Avatar Dialogue: Dr. Who's Listen episode...so close

What if no-one is ever really alone? - Listen: Preview - Doctor Who: Series 8 Episode 4 - BBC

"Even though the avatars rule the timelines...they are just people." Dr. Who

It's a preview, but it's the closest of any video to talk about the existence of avatars. The Doctor stated the obvious, "If you are alone and talking, then someone is listening."  Though, the Doctor got the roles reversed. Avatars uses your voice to speak so you can listen, just like they did as your childhood imaginary friend. The other option avatars have to communicate is avatar talk, though few can tolerate hearing a voice in their head.  Avatar Dialogue is common, happens everyday, all around us, by everyday folk.

Below is Dr. Who's opening monologue in the Listen episode. The monologue asked the question about perfect hiding. How would anyone know there's an avatar on your shoulders, unless they reveal themselves. I recommend watching the show, even though it goes off on a boogeyman theme.

DOCTOR: Question. Why do we talk out loud when we know we're alone? (blows out candle) Conjecture. Because we know we're not.
(He writes on his blackboard.)
DOCTOR: Evolution perfects survival skills. There are perfect hunters.
(He watches a lioness bring down a wildebeest.)
DOCTOR: There is perfect defense.
(A shoal of dazzling tuna, and a puffer fish inflates itself so the nasty spines stick out.)
DOCTOR: Question. Why is there no such thing as perfect hiding? Answer. How would you know? Logically, if evolution were to perfect a creature whose primary skill were to hide from view, how could you know it existed?
(He puts his chalk down in an open book.)
DOCTOR: It could be with us every second and we would never know. How would you detect it, even sense it, except in those moments when, for no clear reason you choose to speak aloud? What would such a creature want? What would it do? Well? What would you do?
(That last word echoes around the Tardis. The chalk is no longer where he left it. It rolls on the floor to his feet and he picks it up, then sees that what he wrote on the blackboard has been replaced by one word. Listen.) 

Update: 

2016 January 10 - grammar

2021 March 20 - moved comment to updates, changed font, changed speak to dialogue, mental thought to avatar talk.