The Principle of Contrast

In human perception, the principle of contrast plays a crucial role, influencing how we perceive the difference between two things presented one after the other. Simply put, if the second item is noticeably different from the first, we tend to exaggerate their differences. For example, if you first lift a light object and then a heavy one, you’ll perceive the second object as even heavier than if you had lifted it without first picking up the lighter one. The principle of contrast applies to almost all types of perception.

Imagine you’re at a party talking to an attractive woman, and then a less attractive woman joins the conversation. The second woman will seem even less attractive than she actually is. Studies conducted at the universities of Arizona and Montana have shown that we may feel less satisfied with the physical attractiveness of our own partners simply because the media bombards us with images of unrealistically attractive models. In one study, college students rated an average-looking member of the opposite sex as less attractive if they had just looked at ads in popular magazines. In another study, men living in college dorms rated the appearance of a potential date from a photo. Those who did this while watching an episode of “Charlie’s Angels” on TV gave lower ratings than those who watched a different show. Clearly, the extraordinary beauty of the actresses playing the Angels made the stranger seem less attractive in the men’s eyes (Kenrick & Gutierres, 1980).

In psychophysics labs, the following demonstration of contrast in perception is sometimes used. Each student sits in front of three buckets of water—one cold, one at room temperature, and one hot. After placing one hand in the cold water and the other in the hot, the student is asked to put both hands into the lukewarm water at the same time. The look of confused amazement says it all: although both hands are now in the same bucket, the hand that was in the cold water feels as if it’s now in hot water, while the hand that was in the hot water feels as if it’s now in cold water. The same thing—in this case, room temperature water—can feel different depending on the previous situation.

You can be sure that this powerful little tool of influence, provided by the principle of contrast, doesn’t go unused. Its great advantage is not only that it works effectively, but also that its use is almost undetectable. Those who want to apply the principle of contrast in practice can do so without any obvious structuring of the situation. Retailers of fabrics and clothing are a good example. Suppose someone walks into an upscale men’s store and says they want to buy a three-piece suit and a sweater. If you were the salesperson, which would you show the customer first to make sure they spend more money? Clothing store owners recommend selling the more expensive item first. Common sense might suggest the opposite: if someone has just spent a lot of money on a suit, they might refuse to buy a sweater. But clothing retailers know better. They act according to the principle of contrast: sell the suit first, because when it comes to sweaters—even expensive ones—their prices won’t seem too high compared to the price of the suit. Someone might resist spending $95 on a sweater, but if they’ve just bought a $495 suit, a $95 sweater won’t seem too expensive.

The same principle applies to someone buying accessories (shirt, shoes, belt) for a new suit. Contrary to common sense, the facts confirm the effectiveness of the contrast principle. As retail analysts Whitney, Hubin, and Murphy state in their book “The New Psychology of Persuasion and Motivation in Selling” (1965), “Interestingly, even when a person enters a clothing store with the clear intention of buying a suit, they almost always pay more for any accessories they buy if they purchase them after buying the suit, rather than before.”

For retailers, it’s much more profitable to present expensive items first, because if they don’t, the principle of contrast will work against them. Showing a cheap item first and then a more expensive one will make the expensive item seem even pricier—hardly desirable for most businesses. Just as you can make the same bucket of water feel colder or hotter depending on the temperature of the water presented before, you can make the price of the same item seem higher or lower depending on the price of the previously shown item.

Smart use of the principle of contrast in perception isn’t limited to clothing sales. I encountered a method based on this principle when researching the “compliance tactic” used by real estate companies. To “teach me the ropes,” a company representative accompanied me while showing homes to prospective buyers. The salesperson—let’s call him Phil—was supposed to introduce me to the basics of the business to help me get started. I soon noticed that whenever Phil began showing clients potential homes, he usually started with a couple of unsuitable houses. I asked him about this, and he laughed. These houses were what he called “show properties.” The company included one or two rundown houses in their listings, with prices clearly set too high. These houses weren’t meant to be sold to buyers, but only to be shown, so that the more promising properties in the company’s catalog would look better by comparison. Not all staff used show properties, but Phil did. He said he liked to watch people’s eyes “light up” when he showed them the property he really wanted to sell, after they’d seen the rundown houses that looked like a pile of junk.

Car dealers also often use the principle of contrast. They wait until the price for a new car has been agreed upon, and only then offer optional extras. When you’re making a $15,000 deal, an extra hundred dollars for something like an FM radio seems trivial. The same goes for expensive accessories like tinted windows, dual side mirrors, or special interior trim, which the salesperson can offer one after another. The trick is to get the buyer to make additional purchases independently of each other. Each relatively small price seems reasonable compared to the much larger amount already committed. As any veteran car buyer can confirm, the final price often depends on the addition of various seemingly minor items. While the buyer stands there with a signed contract in hand, wondering what just happened and finding no one to blame but themselves, the car dealer smiles slyly like a jiu-jitsu master.