — The unpredictable payoff

Variability is what creates craving. Predictable rewards satisfy; unpredictable rewards create desire. Three types: tribe (social), hunt (resources/information), and self (mastery/completion).

Social rewards: likes, comments, follows, recognition, acceptance. Do users get social validation from using your product?

Likes, comments, new followers, being mentioned or tagged. The red heart animation when someone likes your photo. Seeing your follower count grow. Comments from friends. DMs. The unpredictability of who will engage with your content and how much engagement you'll get creates a slot-machine effect.

The reward of finding something valuable: news, deals, information, content. The variability of a feed — you never know what you'll find.

The infinite scroll feed — you never know what you'll see next. Beautiful photography, funny memes, celebrity content, friends' stories. The Explore page is pure hunt reward — algorithmically curated content you didn't know you wanted to see. Each scroll reveals something new.

Personal satisfaction: completing a task, levelling up, inbox zero, streaks, achievement. The reward of competence and consistency.

The satisfaction of posting a beautiful photo. Curating an aesthetic grid. Building a 'streak' of posting. The sense of creative expression and identity construction through your profile. The mastery of filters and composition.

How variable (unpredictable) is the reward? 10 = every session is different and surprising, 1 = completely predictable outcome every time.

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4. Investment — Loading the next trigger

Investment is what the user puts into the product that makes it better with use and increases the likelihood of returning. Data, content, followers, reputation, or skill. Investment loads the next trigger.

What do users put into your product that makes it more valuable to them? Data, preferences, content, social connections, reputation, time spent learning. The more invested, the harder to leave.

1. Photos and content (your visual history, memories) 2. Followers and following (social graph — takes months/years to build) 3. Profile curation (aesthetic grid, bio, highlights) 4. Direct message history (conversations) 5. Social capital (reputation, influence, follower count) 6. Learned preferences (algorithm understands what you like)

How does the investment create the next trigger? E.g., adding friends → they post content → you get a notification → you open the app. The investment should naturally create the next external trigger.

When you post a photo → friends see it → they like/comment → you get a push notification → you open the app to see who engaged → you see the feed → you scroll → you see something worth commenting on → that person gets notified → cycle continues. When you follow someone → they post → you get content in your feed → next time you're bored, there's fresh content waiting. Every investment (post, follow, like, comment) generates future triggers for both you and others.

How hard is it to leave once invested? 10 = years of irreplaceable data/connections, 1 = no cost to switch.

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5. Hook Assessment

Average of trigger strength, action ease, reward variability, and switching cost. Higher = stronger habit loop.

Which phase is weakest? That's where your habit loop breaks. Focus your next effort there.

Instagram's hook is remarkably complete. If there's a weak link, it's in the investment → trigger loading for occasional users who don't post frequently. Users who only consume (scroll but never post) have a weaker hook because they're not loading triggers through content creation. Instagram addressed this with Stories (lower-effort posting), Reels (consumption-focused), and increasingly aggressive push notifications for non-posters ('Your friend just posted — check it out').
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