Cialdini notes in the first chapter, Weapons of Influence, that "a well-known principle of human behavior says that when we ask someone to do us a favor we will be more successful if we provide a reason." He cites a study by Harvard social psychologist Ellen Langer that demonstrates the power of because.
Langer conducted a study by attempting to cut in line at a library to use a copy machine. When the phrase "Excuse me, I have five pages. May I use the Xerox machine because I'm in a rush?" was used the success rate was 94%. However, when no reason was given and the subject just asked "Excuse me, I have five pages. May I use the Xerox machine?" the percentage dropped to 60%.
By itself, this is interesting but not really that surprising. The fascinating piece of the study is the third phrase that Langer used. The subject said, "Excuse me, I have five pages. May I use the Xerox machine because I have to make some copies?" Note that there is no information added to this phrase; the purpose is simply restated with the word "because". You would naturally expect this to be closer to the 60% success rate, but it was 93% effective.
The simple truth is that if there is a reason for something, almost any reason, then people are more likely to respond the way we would like them to. "Because" is a powerful word and one that can be utilized wisely by authors selling their books. Here are three easy ways to incorporate this piece of psychology into selling books.
1. Know, and say, the reason why people should buy your book. You should buy my book because . . .
2. When you are writing your book, keep this principle in mind as well. What makes your book different from others? Have you stated the reason for that clearly and succinctly?
3. Use "because" in your print advertising. Whether it is on the back of the book, online advertising, or print advertising the word "because" can convert interested lookers into readers (and potential fans).
You should use these tips because they will help you sell more books. Also, pick up a copy of Influence, The Psychology of Persuasion. It is excellent material.