“Szot changed the all-too-familiar call-to-action line, “Operators are waiting, please call now,” to, “If operators are busy, please call again.” On the face of it, the change appears foolhardy. After all, the message seems to convey that potential customers might have to waste their time dialing and redialing the toll-free number until they finally reach a sales representative. Yet, that surface view underestimates the power of the principle of social proof: When people are uncertain about a course of action, they tend to look outside themselves and to other people around them to guide their decisions and actions. In the Colleen Szot example, consider the kind of mental image likely to be generated when you hear “operators are waiting”: scores of bored phone representatives filing their nails, clipping their coupons, or twiddling their thumbs while they wait by their silent telephones—an image indicative of low demand and poor sales.”