Carl Sagan wrote about this in The Demon-Haunted World I believe. I recall him talking how in the middle ages, before any UFOs or alien concepts came to be, people saw witches, demons, succubi, etc. Then the "scientific era" came to be and people started to see more "aseptic" images, i.e. aliens wearing lab coats, or other "science-y" stuff.
When I read it, it made a lot of sense. It is quite obvious if you look into it, that people's hallucinations or visions are strongly correlated with their current culture or world view. So you if you see something inexplicable, you are going to call it a ghost for example, but a medieval knight will call it a demon, but maybe someone from 2100 will call it a perturbation of the higgs-field or whatever makes sense then.
When I read it, it made a lot of sense. It is quite obvious if you look into it, that people's hallucinations or visions are strongly correlated with their current culture or world view. So you if you see something inexplicable, you are going to call it a ghost for example, but a medieval knight will call it a demon, but maybe someone from 2100 will call it a perturbation of the higgs-field or whatever makes sense then.
Quite interesting effect actually.