Anger and Autism
In this study, they asked high functioning autistic and NT kids, both with an average age of 10 years, to give examples of situations where they'd felt certain emotions, and then to imagine themselves in the situation of a story character and say how they would feel in that situation. The stories were specifically designed to elicit multiple emotions, such as a kid being told that his beloved cat is seriously ill but will be better soon.
They found that autistic kids were less likely to attribute multiple emotions to the story characters - 31% of autistic kids and none of the NTs responded to every question with a single emotion. This was attributed to delayed understanding of emotions, which I think is correct. After all, they've had much less opportunity to learn about emotions, since they haven't seen their own emotions reflected in others in similar situations. (It came as a big shock to me the first time I saw that, with an autistic kid I was working with.)
However, another finding they have does not seem to me to be due to lack of emotional understanding. When asked to describe experiences of single emotions - sadness, happiness, fear and anger - autistic kids were specifically less likely to acknowledge feeling anger. All NT children reported feeling happiness and anger, with 86% reporting sadness and 72% reporting fear (both groups consisted of 20 boys and 2 girls, so gender roles may be at play here). Among the autistic kids, all reported happiness, with 77% reporting anger, 77% sadness and 59% fear, anger being the only statistically significant difference there.
They suggested that predominance of fear reactions may lead autistic kids to overlook other negative emotions. Compared to the NT boys' resistance to reporting fear and sadness in themselves, this shows up as underreporting anger.
My interpretation is quite different. Maybe a subset of autistics really don't feel anger, or so rarely that it's hard to think of an example of it. Maybe those kids were actually the more self-aware ones.
I've been told that I'm quick to anger, and that my anger is explosive and frightening to others. When they say this, they're talking about my meltdowns. But the problem is: I'm never angry when I'm having a meltdown. In the vast majority of cases, I'm terrified. Sometimes I'm sad or hurt as well, sometimes I'm feeling numb. It's never anger. It looks like anger, behaviorally, but when I look inside myself, I can find another emotion hidden underneath, trying to pass itself off as anger.
In fact, the vast majority of situations where I think I've felt angry, when I look at it closer, I realize my emotions were something else. Fear is, by far, the most common imitator of anger for me, probably because the fight-or-flight reaction can lead to defensive aggression. When I lash out, I always feel like my life depends on it. It's always been irrational so far, but that's how I feel.
About the only situation I can think of where I feel anger not directly caused by another emotion is when I'm involved in activism on a situation that is not imminently affecting me or someone I love. And even then, the anger is fleeting, replaced immediately by sadness for those impacted by the situation or dispassionate intellectual analysis of the sociological processes involved.
Another reason I think I don't feel normal levels of anger - I've never hated anyone. Hate, from what I understand, is a form of anger that is strongly focused on one person or group of people over a lengthy period of time. I suspect it's necessary to hate in order to believe in evil people, too, because those who believe in evil seem to just point to certain people as obvious examples of it (suggesting they're going for an emotional reaction instead of a logical one) and because hate seems to cause lack of empathy towards the targets of hate, and I feel empathy even for the most twisted serial killers. Normally, this would only be possible if I didn't empathize with the victims, because the victim-empathy would elicit hatred towards their attackers. But in my case victim-empathy elicits mostly just sadness and occasionally a bit of fear.