All Biases

Decoy Effect

When comparing options on multiple attributes, adding a "decoy"—an option that's clearly worse than one choice but not the other—shifts preference toward the dominating option. This violates rational choice theory: adding an option no one wants shouldn't change your ranking.

Attribute Space 2 Options
Option A (Budget)
Option B (Premium)
Decoy
Your Ranking

Click an option below to select your top choice:

Option A
$60
Quality: 6/10
Decoy
$70
Quality: 5/10
Option B
$90
Quality: 9/10
1
Select your top choice
Without Decoy
With Decoy

Without Decoy

52%
48%

With Decoy

25%
74%
1%

Without the decoy: Options A and B have a tradeoff—A is cheaper, B is better quality. Neither dominates. People split roughly evenly based on what they value more.