Weird Sense?

[nastrow]

So I've noticed that if I'm attracted to a certain girl, I basically get eyes for her in the back of my head. For example, today I was swiping my ID at the desk to go into my dorm and for some reason while I was swiping I turned and looked at the door (way to the left) , where this girl I like had just walked in. The strange thing was I didn't look because the door opened, it was way after I heard the door but before she was in my peripheral vision. Plus, there were other people who were leaving the elevator who I'd already seen, but they set a sort of screen so it wasn't like she was the only thing moving in that direction. I really still have no idea why I looked over there. I kinda freaked out a little when it happened; it was funny. Occasionally this will happen where I look completely behind me. Does this happen to everyone? Is it something subconscious? It's not like it really bothers me I just find it weird as hell sometimes.

[Maoky]

You're just noticing because you want to. Like you said, there were other people and things there to see, but you decided to pay attention to her. There's probably hundreds of other times in the day when you could be inadvertently looking at someone or something, but you don't recall it because you're not interested. Our eyes/brain tends to filter out a lot of background information (called 'noise' in psychophysics). Ever seen that illusion where you stare at a dot in the middle, and the circle around it disappears? Imagine the girl you fancy as that dot, and everyone/everything else as the background circle. You just notice her because she's worth noticing haha =)