[cheebacheeba]

I don't think you can.
If there's something like that going on I'd still say it was either predominately a PV thing, and maybe slight reactions from others around that tell you something/someone is looking at you.
Yknow, you see those documentaries...the deers/gazelles or whatever, all in a group, it starts somewhere, one will look kinda slightly, then a another...etc...people probably do that too, in a way, and some small part of them would consider it "stalking" behaviour, and instinctually "keep an eye" on it, while trying to go about unnoticed as much as possible, so as to not shift the focus of the "predator" upon themselves, and maybe you're like, picking it up from them.
Wow.
Getting deep.
So stoned right now.