The decoy effect: the middle phone nobody is meant to buy

The middle phone is there to make the costly one look sensible.

Karan is 24 and works at a bank branch in Indore. His phone is four years old and the battery gives up by evening. A festive sale starts, and he opens the page for the phone he has been watching. Three variants sit side by side.

The 128 GB one is ₹24,999. The 256 GB one is ₹33,999. The 512 GB one is ₹34,999.

He looks at it for a while. Then he thinks: for just ₹1,000 more than the middle one, I get double the storage. He is already reaching for the top one.

What the model is

The decoy effect is what happens when a third option is placed beside two real ones, not to be bought, but to change how the other two look. The decoy is clearly worse than one option and only a little cheaper than it. Next to it, that option looks like a bargain. The idea comes from the researchers Joel Huber, John Payne and Christopher Puto, who called it asymmetric dominance.

Karan's three phones

Start with the ₹33,999 phone. Would Karan have picked it if the page showed only that one and the 128 GB phone? He says no. It is ₹9,000 more for storage he has never run out of.

So who is that phone really for? Its job is to stand next to the 512 GB phone and make a jump of ₹1,000 look small. Without it, the top phone is ₹10,000 above the cheapest one, and Karan would ask himself a harder question.

There is a simple way to spot a decoy: ask which option you would never pick yourself, and then ask which option that one makes look good. Look at the option right next to it.

Now Karan does the thing the page did not ask for. He opens his current phone and checks the storage. He is using 48 GB, and a good part of it is photos he never looks at. He needs a phone that lasts the day and holds his banking apps and a few videos. The 128 GB one is enough for that.

The decoy has not changed the prices. It has only changed which price he compared them to.

The same shape sits in a multiplex, where small popcorn is ₹180, medium is ₹320 and large is ₹340.

The trap

Not every middle option is a decoy. Sometimes a mid-size pack is simply the one that suits a family of four. Calling every middle option a trick makes you suspicious of a fair price, and that is its own mistake. Ask what you needed first, and the decoy question gets easy.

Also, the model does not tell you which phone to buy. The 512 GB one may be right for someone who shoots videos for work.

One thing to try today

Before you open the next sale page, write one line: the size or variant you need, and why, in a number you can check on your current phone or in your kitchen. Only then compare. If you end up on a different option, write down what changed your mind. The first time will feel slow, and the line may feel silly.

This is a way to think, not financial, medical or legal advice.

Each Sunday: one mental model and one real decision to try it on. The whole library is at /models.