When a person makes a public commitment to a course of behavior, the human psyche will push them to follow through with their commitment. For instance we break New Years resolutions because we seldom share them with others and usually do not write them down.
An interesting phenomenon occurs when the commitment is made public or a person pro-actively takes the first step to follow through with a course of action. An interesting research study found that although people are often unsure of their choice of the winning horse at a racetrack, they become much more confident of their choice once they place their bet. They are driven to consistency once they make a public commitment to a course of action.
Therefore experienced negotiators and mediators focus on getting people to publicly verbalize and/or write down each small commitment to follow a certain course of action (e.g. buy a car or resolve a dispute) knowing that once done publicly, it is highly likely that they will believe this is the best choice and will find a way to attain the object of their commitment.