Misery is psychology's stale bread and rancid butter. The field heaps attention on sadness, fear and anxiety, and their psychiatric cousins depression, phobia and neurosis.
Anger receives much less scrutiny, but it is a fascinating emotion that is widely misunderstood. People tend to view it as a primitive, irrational, immoral and destructive force - but in many ways it is sophisticated, functional, moral and positive.
Common metaphors reveal a volcanic view of anger. The emotion is often pictured as a hot fluid or gas in a container.
We "burst", "fume" or "well up" with anger. Our blood "boils". If it looks as we can't "contain" our anger we are urged to "simmer down" or "blow off steam" rather than "bottling it up" or "stewing on it".
In these metaphors, anger exerts a hot, hydraulic pressure on our capacity for self-control, sometimes exploding out of us.
Indeed, the one mental disorder whose cardinal symptom is seeing red is "intermittent explosive disorder" - which is pretty much what it sounds like.
If we see anger as a dangerous pressure it is no surprise that we think that it is good to release it: better out than in. English poet William Blake said it best: I was angry with my friend: I told my wrath, my wrath did end. I was angry with my foe: I told it not, my wrath did grow.
This belief in catharsis - the idea that anger should be purged - is largely mistaken.
Expressing anger tends not to relieve the emotion, as the bursting container metaphor would suggest, but instead tends to reinforce and amplify it.
The misconception that anger expressed is anger relieved may contribute to some forms of violence.
There is evidence that playing violent video games increases aggression rather than working it off, and that angry people are drawn to such games because they believe in catharsis.
But research suggests a better way to reduce anger is to reappraise the event that triggered it, reinterpreting it with greater distance and objectivity.
The view that anger is hot and primitive also blinds us to the fact it is a moral emotion. To experience anger we must make complex judgments about right and wrong, justice, intention and responsibility.
We feel angry when we think we have been unfairly harmed or that our rights have been violated, and believe that these wrongs have been intentionally inflicted.
In essence, anger is the converse of guilt: the same morally blameworthy acts that make us feel guilt when we commit them against others enrage us when others perpetrate them on us.
People who are quick to anger often see malevolent intentions behind innocuous events, a tendency that resembles paranoia when taken to extremes. Experimentally-induced anger also boosts the tendency to perceive intentions behind undesirable events. An accidental bump becomes a deliberate slight.
Like paranoiacs, angry people tend to see themselves as righteous victims who have an obligation to give wrongdoers their just desserts.
The idea of anger as a destructive force also overlooks the fact that anger is in some respects a positive emotion. Although it superficially reflects an unfavourable assessment of the situation, just as sadness and fear reflect perceived loss and threat, anger often feels subjectively positive.
It is not as painful as sadness or fear, and can even be enjoyable, especially when puffed up by righteous indignation.
Anger can also have positive effects. It is an effective fuel for fighting injustice, convincing us of the rightness of our cause, and making our communications more persuasive.
It motivates us to persist in the face of adversity.
It can - up to a point - improve outcomes in negotiation by drawing concessions from others.
It can reduce pain, especially with the aid of energetic cursing. It can make us more creative.
Anger is also an at least partially positive emotion at the level of the brain.
It shares with other positive emotions such as happiness a pattern of selective activation in the left hemisphere, whereas negative emotions typically activate more on the right.
The neural circuitry underpinning it drives approach behaviour rather than the avoidance behaviour common to negative emotions such as sadness and fear. When we are angry we move towards whatever it is that challenges us, just as we move towards things we like and enjoy when we are happy.
Of course, anger can be destructive. It can spark violence and disproportionate revenge. It makes us worse drivers.
Angry rumination - brooding - taxes our body's stress response and increases the tendency for intoxicated people to behave aggressively.
Anger tends to be self-serving and egocentric, triggered selectively when bad things impinge on us but not when they harm others.
But it is not a mindless primitive instinct or a boiling emotional magma.
If we could understand this better we might get beyond the view that anger should be released in a rush of blood and find ways to regulate, restrain and master it instead.
Nick Haslam is a Professor of Psychology at University of Melbourne.