In The Science of Speaking, I present many different techniques for improving persuasion.
Here’s another technique that didn’t quite fit in the book. It’s call the “but you are free” (BYAF) technique.
Here’s how it works:
One of the experimenters approached individuals walking alone in a shopping mall in France. In the control condition, the experimenter made a simple direct request: “Sorry, Madam/Sir, would you have some coins to take the bus, please?” In the experimental condition, the experimenter added: “But you are free to accept or to refuse.” Those in the experimental condition were substantially more likely to comply with the request. Moreover, those who gave in the experimental condition gave twice as much as those in the control condition.
In a meta-analysis of 42 studies, Christopher Carpenter found that the “but you are free” technique generally results in a doubling of compliance rates. In other words, by adding a single phrase to your ask, your audience becomes twice as likely to accept it. Carpenter also found that the exact words you use don’t matter—what matters is that your audience understands that they are free to refuse your request.