An article on Listverse offers an interesting take on how sometimes it’s worth losing our cool. Though one reason it’s interesting is that it’s also pragmatic. Here’s one section:
Negotiating is all about being levelheaded and outsmarting your opponent, right? Not entirely. All of our interpersonal interactions function on an emotional level as well as an intellectual one. Research shows that sometimes getting mad can help your case. People are programmed to be cautious around someone who is angry. Therefore, it can make the person whom you’re haggling with more cooperative if you get upset—they’ll try to give you stuff to appease you.
However, there are a few caveats to all of this. First of all, this usually only works with Europeans and Americans. Asian cultures find displays of anger during negations to be rude, so blowing your lid may hurt your case. Second, if you do get angry, it has to be real anger. If the guy opposite you thinks you’re faking it, they’ll actually increase their own demands. Researchers say that faking anger erodes trust. If they find out that you’re trying to game them, they’ll be less cooperative.
Go on. Read the full piece for the other nine points.