How do we

know when someone is watching us? This happened to me the other day where I instinctively turned to look at someone

who was staring at me.

I used to think that it had something to do with pheromones, but I am not so

sure.

I've conducted experiments where I would have someone behind me look away and then I would indicate

when I believed they turned to focus on me. I got it every time, fairly immediately.

This is obviously some

sort of human survival skill or something, I'd like to know what are the mechanisms involved in it.