Last month I was choosing between two streaming plan tiers: ₩8,900/month (standard) or ₩14,900/month (premium). I was leaning toward standard. Then I noticed a third option: ₩13,500/month with slightly fewer features than premium. Suddenly, premium looked like a steal.
That third option existed for one reason only — to make me choose premium. It worked. I’m a science teacher with five years in the classroom and a personal obsession with cognitive biases, and it still worked on me.
What Is the Decoy Effect?
The decoy effect (also called the asymmetric dominance effect) occurs when adding an inferior third option to a choice set changes people’s preferences between the original two options. The third option — the decoy — is not meant to be chosen. It’s designed to make one of the original options look superior by comparison.
Related: mental models guide
This was first rigorously documented by Joel Huber and colleagues in their 1982 paper “Adding Asymmetrically Dominated Alternatives: Violations of Regularity and the Similarity Hypothesis” in the Journal of Consumer Research.[1] Their findings contradicted classical economic theory, which predicted that adding options should never increase the relative preference for an existing option.
I believe this deserves more attention than it gets.
Classic Demonstration: The Beer Study
Huber’s original experiments used products ranging from cars to beer. When subjects chose between a cheap low-quality beer and a moderately priced medium-quality beer, the split was roughly 50/50. Introduce a decoy — an expensive beer of only marginally higher quality than the medium option — and preferences shifted dramatically toward the medium beer. The decoy reframed the medium beer as the “smart” middle choice.[1]
Ever noticed this pattern in your own life?
Where You See This in Daily Life
