Have you ever been shopping in a grocery store, dutifully following your list, and then seen an item on sale? Maybe you walked through the canned goods aisle and saw a sign advertising "Canned peaches, 69 cents a can, limit 10 per customer." Next thing you know, the bagger is handing you half a dozen cans of peaches you just bought and you're allergic to them. Why did you do this?

According to the book Influence, by social psychologist Robert Cialdini, you're motivated by the scarcity principle. Scarcity inspires you to act for two reasons. First, objects that are difficult to obtain appear more valuable to you. This is why you see people camping out for the limited supply of the new iPhone. Second, people respond to the loss of something by wanting to have it more than before. Call that the "Fear of Missing Out," or FOMO.

In our business, we found that using loss language--language that implies you may lose something--is a great way to get clients off the fence. Instead of saying "book now" on our website, we now say "check for availability": implying a speaker may be unavailable. According to Cialdini, when people fear losing something, they act more quickly.

If you're a savvy advertiser, marketer, or salesperson you can motivate wafflers by using loss language with limited numbers, time limits, or censorship.

Limited numbers

Items in limited supply seem more valuable. Think of Picasso's painting Nude, Green Leaves and Bust. It sold for $106.5 million in 2010. Even though you can buy a print of the same image for far less, there is only one original version in the world, which makes it incredibly valuable.

When advertising something that's not a one-of-a-kind painting, Cialdini suggests writing some variation of the phrase "only x per customer." This is why a person buys half a dozen cans of peaches when a sign limits their purchase to 10. Or why a person who is thinking of buying a car, house, or boat will sign the contract when they see the phrase "Only x left."

Time limits

If you've ever heard the phrase "Exclusive, limited engagement ends soon," and bought something, then you've been motivated by time limits. The notion of a time limit taps into our Fear of Missing Out and works great on the millennial generation, according to Cialdini.

If you want to motivate people who are wavering to purchase your product or service--of which there is a large supply--the best way is to impose time limits. Set a deadline. Write "Act Now."

Loss language will remind the buyer they will lose money if they wait. People act much faster when they fear losing something, even if it was never theirs to begin with.

Censorship

The act of limiting information makes people want it more. This is why consumer protests are often so great for business. Tucker Max, the author of the bestselling book I Hope They Serve Beer in Hell, knows this. His marketer drove greater interest in his speaking engagements on college campuses by setting up Facebook groups to boycott his talks.

If you want to build demand for your product or service, then make your information seem limited. Not only will they want it more, they will also believe the information more if they think it is censored, according to Cialdini.

How do you write this? Just advertise your product or service as the information that "they" don't want you to have.

Two optimizers for scarcity writing

When using the scarcity principle, Cialdini states it works best when the item is recently scarce. Think of all those adults around Christmas time buying the latest sold-out toy for their kid, willing to pay two or three times the price. If the item is always scarce--like Cuban cigars--then the item is rare, not scarce and people are not as motivated to buy now.

Second, people are highly motivated by competition. Call this the realtor agent rule. When the realtor tells you another buyer is interested, you tend to act now. So using phrases like "While supplies last" will motivate people to buy now in order not to lose to potential competition.

So act now with these writing techniques. Or someone else might just steal your client.