Here's a metaphor we've been using a lot at Rationality Boot Camp: People's behavior is controlled by an elephant and a human rider -- the rider represents your rational, cognitive, high-level thought processes, whereas the elephant represents your emotions, habits, and unconscious thoughts. The metaphor works well: the proportions are about right, and when the elephant and the rider conflict, guess who wins.
One practical technique we've been studying is Nonviolent Communication (NVC), a buzzword-driven methodology for communicating with people, which focuses on ways to defuse upsetting situations. Someone called it "elephant whispering". The idea is that if someone is angry with you, or frustrated, or whatever, their elephant is going crazy, and you can help tame it so their rider can get back in control.
The main technique we're learning through NVC is empathy. You can derive utterances which will reliably calm an upset person down and engage their cognition. The elephant apparently responds very well to this sort of empathy. This is as opposed to a number of common ways people try to talk to upset people, which don't usually work as well. Don't do these:
Instead, the technique says to talk only about: "observations, feelings, needs, and requests." Observations are factual statements, "You left the light on last night" (what not to say: generalizations or evaluations, like "you always leave the light on").
Feelings are observations about emotions. Things like "angry", "confused", "disappointed", "frustrated", "sad", "embarrassed", etc. There are also positive feelings: "hopeful", "intrigued", "proud" and so on.
"Needs" refer to basic human needs which our elephant wants: self-worth, food, rest, love, creativity, order, respect, etc.
And requests are from one person to another, reasonable things to ask of another person, like "turn off the light before you sleep" or "knock before you enter".
You can leave off several of observations, feelings, needs, or requests if they don't apply. You can also take guesses as to the cause. If you successfully signal curiosity, the other person won't get more upset, even if you guessed wrong -- instead, it will trigger them to correct your guess, but in the process it will engage their rider and naturally defuse their upsetness.
For example, if your roommate stomps into the kitchen and won't talk to you: "Are you upset because the kitchen isn't clean?" Even if you're wrong, more likely than not, your roommate will figure out her reason for being upset, and should become less upset and more willing to talk.
There's a lot of good examples and information on wikihow's article.
My evaluation? When I imagine some of the confrontations I've had, I can easily imagine NVC working. The instructor, Divia, says that her interpersonal relationships have massively improved with the use of NVC. For these reasons I am inclined to believe that it works, with fairly high uncertainty until I have put some of this stuff into practice. In any case, let me know if you've had any experiences which would show that it works or doesn't work.