Technique · Hooked
Shorten the viral cycle through daily use
Put social actions inside the daily loop (tag, mention, share a result, collaborate) so frequent users invite others sooner, make use visible and joinable where people gather, and measure the days from sign-up to first invite and from invite to acceptance.
Plain label: faster invite loopsAlso known as: viral cycle time, K-factor, invite loop, word of mouth, in-room sharing, host mode, community leader
How it works
The time it takes one user to bring in another sets how fast growth compounds. Daily users start more invite loops and more people are around to answer them, so frequent use shortens the cycle. In the book's model, over 20 days a 2-day cycle yields about 20,470 users and a 1-day cycle over 20 million.
Evidence warning
One sentence in the book states the direction backwards; its argument is that daily use shortens the cycle. The growth figures are the book's illustration, not data.
Before you start
- At least one segment already has product-market fit.
How to build it
- B2B
- Mentions and assignments that bring a colleague into a document they need to act on.
- Mobile
- Room codes or QR links so people in the same class, gym or meeting can join in one step.
- Web
- Shared links that open straight to the item, not a sign-up wall.
What can go wrong
- Contact scraping or auto-posting.
- Invites that bring in people who never activate.
Pairs well with
- Invites that carry value to the person invited.
- Ask for shares right after a win.
In practice
Where it shows up
Limits
What we don’t claim
- The Hook Model is a practical design tool, not a validated or complete theory of behavior.Hooked, Introduction
- Left Brain and Right Brain are a metaphor for extrinsic and intrinsic motivation, not a claim about neuroscience.Actionable Gamification Ch.13, pp.342-343
Sources
Hooked · Nir Eyal
Ch.1 · Ch.7
Source IDs: HK-MON04HK-MON09HK-MON10
Book content is paraphrased, never quoted at length. Last verified October 24, 2026.
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