If somebody says something sarcastically, I may completely miss their intention. When people are being sarcastic, my mind tends to focus on the literal meaning of the words. If they are being blatantly sarcastic, I can understand that they don't intend the literal meaning of their words. However, my mind still tends to focus on the words said, even though I understand that's not their intention. In most cases, this feels quite uncomfortable.
If people are not as blatantly sarcastic, I think I sometimes pick up something in the way they are talking which doesn't sound quite right. The tone of voice doesn't quite match the literal meaning of the words which my brain is interpreting. This also causes confusion and unease.
If someone is being sarcastic, but is speaking with a very straight face, I simply hear the literal meaning of the words and don't understand their intention at all. It seems to me that this is one of the main problems with a social interaction where someone is kidding me. I hear the literal meaning of the words, which sound as though the person does not like me, or does not wish me well. I don't hear the intention behind it, which is being conveyed by their face or their voice.
After seeing so clearly all of the aspects of communication which are conveyed by facial expression and tone of voice, I certainly understand why many people with Asperger's have social anxiety. In some ways, it is as if you are in a foreign country, and aren't completely fluent in the language. The people speaking to you don't know that you don't speak the language, and they expect you to understand what is being said. Your experience is one of trying to understand what is being said, and having to translate what is being said so that you can understand it. It can be anxiety provoking when people expect you to be able to react in a way which you are not able to do. There's certainly a lot that gets missed or misunderstood. It's also very tiring to have to constantly try to figure out what is being said, and to be wrong too much of the time.
I have great hope now that the researchers are finding some specific areas of the brain which are affected in autism spectrum disorders. As they are able to refine the stimulation techniques, they may be able to influence the brain in ways that can permanently improve communication. As I have just seen, this could be a life-changing experience for many, many people.
For more of John's insights check out his blog Look Me In The Eye.