Why do we feel more strongly about one option after a third one is added?
Decoy Effect
, explained.What is the Decoy Effect?
The decoy effect describes how, when we are choosing between two alternatives, the addition of a third, less attractive option (the decoy) can influence our perception of the original two choices. Decoys are “asymmetrically dominated:” they are completely inferior to one option (the target) but only partially inferior to the other (the competitor). For this reason, the decoy effect is sometimes called the “asymmetric dominance effect.”
Where this bias occurs
Imagine you’re lining up at a movie theater to buy some popcorn. You’re not all that hungry, so you think you’ll get a small-sized bag. When you get to the concession stand, you see the small costs $3, the medium is $6.50, and the large is $7. You don’t really need a whole large popcorn, but you end up buying it anyway because it’s a much better deal than the medium.
In this example of the decoy effect, we can consider the large popcorn as the target that the movie theater wants you to purchase, while the small popcorn is its competitor. By adding the medium popcorn as a decoy (since it is only 50 cents less than the large one), the movie theater persuasively convinces you to give in and make the bigger purchase instead.
Here’s the catch: the decoy option is usually not intended to be chosen at all. In this example, the assumption is that no one would go for the medium-sized popcorn because it seems like a terrible deal next to the large option. While being smaller, it’s not that much cheaper, so the large looks like a no-brainer. The sole purpose of introducing a decoy option into a choice list is to make one of the original options—in this case, the large popcorn—more appealing in comparison.
