The principle. Johnson & Goldstein's landmark 2003 paper: countries with opt-out organ donation (you're a donor unless you check a box) have ~99% participation. Opt-in countries (you're not a donor unless you check a box) sit at 4-27%. Same humans. Same form. The default did the work.
Why it works. Defaults exploit three things:
- Effort cost — changing the default takes a tiny amount of energy people don't want to spend.
- Implicit endorsement — "they pre-selected this, so it must be the safe / recommended choice."
- Loss aversion — once a default feels "yours," changing away from it feels like a loss.
Selling applications.
- Pricing tiers. Pre-highlight the tier you want sold. "Most teams your size start on Pro" with a visual badge does heavy lifting.
- Contract length. Default to annual. "Standard agreement is 12 months — happy to walk through monthly if helpful." Watch how rarely they push back.
- Onboarding. Default to white-glove ("we include a 30-day implementation lead — let me know if you'd rather DIY") rather than offering it as an upsell.
- Renewals. Auto-renew with a 30-day notice. The opt-out friction quietly compounds retention.
The honest version. Defaults are powerful enough to be unethical if the pre-selection is bad for the customer. The test: would you defend the default in a customer success review? If yes, ship it. If no, you're abusing a cognitive shortcut.