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Persuasive Web Design, Part 21: Using Contrast (and Decoys) to Influence Decisions

We don't like to evaluate products in a vacuum. We prefer — even need — to contrast and compare products to other, similar products.

This principle applies to all product attributes: taste, smell, attractiveness, etc. Just to keep it simple, let's stick to an easily quantified attribute: price.

Logical Online Persuasion

Say you're looking for an outboard motor. You find a 20 HP Motor for $1,900. Is this a good price?

It's hard to tell, isn't it? Your first response is, “What do other makes and models sell for?”

Now assume you're shown a list of prices:

  • 10 HP Motor, $1,600
  • 20 HP Motor, $1,900
  • 25 HP Motor, $2,700

Does the 20HP Motor for $1,900 seem like a good deal now?

You bet it does: It's only slightly pricier than 10 HP motor, but has twice the power. And the 25 HP engine, which is only slightly more powerful, costs almost 50% more. Easy decision, isn't it?

The above seems simple enough. And logical. But let's take it a bit further… and see how logic breaks down.

Crazily Irrational Persuasion

If you were flirting with the idea of subscribing to The Economist, which offer would you prefer:

  • Web Only $59
  • Print and Web $125

Dan Ariely conducted just such an experiment.* Given the above choice, only a minority — 32% — opted for Print and Web (which is what The Economist really wants to sell).

Then Dr Ariely put in a decoy. (To be precise, he put it back in. The clever folks at The Economist had actually used this technique in a web advertisement.)

  • Web Only $59
  • Print Only $125
  • Print and Web $125

The decoy (Print Only for $125) looks so bad, you might think it was a mistake. Why would anyone choose Print Only when they can get Print and Web for the same price?

They wouldn't. But it's no mistake. It's there for the sole purpose of making Print and Web look like a bargain.

And it works. With the decoy in place, 84% opted for Print and Web.

Think about it. The percentage who chose Print and Web rose from 32% to 84%… yet nothing had changed! The offerings and prices were exactly the same. The only difference was the decoy, which of course nobody took.

It's not rational, but it works. Products look much better when placed next to similar but less desirable products. Better not only in comparison to the less desirable product, but better overall. It's a kind of “halo effect”.

Using These Principles to Make Your Website More Persuasive

On your website, you control the comparisons. For best effect:

  • Don't price items in a vacuum. Let customers compare prices and features to other, similar items.
  • If you only sell one product (or one product in a given category), add one or more additional products — even if only as decoys. Customers need comparisons.
  • If there's an item you really want to sell, place it next to a similar but less desirable option.

Finally, remember the “halo effect”. By adding an intentionally bad option as a decoy, you can make a product appear not only better than the decoy, but better overall. Used properly, this is one of the most diabolically effective online persuasion techniques available.

* See Chapter 1 of Predictably Irrational.


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