Reading Hooks in the Wild
The model works best as an analysis tool, so run a full loop on Instagram. Internal trigger: the fear of missing a moment, or plain boredom. Action: open the app, scroll. Variable reward: an unpredictable feed of tribe (likes, comments on your post) and hunt (what did everyone post?). Investment: post a photo, follow people, and every one of those loads future triggers aimed at both you and others.
Pinterest runs a hunt-heavy loop: the trigger is the itch to find ideas, the endless grid delivers variable discovery, and every pin saved builds a board (stored value) that makes the product more yours. Email may be the oldest hook of all, with all three reward types and decades of stored value in every inbox.
Now run the audit on your own product: what's the internal trigger, is the action tiny, where's the variability, what does the user deposit? Most products that fail to retain are missing a specific step, usually investment. Naming the missing step is the beginning of the fix.
Key idea
Diagnose any product, including yours, by walking the four steps. Retention problems are usually one specific missing step in the loop, most often the investment.