How we change what others think, feel, believe and do
Get others to do as you ask of them by making some kind of promise.
Offer to give them something in exchange for compliance with your request. Promise to do something for you. Emphasize this by explicitly saying 'I promise that I...'
Promises can be both positive and negative, offering them something they would like or threatening with something that they will not like.
When you make a promise, ensure you are able to fulfil this, including having the necessary resource, influence, time, etc.
If we can go to show tonight, we'll go out for dinner tomorrow. I promise!
If there's one thing I can promise you, it is that if you do not do this, I will never talk with you again. Nor will any of my friends.
I promise to be good. Can I have the toy now?
Explicitly stating something as a promise emphasizes your intent and puts your reputation on the line. In this way, 'I promise I will...' is a more powerful and persuasive statement than 'I will...', even though the second statement is an implied promise.
When you make a promise, it is a good idea to fulfil the promise if you want them to trust you again. When you break promises, using this method will be unlikely to work as well in the future. An implication of this is that you should only make promises when you can keep them.
Promise is the 50th of the 64 compliance-gaining strategies described by Kellerman and Cole.
Kellermann, K. & Cole, T. (1994). Classifying compliance gaining messages: Taxonomic disorder and strategic confusion. Communication Theory, 1, 3-60