"Humans have a fundamental need to be consistent in their beliefs, feelings, and behaviors. To contradict ourselves is a sign of irrationality. This is why skilled negotiators will often try to get verbal commitments from the other party as the negotiation progresses. If a person agrees to something they are motivated to behave in a fashion consistent with this verbal commitment. When negotiating, be careful to what you agree to during the negotiation. It is better to state that your agreement on a particular issue is contingent upon how the parties agree on the other issues. See Tying A String"
