To use communication skills to get a person to change from a negative behavior to a more desirable one.

In crisis situations a person’s actions is heavily based on emotions, at the expense of rationality. A negotiator seeks to reduce the negative emotions and bring back a more rational thinking process through the use of active listening, timing, empathy, rapport building, influence and control.

By strategically using open-ended questions, emotional labeling, mirroring/reflecting, silence, and paraphrasing, active listening allows the negotiator to gather information on the other person and simultaneously demonstrate empathy and rapport, thus reducing their negative emotions.

To influence someone it's necessary to show an understanding of their current emotions and behaviors; to have empathy. This can be done by attentively listening.
Building rapport involves giving the person your attention, being positive and ensuring verbal and nonverbal communication are congruent.

People in crisis often feel they lack control. By letting them talk and being a part of the negotiation process you give them a sense of control, helping them de-escalate and bringing yourself closer to your goal; voluntary compliance.

You also have to keep control of yourself, especially your emotions, as negative displays of emotion by you can escalate the situation. 

After using the other crisis negotiations skills you can pursue the final goal, to nudge someone else’s frame of mind towards a positive outcome.