Sebenius calls this mistake "Letting Positions Drive Out Interests". It happens when a party has a set of preconceived, firm conditions and stands which blur the real picture, so that they can't see where their real interests. The course of negotiation should be a dynamic, unbiased process, where new interests may appear, that had previously been unnoticed. This mistake is a result of focusing too hard on one's own position, and not letting the circumstances evolve in any other way.
