What's that strange tingling?

This is gonna sound really weird but I think I can feel other people's brainwaves. I know, I know it sounds crazy. I'll try to explain. The first I can remember it happening was back in Grade 7 or 8. My friend Pete liked to draw. (Still does) Sometimes I would ask him to draw for me. When I watched him draw I would get a strange tingling sensation up my spine and across the top of my head. When he stopped, so did the tingling. I still get that same feeling sometimes when I watch people do certain things. It happens most at work. If I am watching someone troubleshoot or fix my machine, either physically or by working on the computer, I get that feeling. However, I think that the task they are performing needs to require a certain amount of concentration. It doesn't work if they are just running the machine. That doesn't require much thought. But if they are trying to do something that requires some concentration, it tingles. But, I have to be sort of be concentrating too. If I look away, it doesn't work. I have to be paying attention and watching them. But I can't be paying too much attention. If I am actually watching what they are doing and either trying to figure it out or remember it, there is no sensation. But if I am almost casually but intently watching, it works. It's almost like I need to keep my mind slightly out of focus. Too much focus on the details blocks it. I have to "let it in". I haven't tried to experiment with it too much but I don't think it works if I just watch someone think. I think they need to be translating those concentrated thoughts into a physical action. Even if it's just tapping keys on a keyboard or pushing a pencil around some paper. It's a hard thing to test because not everyone likes being stared at when they are trying to do something. What I am trying to figure out is, I think, is there something emitted from the brain of someone translating concentration into a physical action that my body picks up on? Does that make any sense? Is it real? Or is it just some subconscious pleasure in watching people do work for my benefit that my mind has created? And my body has a physical reaction to it? It is quite weird. If it is some sort of phenomenon, how can it be explained physiologically/neurologically? It is an interesting question but I don't know how to find the answer. Maybe I should watch someone try to figure it out!