Behavioral scientist Ellen Langer and her colleagues decided to put the persuasive power of this word to the test. In one study, Langer arranged for a stranger to approach someone waiting in line to use a photocopier and simply ask, "Excuse me, I have five pages. May I use the Xerox machine?" Faced with the direct request to cut ahead in this line, 60 percent of the people were willing to agree to allow the stranger to go ahead of them. However, when the stranger made the request with a reason ("May I use the Xerox machine, because I’m in a rush?"), almost everyone (94 percent) complied…
Here’s where the study gets really interesting…This time, the stranger also used the word because but followed it with a completely meaningless reason. Specifically, the stranger said "May I use the Xerox machine, because I have to make copies?"
The rate of compliance was 93 percent.
That is from Bob Cialdini’s Yes! 50 Scientifically Proven Ways to be Persuasive; here is my previous post on the book. And here is why motivational posters don’t work.