behavioral ux
Back to library

Default effect

The default effect is the tendency to accept the pre-set option instead of actively choosing another, because changing it takes effort and feels like a decision.

Choose your plan
Billed yearly · cancel anytime
  • StarterFor one person.
  • PlusFor small teams.
  • ProFor growing businesses.
Select a plan to continue
Without a default
Choose your plan
Billed yearly · cancel anytime
  • StarterFor one person.
  • PlusRecommendedFor small teams.
  • ProFor growing businesses.
Change your plan at any time
With a default
Live demo

Defaults work through three channels: switching takes effort, the preselected option reads as a recommendation, and once it is in place, giving it up feels like a loss. The effects can be large. In an online experiment, 82% of participants agreed to be organ donors when donating was the default, compared with 42% when it was not (Johnson & Goldstein, 2003). When a German energy supplier preselected its green tariff for almost 42,000 households, about 70% kept it, while only about 7% chose it when they had to opt in, a nearly tenfold difference that follow-up experiments suggest was not simply people overlooking the default. A meta-analysis of 58 studies found an average effect of d = 0.68, stronger for consumer decisions and when the default reads as a recommendation, with wide variation between studies (Jachimowicz et al., 2019). Defaults can also backfire. Across 13 million New York taxi rides, higher preset tip suggestions raised tips but also led more riders to leave no card tip at all.

How to apply

  • Preselect the option that is right for most users, such as the plan most customers end up on, and label it “Recommended” so the endorsement is explicit.
  • Show the default where the choice happens, as a preselected option with the alternatives visible and one click away, not buried in settings.
  • Fill in what you already know (country, currency, the user's last choice) so the default saves effort instead of steering.
  • Default to the option that serves the user's own long-term goal, such as privacy-friendly settings or saving progress automatically.
  • Test preset amounts for tips, donations and quantities. Higher suggestions raise amounts but can push people out of the choice entirely.

What to avoid

  • Pre-ticked boxes that add cost, like insurance, donations or add-ons. In the EU, extra payments need express consent, and a pre-ticked box does not count (Consumer Rights Directive, Art. 22).
  • Pre-ticked consent for marketing emails or cookies. Under GDPR, a pre-checked box is not valid consent (CJEU, Planet49, 2019).
  • Defaults that obviously serve the business. Shoppers read defaults as signals of the seller's intentions and judge them accordingly.
  • Preset amounts set so high that people reject the whole thing, as with the taxi riders who skipped the card tip.
  • Relying on inertia to keep people in subscriptions or settings they would not choose actively.

Real-world examples

Instacart+ plan screen with the $99 annual plan selected and badged best value above an unselected $9.99 monthly plan, under a keep annual plan button.
Instacart preselects the annual plan, marks it “Best value”, and labels the primary button “Keep annual plan”, so the cheaper-per-month option is the one that needs no decision.
Lyft set a default tip screen with the default tip toggle on and 10 per cent selected among 15, 20 and 25 per cent options.
Lyft makes the tip a standing default rather than a per-ride question: 10% is set once in settings and applied to every ride unless the rider changes it.
UNIQLO checkout shipping step with standard $7.99 selected over priority and express, and an unticked require signature upon delivery $4.00 checkbox.
UNIQLO preselects the cheapest shipping speed and leaves the paid signature-on-delivery box unticked, so the only default that adds cost is one the shopper has to tick themselves.
Postmates add a tip screen with 18 per cent at $7.26 selected among 15, 20 and 25 per cent presets and an edit option.
Postmates preselects 18% in the tip row and prints what each percentage costs, the preset-tip pattern that the taxi research found raises tips and raises refusals at the same time.
1 / 4

References

For agents

An agent-friendly guide to this principle lives at /agents/default-effect.md.

Our MCP server and skills for all principles are coming soon.

Similar principles

Disclaimer: The theories here are just that — theories. They may not apply universally and should be considered in context. Use your own judgment and consult additional sources when applying these principles.