EffectValuation & choice · Framing Effect · Entry 220
Decoy Effect – when an inferior option changes the comparison between better options
Decoy Effect is a context effect in which adding an inferior option can increase the choice share of another option. In the classic attraction-effect setup, the decoy is clearly worse than the target on important attributes, which can make the target easier to justify against a competitor.
Where can it show up?
- Pricing tables: a third plan can make one of the original plans look better by comparison.
- Product choice: an inferior model can change how price and quality trade-offs are evaluated between two stronger alternatives.
- Recommendations: adding or removing an option can change the relative appeal of the options that remain, even when their own features do not change.
A better check
- Compare the main options before and after the extra option is added.
- Ask whether the extra option is dominated by one alternative but not by the other.
- Remove the suspected decoy and see whether your preference between the remaining options changes.
- Compare the options on the attributes that matter to your goal, not only on the contrast created by the menu.
- Do not assume that every three-tier price table creates a decoy effect. The effect is well documented, but its size and even its direction depend on the choice set and context.
Evidence review
well documented, context-dependentWhat the evidence supports
The decoy effect is a well-documented family of context effects in which adding an inferior or otherwise strategically positioned alternative can change choice shares among the original options. The classic attraction effect uses an asymmetrically dominated decoy that is worse than the target but not necessarily worse than the competitor. The effect is not guaranteed: its size depends on the geometry of the options, prior preferences, task design and other moderators, and preregistered replications have found both successful and weak or null results.
How researchers describe the pattern
Research offers several explanations, including contrast between attribute trade-offs, changes in relative value, ease of justification and attention to particular dimensions. A 2024 integrative review concludes that there is still no clear consensus on one underlying mechanism and separates attraction, compromise and phantom-decoy effects rather than treating every extra option as the same phenomenon.
Practical interpretation
When a third option seems to make one plan suddenly look obvious, compare the original alternatives without it and score the options on the attributes that matter to the decision. Check whether the suspected decoy is actually dominated by the target and whether removing it changes the preference between the remaining options. For product or pricing design, test the full choice set rather than assuming that a three-tier menu will reliably create the effect.
Reviewed sources
- Choice in Context: Tradeoff Contrast and Extremeness Aversion foundational experiments · 1992 · DOI 10.1177/002224379202900301
- The asymmetric dominance effect: Reexamination and extension in risky choice – An experimental study experimental replication and extension · 2019 · DOI 10.1016/j.joep.2019.05.007
- Revisiting the decoy effect: replication and extension of Ariely and Wallsten (1995) and Connolly, Reb, and Kausel (2013) preregistered replication · 2021 · DOI 10.1080/23743603.2021.1878340
- An integrative review of the decoy effect on choice behavior systematic integrative review · 2024 · DOI 10.1002/mar.22076
Editorial review: 2026-08-18. Evidence status describes this entry, not every study ever published on the topic.
