Biases › Principle
Principle
Incentive (principle)
A reward for doing something changes what we do.
Not a bias: a reward for doing something, such as a referral reward or sign-up discount.
Ryu & Feick (2007), A penny for your thoughts: referral reward programs and referral likelihood.
What is Incentive?
Incentive is a behavioural design principle (principle family): not a bias: a reward for doing something, such as a referral reward or sign-up discount. Incentives change behaviour by paying for it. Nudgeswipe rates the evidence as strong. Source: Ryu & Feick (2007), A penny for your thoughts: referral reward programs and referral likelihood.
The research
Incentives change behaviour by paying for it. Referral rewards and sign-up or win-back discounts are incentives, because you only get them if you act. Reciprocity applies alongside only when one side receives a genuine, unconditional gift (for example, the friend in a give/get scheme). Referral-reward research finds that the size and split of the reward matter, especially between strong and weak ties.
● Strong evidence
Source: doi.org/10.1509/jmkg.71.1.084
Key takeaways
- Honest nudge
Make the reward, who gets it and the conditions clear.
Example: Gymshark rotates five offers in one top banner → - Dark-pattern line
Rewards with hidden conditions, or 'limited time' with no end date. deceptive.design →
Grey-area example: NordVPN shows "Save 69%" on a 2-year plan, with the renewal price in small print →
Use it
Apply this with your agent
The prompt carries this bias, its evidence rating and the honest-vs-dark line.
ChatGPT, Claude, Grok and Cursor open with the prompt filled in (it is also copied, in case the prefill doesn't load). Gemini and Codex don't support prefilled links, so the prompt is copied and the app opens; paste it in.
Frequently asked questions
What is Incentive?
Incentive is a behavioural design principle: not a bias: a reward for doing something, such as a referral reward or sign-up discount.
How does Incentive work?
Incentives change behaviour by paying for it. Referral rewards and sign-up or win-back discounts are incentives, because you only get them if you act. Reciprocity applies alongside only when one side receives a genuine, unconditional gift (for example, the friend in a give/get scheme). Referral-reward research finds that the size and split of the reward matter, especially between strong and weak ties.
How strong is the evidence for Incentive?
Nudgeswipe rates it strong evidence. Original source: Ryu & Feick (2007), A penny for your thoughts: referral reward programs and referral likelihood.
How can you use Incentive honestly?
Make the reward, who gets it and the conditions clear.
When does Incentive become a dark pattern?
Rewards with hidden conditions, or 'limited time' with no end date.
Which brands use Incentive?
Nudgeswipe has 19 teardowns of brands using it, including Gymshark, Ocado, NordVPN, Squarespace, Babbel. Whether it lifted their results is not public unless a teardown cites it.
In the wild
19 real examples
Gymshark rotates five offers in one top banner
Gymshark · Homepage banner · £ as captured
Ocado uses Tesco's prices as its reference
Ocado · Homepage · £ as captured
NordVPN shows "Save 69%" on a 2-year plan, with the renewal price in small print
NordVPN · Pricing page · $ as captured
Squarespace stacks an undated 20% code on top of a free trial
Squarespace · Pricing page
Babbel runs a live countdown on a 20% "Lifetime" code
Babbel · Homepage banner
Audible offers Prime members $0.99 a month for 4 months, plus a $20 credit
Audible · Homepage banner · $ as captured
Perplexity stacks "LIMITED TIME" bonus credits on top of annual-billed prices
Perplexity · Pricing page · $ as captured
Lovable frames the yearly plan as "2 months free" and starts with "No credit card needed"
Lovable · Pricing page · $ as captured
The Times sells a puzzles-only side door: "£1 for your first 3 months"
The Times · Subscribe page · £ as captured
MoneySuperMarket attaches "Earn £15" to a quote and promises to price-match and more
MoneySuperMarket · Homepage · £ as captured
Compare the Market leads with "Save up to £566" and footnotes that 51% could achieve it
Compare the Market · Homepage · £ as captured
Three leads with "Save up to £1035" on trade-in and dates its price rises
Three · Homepage · £ as captured
Moonpig pairs a "FREE CARD with any bouquet" with 30% off the first card
Moonpig · Homepage
Replit shows "$20 $18 / month, billed annually" and bundles model credit into the price
Replit · Pricing page · $ as captured
v0 gives "$2 of free daily credits on login" and a one-time $5 for new users
v0 (Vercel) · Pricing page · $ as captured
Share the Love ♥️ Give $20 / Get $20
Tea Forté makes referral a two-way gift, and offers a snooze
Tea Forté · Email · $ as captured
Get $20 for each friend you refer (and your friend gets $100 off)
Nanit gives the friend five times what the referrer gets
Nanit · Email · $ as captured
It's been a while.
Uniqlo's win-back gives a $10 voucher with a $100 threshold
Uniqlo · Email · $ as captured
Earn $100* when you refer a friend
Castlery frames referral as "a new beginning for them, a little thank-you for you"
Castlery · Email · $ as captured
5 new nudges, every Friday
Five real product and marketing moments, the psychology behind each, and one thing to try. Weekly issues start soon. Your email is stored with our email provider (Resend) and used only for this newsletter.