What it is
The decoy effect (also called the attraction effect or asymmetric dominance) happens when adding a third option that is clearly worse than one alternative, but not the other, increases the share of people choosing the option it’s worse than (Huber, Payne and Puto, 1982).
Example: a cinema sells popcorn small for €4 and large for €7. Add a medium for €6.50 and more people may buy the large, because next to the medium it looks like a bargain.
How strong is the evidence?
Mixed. The original studies found the effect in controlled choices between options described with numbers. A later series of studies found it was often absent when options were presented more realistically, for example as pictures or with attributes people experience rather than read (Frederick, Lee and Baskin, 2014).
So the effect is real in some conditions and fragile in others. Pricing tables, which present numbers side by side, are closer to the conditions where it appears, but there’s no guarantee for your page.
How it works on a page
People find absolute value hard to judge, so they compare options. A dominated option makes one comparison very easy (“the large is clearly better than the medium”), and easy comparisons feel like good reasons.
Examples
Ecommerce
- Honest: three real pack sizes where the larger packs are genuinely cheaper per unit, shown with the per-unit price.
- Manipulative: a size that’s never stocked, or priced only to make another look good.
SaaS
- Honest: three plans built for three real customer types, with clear differences.
- Manipulative: a middle plan with almost no features at nearly the top price, created only to push upgrades.
Ethics
Comparison is fine; manufactured comparison isn’t. Options that exist only to mislead people about value belong with other manipulative designs (Deceptive.design). Every plan or size you show should be one you’d be happy to sell.
How to test it
- Hypothesis: “Because pricing-page recordings show visitors comparing the two plans back and forth, we believe adding a per-seat price to each plan will increase upgrades to the team plan, because the comparison becomes easier.”
- Primary metric: revenue per visitor (or paid sign-ups), not clicks on a plan.
- Guardrails: refunds, downgrades in the first 30 days, support tickets about plans.
- Watch the mix: a decoy can move people between plans without increasing total revenue.
Related: anchoring and choice overload.