Quick, what do you see here?
If you say "three circles and a line" then you are technically correct. You are also in a very small minority. Most people, even if they consciously try not to, will see a face. Go ahead. Try not to see a face there.
We are a pattern-recognition species, and that stood us in good stead as we were evolving. Those who saw some seemingly random lines but did not see the sabre-tooth tiger behind those lines were likely to have their lives end rather abruptly and would not pass on their genes. Those who saw some random lines and thought, "OMG that's a sabre-tooth tiger!" and ran away, got to live. Even if those random lines were not really a sabre-tooth tiger, they made a clean getaway anyway. "Better safe than sorry" is not just a glib clich矇 -- it was a way to live (and keep on living).
Apophenia is the experience of finding patterns or connections in random or meaningless data. More specifically, a subset of apophenia is called Pareidolia and deals with seeing or hearing things that aren't really there, such as the "face" above, or the so-called Face on Mars.
Because we have evolved to see patterns, apophenia is something that we all have to guard against, and as the old saying has it, there is a fine line between sanity and madness. Most of us take great pains to ignore that line. Probably because we see it as the first step on the stairway to crazytown.
I have a close family member who has taken that stairway. He is a diagnosed shizophrenic and he sees patterns in everything. And I mean everything, including an (to him) infinitely higher than average number of white Honda cars. It's an easy step from there for to believing that all of the white Hondas are part of a larger -- but hidden -- plan, that they are following him around and spying on him. To what end is never a question that enters the equation. It's enough that they are there, all around him, everywhere, all the time. And, because he refuses to take his meds ("I don't like the way they make me feel"), it is an untreated mental disorder and his long-term prognosis is not good. He has crossed that line from apophenia to paranoia.
The main function of propaganda, and its non-political arm, advertising, is to subtly and not-so-subtly encourage us to see the patterns where they don't exist. Nobody knows this better than Faux News. They are the hands-down experts at placing a semi-transparent grid over reality, where everything they want you to think is pre-patterned out for you. Who else could make a connection between the constitutionally-mandated legal representation of an indigent client accused of a crime and the supposed "socialist" views of someone who is now being considered a presidential candidate? (Hint: It's Hillary Clinton, who was raked over the coals for once acting as a court-appointed defense attorney in a rape case.)
And it's not just Faux News. Pretty much the entire right wing is guilty of it. How else to explain shit like the Obama-was-born-in-Kenya meme, or the Loontown Express that was Benghazi?
An admission: For a while there, many years ago, I was fascinated/obsessed with the concept of "subliminal messaging" in advertising (which is apparently a real thing), having read a couple of books by the notorious Wilson Bryan Key, and started seeing the letters S-E-X in every print ad that I saw. After a while pareidolia took over and I was able to see the letters in randomly textured things like pebble-grain leather, "popcorn" ceilings and towels. Finally I'd had enough and stopped looking for them. But amazingly enough, every so often I still "see" letters in those kinds of surfaces. They are not the infamous S-E-X these days (may be something to do with my age...), more like a random scattering of letters, but my mind can still project them. Weird.
The movie Conspiracy Theory starring Mel Gibson back before he became the living embodiment of Jerry Fletcher, his character in the film, is an example of apophenia. But in this movie, there actually were patterns but only he could see them. Maybe that's a bad example...
So I don't know. Maybe the patterns are there all the time and we are socially conditioned to NOT see them. Or not talk about them if we do see them. Or something...
Or maybe I need another drink. Or two. It is New Years Eve Day after all...
See you all in the new year and thanks for reading.
Further Reading: Programming the Nation?, Texas Sharpshooter Fallacy, Confirmation Bias, Cherry Picking, Denialism.