Magnificent Publications specializes in persuasive publications. We just read an excellent book on the subject, Yes! 50 Secrets from the Science of Persuasion, so far distributed only in the United Kingdom. Over the next few weeks we’ll be sharing some of its insights with you.
People are more likely to do what you want if they think that they owe you for a favor you’ve already done for them. Scholars call this the “norm of reciprocity.”
Researcher Dennis Regan conducted a classic study of the reciprocation norm. In the experiment, people who received a small, unsolicited gift from a stranger named Joe in the form of a can of Coca-Cola purchased twice as many raffle tickets from him as those who received no gift at all. This occurred despite the fact that there was a time delay between the gift and the request, and that Joe didn’t make any kind of reference to the original gift when he made his pitch about the raffle tickets.
Use the tactic sparingly. Offering things for free tends to make the recipient value them less than if they paid for them. Furthermore, favors diminish in value far more quickly in the eyes of the recipient than in the eyes of the giver.
With those caveats, you can make communications more persuasive by referring to the valuable benefits the audience has already received from you for free. This is easy for nonprofits and advocacy groups that work on the public’s behalf (“Here’s what we’ve done for you in the last six months”), but a business can also point to an occasion when it went beyond the call of duty for its customers.
Never minimize the extra effort you’ve put in on the audience’s behalf—since they’re getting the benefit for free, they’re already inclined to discount its value.
And if some time has passed since the favor you’re describing, touch on it delicately. As the authors put it, explicit reminders (“Now it’s payback time!”) are bound to fail.

