However, if you have super high perception, maybe you do notice. Maybe when a person looks to the north to see anyone there, you catch a glimpse of them looking north. Maybe especially if you are addressing them.
Could lead to a lot more, "Take a viddy, baka, it'll last longer." moments which are always entertaining. Could also have to do with the other person's agility, if they're real sly you might not catch them looking. I dunno, thoughts?