@Fragglemuppet firstly i think often it's a suspicious or paranoid feeling you get when someone isn't in the room, so while it's a real feeling it at best has a lot of negatives and at worst is totally random. certainly there's times where people have completely surprised me and i didn't feel like that. i can imagine a lot of little signs like air movement, smells, slight lighting change etc adding up to create a sense of someone being there but i dunno if that's really at play