Introverts, the title says it all. Let's share our experiences and see if there are points in common.

I'll start.

As a child when I fell or had wounds I had no reaction. I would be impassive and people would think I was tough because I didn't feel pain. Other children would cry for everything. I would always appear stoic and serious.
For all my life I've wondered if it's true that I'm less sensitive than other people, since I've always been sure about the fact I do actually feel pain. Lately I've realised I totally feel pain (maybe a little bit less than the average person) but I have no spontaneous reaction to the outside.
As a child I used this as a "party trick". I would challenge older cousins and friends to inflict me pain, and they never managed to. I found pride in being perceived as some kind of monster. I felt invincible. Which I obviously was not, but yeah, children and their thought processes...

Later, as a teen, I remember slamming a guy against a wall because I felt provoked. When the more sensitive people of my classroom were worried about it, and tried to understand what happened and why, they were surprised to hear I was feeling like that, because I always appeared calm and cold. In that moment I realised there was a barrier between me and the outside world. To me my anger was clear. I even was sure it was obvious from my actions. Before slamming the guy, we actually played football, and I made tons of fouls and played very harsh. That was my way of experiencing my feeling of anger.
To their eyes those provocations were so minor that they had no impact on me, because my emotional reaction was non existent. And apparently the anger was not visible from my expression.

Other than this, feeling completely out of place in social situations like parties also made me feel like there was a barrier. Like, I would observe people have fun, chatting, dancing, while I would just... yeah, as I said, observe and feel out of place, kinda confused by an environment which was too fast paced.