being alone plays strange tricks on your mind.over at the wilderness canoeing site people who go out solo always post "i felt like i was not alone" messages or "felt like i was being watched" and of course others chime in with the "Ya,me too".
people in distress like stranded mountain climbers not only feel but see someone.maybe it's some sort of survival method wired in our brain from a few million years ago,i think it's stress hallucination and in less stressful one's just a overwhelming sense of self.