In the past, I've written that people become angry in fairly predictable circumstances. Specifically, that people become angry when they perceive something as unpleasant, unfair, blameworthy, etc. That's prompted some questions, though, as to why some people get angry more intensely or more often than others.
As a way of answering that, I'm going to turn to Dr. Jerry Deffenbacher's 1996 model of anger where he outlines how anger results from a combination of the trigger event, the qualities of the individual, and the individual's appraisal of the situation.
To start, let's look at the simplest part of this formula: the trigger event. There is always some sort of event that happens right before someone gets angry that serves as the trigger (e.g., being cut off in traffic, being insulted by a coworker). Typically, people think that their anger is caused by these situations and they say things like, "I got mad because I got cut off by the driver in front of me" or "that guy made me so mad." The implication here is that those events caused their anger directly, and there were no other mitigating factors. Of course, we know that can't be true. If it were, everyone would respond the same way to such situations. In other words, we would all react the same when we were cut off in traffic or when we were insulted.
What, then, are the other elements that cause our anger? First, there are the characteristics of the individual--in this case, the person who was cut off or insulted. Here, there are actually two things that matter: personality traits and the pre-anger state. Starting with the personality traits, we know that there are certain characteristics that make people more likely to experience anger (e.g., narcissism, competitiveness, low-frustration tolerance). While an exhaustive review of these personality traits is well beyond the scope of this post, it's perfectly intuitive that a highly competitive person would get angry when cut off in traffic since, to them, driving may be more of a competition with the others on the road. Likewise, a narcissistic person may think of himself or herself as the most important person on the road and be irritated by the other driver for that reason.
The second part of this, the preanger state, includes how the person was feeling physiologically and psychologically right before the situation. When people are tired, anxious, or already angry, they are more likely to respond with anger. Some of this has to do with simple physiological arousal. A nervous person already has an elevated heart rate so doesn't have as far to go to become angry.
Appraisal of the situation
Ultimately, though, whether or not we get angry in response to a particular situation has to do with how we appraise or evaluate the situation. To illustrate this, let me give you an example. About ten years ago, I was seeing a movie with some friends and, even though my friend was well over 17-years-old, he was carded when buying his ticket. The interaction looked like this:
My friend as he handed over his ID: "Are you serious?"
Guy at the counter as he looked at the ID and handed him his ticket: "Sorry, but we are told to ask whenever we are unsure."
That's it. It seemed pretty straightforward to me and, though I recognized that asking for the ID was probably unnecessary, it wasn't much of an inconvenience and it was remedied pretty easily. I thought it was over until we got into the theater and my friend said, "I can't believe that guy! Can you believe he thought I was under 17?!"
That wasn't the end of it either. For the rest of the evening, my friend kept bringing it up, talking about how this guy had tried to embarrass him, how he should be fired, and so on. When I mentioned that it seemed like a simple mistake, he got angry with me, saying, "No one should make a mistake like that!"
I can't tell you why my friend felt so strongly about it. Maybe looking young was personal to him for some reason. Maybe there was something about how the guy asked for his ID that felt rude to him. What I can tell you is that our appraisals of the event were very different and his appraisal led to him getting very angry.
This is what psychologists refer to as cognitive appraisal and it's the cornerstone of Dr. Deffenbacher's model of anger. He argues that we get angry when we appraise a situation as blameworthy, unjustified, punishable, etc. In this instance, my friend had decided that this request was unjustified ("no one should make a mistake like that") and punishable ("he should be fired"). If he'd interpreted the situation a little differently (e.g., "that's a foolish request but it isn't a big deal"), he wouldn't have become so angry.
The important thing to remember about cognitive appraisal is that a person's anger-inducing interpretation or appraisal of a situation isn't necessarily inaccurate. This was an extreme example where my friend and I interpreted the situation in very different ways, and I would never go so far as to suggest that his interpretation was wrong and mine was right. In fact, as I've argued in previous posts, sometimes people are absolutely correct in their appraisal that they have been treated unfairly and, in those cases, anger is a perfectly reasonable emotion to feel.