Yes! 50 Scientifically Proven Ways to Be Persuasive

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A small gift makes people want to reciprocate. People who received a small no-strings-attached gift from a stranger were twice as likely to buy raffle tickets from him than those who were just pitched on raffle tickets.

12:

Attaching no strings increases response to the message. Using the same hotel as the one mentioned in Chapter 2, researchers tried out two different versions of the sign. The first one: if you reuse the towels, a donation will be made to a nonprofit environmental organization. The second version: the donation has already been made, since the hotel trusted you’d reuse the towels anyways. Recipients of the second message reused their towels 45% more than the recipients of the first one.

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Similarities raise the response rate. A person named Cindy Johnson received a survey request by mail from someone named Cynthia Johannson. Someone named John Smith received a survey from Gregory Jordan. The name similarity in the first case (note that it’s just phonetic similarity, none of the names are the same) brought up the response rate to 56% vs. regular 30%.