I instinctively feel there could be more than a nugget of truth in this proposition
@GNC
Generally, mortal humans display possession of their own corporeal interiority via movement / gesture and sub-conscious signalling in a vast multitude of ways, beyond the monodimensional medium of speech.
Non-native speakers of a focus language, stroke victims, and certain high-functioning neuroatypical individuals, display either markedly-reduced (or nil) facial expressions, including blinking. There is a well-documented psychological literature that maps how NT humans cue and clue each-other via face-reading, at levels of instinctive complexity
way beyond the primate baselines of arched eyebrows and projecting tongues.
I could so easily imagine that an observed spirit (irrespective of what that means) would
never display any of these biotelegraphic back-channel subtleties. I don't mean that they wouldn't blink, in the way that an almost-perfect android might not blink: I mean in the sense that we, as mere mortals, know that spirits are there to inform/dictate/dissaude
towards us, with us as recipients, never peers - it
isn't part of the fundamental presumed compact of the encounter that they'll intimately interact with us.