If you act in the next 20 minutes, we’ll throw in three extra knives, the bamboo cutting board and Martha’s Stewart’s Art of The Carp, all for three easy payments of $39.99 — order now!

Scarcity is a prime driver of human action. The belief that there isn’t quite enough of something, the thought that if you don’t “act now” you are going to miss out on an life changing event.

Retail chains and direct marketers have known this for years, it’s the reason why supplies are always limited and every night the infomercial mouthpiece only has 20 minutes to give you the opportunity of a lifetime. No matter how many times they setup the same constraint, that fact that it exists will drive otherwise reasonable people to act faster and more decisively.

The web is no different.

If you want people to buy into your product or to act on your call to action, give them a constraint — create scarcity. If the first three people to respond win a prize, or BETA invitations are only active within a 12 hour window, the odds of people participating and more importantly, participating with vigor skyrockets. I want to know that there is a reason I can’t wait, I need to know that there is a cost to procrastination and it’s your to job create a clear picture of what that cost is in my mind, so clear that I will act to avoid incurring it.

When you build any campaign that requires someone doing something start with an objective, an action and a constraint.

The objective is your result, what you want to achieve from participation and the reason you sat in a mind-numbing strategy meeting pontificating on business goals. You want more people to sign up for your BETA or buy your product or do TaeBo with Billy Blanks — it’s the net effect that the campaign hopes to achieve.

The action is what you want someone to do, whether it’s make a purchase, tell a friend or drive to Boise for Potato Fest ‘09. It’s a clear roadmap of your participant’s goals and how they should go about accomplishing them.

The constraint is the answer to the question, “why now?” It’s your response to –

• Don’t worry, I’ll do it soon!
• The Daily Show is on, maybe later?
• I really will get to it, I promise . . .

It’s how you inject scarcity and create cost in the mind of your users.

Next time you find yourself sitting around at 3AM, moments away from buying a third set of Ginsu knives, ask yourself what brought you here — chances are scarcity had something to do with it.

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