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description: Design habit-forming product experiences using the four-phase Hook cycle
---

# Hook Model (Nir Eyal)

Build habitual engagement through a four-phase loop: Trigger, Action, Variable Reward, and Investment.

## Steps

1. **Trigger** -- Identify external triggers (notifications, emails) and the internal trigger (emotion/need) you want to own
2. **Action** -- Define the simplest behavior the user takes in anticipation of reward (Fogg: motivation + ability + trigger)
3. **Variable Reward** -- Design rewards with variability: tribe (social), hunt (resources), or self (mastery)
4. **Investment** -- Identify what the user puts in (data, content, reputation) that improves the next loop
5. Map how the investment creates or loads the next trigger

## Output Format

| Phase | Design |
|-------|--------|
| Internal Trigger | [Emotion or need] |
| External Trigger | [Channel and message] |
| Action | [Simplest user behavior] |
| Variable Reward | [Type: tribe/hunt/self + description] |
| Investment | [What user stores/creates] |

**Loop reinforcement:** [How investment loads next trigger]