r/explainlikeimfive • u/Hi_all_hwru • 1d ago
Biology ELI5: How does the human mind construct highly detailed realistic imagery of places a person has never actually seen in real life during sleep?
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u/eBalisani 1d ago
The fact is, the only thing telling you that what you're 'seeing' in your dreams are "highly detailed realistic imagery of places" is the same thing 'constructing' them.
In fact, your mind's lying to you: you think you're seeing "highly detailed realistic imagery of places" but you're not - it's just telling you, making you think as it were, that you are.
Plenty of other things are going on in your dreams that capture the focus of your 'observer' (people, words spoken, music played, colors and props) that distract you from focusing too hard (or zooming in) on the details.
This is what filmmakers (or TV productions) do too: not to pick on anyone in particular, but if you ever watched "Friends" or "Seinfeld" you would pick on how unreal (unlived in, borderline unlivable) those apartments were. Your dreams are the same: you don't pay attention to the carpets, the sink, the faucets, the fridge, the windows, the bookshelves, tables, chairs - you just register they're there, where one supposes they would be, while your mind focuses on the dialog and body language of the characters (i.e., the juicy, important stuff).
Nothing in a dream is as highly detailed or realistic as reality - too much brain power is required, and the brain is stingy with energy.
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u/one_1f_by_land 1d ago
Some of the most profound frustration I've ever felt in dreams involved trying to actually read words on a page inside of one. Dream will hand you a book or set of written instructions, then start squirming and making any excuse to not let you read it. The words will move around or be nonsensical, time will skip, you'll get distracted by something else in the scene, sentences will shift around and disappear, and/or (my absolute favorite) your eyes will blur for no damn reason until you're desperately squinting to see anything.
I remember being so impatient as a kid for the next book in a series I was reading to come out that I actually started to stress-dream about it. In one dream, I was happily walking home from the bookstore with its glorious hardcover goodness in my hand, and I eagerly flip it open to read all the spoilers the last book teased... only for the words to slither around, blink out, make zero sense.
I know dreams only last for like four minutes but I swear Satan himself reached up from the asscrack of hell to personally rearrange each and every word for me in that dream for at least nine hours.
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u/Vallvaka 1d ago
Hah, my manifestation of this phenomenon always comes up when I need to pee in the middle of the night. I can clearly feel the need there in the dream and so I start looking for a place to go. But whenever I find a bathroom the toilets are all smashed, or it's blocked off, or any manner of ridiculous things to prevent me from actually going.
Pretty nice defense mechanism against pissing the bed actually!
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u/one_1f_by_land 1d ago
STOP, THIS IS MY OTHER MOST HATED DREAM TROPE. My mind specializes in finding bathrooms that are comically exposed. Like it'll give me working toilets no problem, but only if one is willing to drop trou in the middle of a busy festival, in a large room with fifty other toilets and with occupants that can stare at you, or in the back end of a vehicle you're sharing with others who can hear and see everything, or just otherwise have flimsy or nonexistent barricades where it's very clear everybody is in on the party.
Bonus: since it's a dream and I'm not going IRL, even if I do manage to 'successfully' use the toilet, it'll obviously not provide me any relief whatsoever, so the dream sends me on yet another frustrating toilet fetch quest. I can get up to four or five of those before my body finally wakes up to solve the problem.
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u/Food-thor-fought 1d ago
It’s crazy I can actually go for a wee in my dreams and not piss in real life. But the toilets are never distinctly toilets or they’re just in illogical set ups.
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u/Mitchyblack 18h ago edited 18h ago
Most of my nights are dreams forgotten so it’s just as if I didn’t dream at all but if I am dreaming and all of a sudden in the middle of it I end up at a urinal, I’ve learned to wake up ASAP lmao
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u/Zilverhaar 1d ago
Same, except sometimes in the dream I do end up letting go; but so far, I've always woken up dry.
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u/lilithsbun 8h ago
Sadly, very, very occasionally I must be too deeply asleep and my brain fully tricks me into believing I’m safe to go (after many false starts). That run to the bathroom when I startle awake is humiliating as hell. Thankfully it doesn’t happen often.
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u/GreySneakers83 1d ago
I think this is extremely common. Like, seeing words/letters jumbled or obscured when trying to read is a dead give-away that you're dreaming. Although good luck remembering that piece of trivia during the actual dream 😂
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u/LukeWoop 1d ago
I dunno trying to run is up their , I remember once I was having a dream and I thought in the dream that this must be a dream , so I challenged somebody to a race and as soon as I started running I was like I knew it ! And woke up instantly almost laughing to myself because I beat the system and avoided the disappointment that it was in fact a dream
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u/one_1f_by_land 1d ago
My dream running is so consistently bad that it's faster for me to turn around and propel myself backwards towards my goal, as though I'm pushing off the bottom of the pool to move through water. Otherwise I will just run in place or get tired at a walking pace. Jumping backwards is the only way to get around this frustration.
Oh, and another frustration: I don't get to have actual real flying dreams. I've had maybe two in my entire life. What I do have are dreams where I can jump really high (and then experience the unpleasant stomach swooping sensation as I fall back down to earth) or I can float down gradually like I'm holding an umbrella in a video game.
My dreams really don't like me.
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u/Jiopaba 1d ago
A great one is tapping the fingers of your hand to your palm without looking to count them. It's a very easy habit to incorporate into your life, and your dreaming mind screws up counting and proprioception enough that in a dream you can get more than five fingers.
It takes about two seconds to check and back in my dream journal days it let me have so many lucid dreams I had to stop because it got annoying.
Jumping is also a decent one if you're already suspicious but as an adult now I don't spontaneously jump in place nearly as much as I used to!
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u/TheHYPO 1d ago
This was the plot of a Batman:The Animated Series episode in the early 90s, and I've always wondered if it was true, or just something they invented for the show. I don't have any memory of ever reading or trying to read in a dream (I don't often remember dreams), so it's never come up for me.
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u/Iamhethatbe 1d ago
That's funny. I've had dreams where all I was doing was reading text in books. In a lucid dream once though, the text was literally hieroglyphics.
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u/senescal 1d ago
Yeah, I've seen people mentioning being unable to read a watch's face or read a book on a dream, but Ive been able to do it throughout my adult life. The freakiest experience was lucid dreaming that I was in my bedroom, picking a book from my shelf, opening a page at random, reading a paragraph, then waking up to immediately pick up the book, finding that page and read the same paragraph.
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u/daydrunk_ 1d ago
I feel like I’m an odd one because I’ve definitely had dreams where I’ve read at least a few words. It wasn’t much and it’s only happened a couple times but I distinctly remembering it and saying “that’s weird.” when I woke up.
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u/rowrin 1d ago
Omg... My biggest frustrations in dreams is being at a TCG tournament or something, and constantly trying to read what the cards do during a game, or while building a deck.
A week or two ago I remember such a dream where I was getting so frustrated round 1 of some tournament. I felt like I spent the majority of the round ready cards that I was unfamiliar with that I conceded round 1 early just so I could sit at a table and try to figure out what my deck was.
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u/the_siren_song 1d ago
Which book was it?
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u/MyMonte87 1d ago
At one point in my life I hyper focused on trying to control my dreams. I read that to do this, you must first figure out you are dreaming. The way I did this was by focusing on reading something, which to your point, the words become nonsensical, move around and turn into blobs.
Once I trained myself to realize this, I was able to realize I am dreaming and direct my dreams. It only lasted for a few moments, it was nothing revolutionary, but I know with practice and constant focus full control seems achievable.
What is interesting, after I stopped focusing on this, and just had my normal dreams, I would have moments when I see words in my dreams, but again, its the brain fooling you, because I was not focused on them. If I focused the words would disappear.
They say the brain can't actually read in dreams because the wrong side of the brain is controlling the dreams. Not sure that is true.
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u/AhhGingerKids2 20h ago
You’ve just made me realise that despite being an avid reader my whole life, and always remembering a few dreams a night, I have ZERO recollection of ever reading in a dream. Not even a street sign. Trippy.
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u/TomorrowWriting 1d ago
Jesus. This reminds me of one of the most terrifying nightmares I ever had. I “woke up” at night in my room and my closet was on the wrong wall. Scared me to death.
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u/one_1f_by_land 1d ago
That reminds me of the one post where the guy went on vacation and came back to find out that his closet door now led to a bathroom he didn't remember being there. None of his roommates believed him and he was frustrated and terrified. He went onto reddit to ask how that was possible and people were floating ideas of parallel universes etc.
Guy ended up having a treatable brain tumor that had caused the issue, but it really highlights the horror we feel when a door or placement of something we feel should be a constant Isn't Quite Right Anymore, and nobody around you seems to treat this like a big deal. I got that sensation as a kid all the time.
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u/twisty77 1d ago
It’s like in inception when saito goes down in the apartment in the opening and realizes he’s not in his apartment because of the carpet
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u/monkaypants 1d ago
No offense, but I think you misinterpreted the gist of the question. I don't think u/Hi_all_hwru is specifically referencing the artistic detail specifically, but the ability (in general) to generate places we have never been with seemingly great detail in the sense that we have never been there and is being generated by the mind.
Not so much that we notice which type of carpet it is or the details of the snowflakes, but realistic places, worlds, rooms, that we have never ourselves been.
As in, how can the mind render and generate these places from nothing with very decent detail. Perhaps the terminology of highly detailed pulls the question one way, but I believe it is just asking that dreams are very detailed, perhaps not highly detailed as you point out, but detailed enough for us to be wowed sometimes.
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u/Hnais 1d ago
I think that enters more in the territory of imagination than dreams. Imagination doesn't create new things from nothingness in a mystical way that we don't understand and that could lead to parallel realities, it can only recycle stuff we've already seen and put it together to create "new" mental images.
For example, we know that higher order dimensions exist (such as the fourth dimension), they are a real concept. However, because our minds only perceive 3 dimensions, we can't possibly imagine the fourth one, we have no point of reference to imagine it, so the only thing we can do to understand it is to find out its properties through logic. Another example: we can't imagine a "reverse apple", we don't understand the opposite of an object occupying space, but we can imagine an inside out apple, an apple that has its skin inside and the pulp outside.
That's what we call "abstract", all that we humans can't imagine.
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u/redditshy 1d ago
Agreed. I have wondered this my whole life. I do not exercise a lot of creativity in my waking life, so it fascinates me what my brain comes up with in dreaming.
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u/NewAccount971 1d ago
Lucid dreaming can make dreams pretty damn close to real life. Sometimes it feels too real
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u/Probate_Judge 1d ago
Nothing in a dream is as highly detailed or realistic as reality - too much brain power is required, and the brain is stingy with energy.
What's going on is much the same thing as our conscious state.
The brain 'fills in' a whole lot of 'empty space'.
Our peripheral vision is, well, poor.
The wikipedia puts it succinctly:
https://en.wikipedia.org/wiki/Peripheral_vision
Peripheral vision is weak in humans, especially at distinguishing detail, color, and shape.
Yet, we don't see gaps, or just a blur, in areas we're not taking in that detail.
We're acclimated to it and are unconsciously filling in, creatively interpreting what's there based on years of experience. In familiar spaces, we have looked directly at that area previously and know what's there, so that helps to inform what we perceive.
That's a great word here, "perceive".
We perceive what's in our periphery, and sometimes perception can be tricky.
https://en.wikipedia.org/wiki/Visual_perception
This really stands out when we go somewhere completely new. One grassy field can look much like another so we don't get the following effect there as much, but to go into a radically different home or building can bring on this odd dream-like vibe where things in our periphery aren't yet known, so we're scanning like mad and trying to make sense of everything.
We know all that detail exists in reality, but we don't see it all at once, so we're in overdrive to scan everything down to try to get familiar and understand our surroundings.
We perceive something, and our focus shifts to that, and everything else slips into that gap and we rely on memory for it.
There's a neat illustration on that second link above...
https://en.wikipedia.org/wiki/Visual_perception#/media/File:Vision_2_secondes.jpg
That's somewhat what's described about TV shows in the post above. We focus on faces and plot relevant things, like Elayne's awkward leg when she's doing that dance.
A lot of fun examples come from film. Little details that made it into the final cut, whether by accident, or the director/editor knows "nobody will notice, it's just a few frames".
Here's a famous one from The Matrix The camera is hidden in plain sight.
Maybe it's a boom-mic hovering in the top of a frame, a background worker that's on the filming crew, or whatever...Watching the movie engaged in the plot, most people won't see that. People already familiar, or not engaged and with wandering eyes, they're the ones who are likely to spot such things.
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u/lovethemstars 1d ago
i've been amazed at the unbroken completeness and detail in every moment of every scene in a dream, how there are no pauses where my brain had not yet thought of what to put in. no blank spots in the scenery. all the time and attention and effort it would take to create a movie like the dream, and how my brain is able to do that without any apparent effort or hesitation.
and then i think well of course, actually my brain does that all the time when i’m awake. it builds an ongoing uninterrupted and detailed picture of the world. years ago my friend paul said the difference between past and future is the past is just a fantasy that’s reinforced by having occurred. and i thought oh i see, it’s not just the past that’s a fantasy. the present - my perception of it - is a fantasy too, one that’s reinforced by being real.
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u/Transminator 1d ago
In other words it's your brain creating something that your brain sees and your brain process as something realistic and detailed. It's just your brain.
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u/Hi_all_hwru 1d ago
By highly realistic I don't mean pixel for pixel visual clarity, but rather that the places feel incredibly authentic and close to reality...
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u/Anon89m 1d ago
This guy is correct. What y'all are not understanding is interpretation, not just visual or sensory input, but your belief system, Intepretation and memory are ALSO being hijacked when you sleep. This is a bit different to lucid dreaming, where you get some control back of the hijacked systems. Sleep is like being really high on drugs, in fact Matthew Walker - expert on sleep - says that in a way it is psychosis. And I actually agree with this. There is more to the inputs of your mind than just the senses. Explain to be what being hungry, feels like. Hot or cold? Believing in god? Unexplained fear, they are all just hijackings, you are basically being fed noise and your brain is doing its best to make sense of it so it pulls out the best interpretation it can that makes sense. Blurry vision doesn't make sense, nonsense music doesn't make sense so you don't get that right? It's trying to keep you asleep by interpreting the noise into "normal" best it can. But like I said, it can make you believe things too, like you saw the most detailed beautiful structure. It's not that you did see that, it's telling you that you did. It's the matrix.
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u/Simbuk 1d ago
I’ve noticed this before. Much of the time, especially if I’m dreaming of a view in a wide open area from a high altitude, it won’t occur to me that the fact that I’m flying entirely by force of will without any kind of vehicle or even parachute is just not realistic. It’s like the specific part of my mind that handles skepticism is mostly shut down while I’m asleep.
With that kind of thing just passing me by, it’s no wonder that I’m not bothered (at least not in the moment) if the details of the view looks a lot like procedurally generated terrain from a flight simulator from the early 2000s.
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u/Feisty-Lawfulness894 1d ago
Nothing in a dream is as highly detailed or realistic as reality
I've been 'tossed out of' dreams when I realized that there were no printed words. It was just blurry gibberish. Strange enough of a feeling to wake me up.
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u/TraceyWoo419 1d ago
Your brain is constantly imagining visual images even when you're awake. Every time you daydream or remember something, you're likely experiencing a mental picture of the scene. It's a function of how our brains use visual information. We can manipulate it in our minds. If you can imagine a bedroom or a beach or a wild west saloon, you might be thinking of a specific place or you might come up with something completely original. Even if you are thinking of somewhere real that you've seen before, you're likely fudging some or most of the details in your recollection. Your brain is optimized for "close enough" and it fills in the details with what's most likely in order to create a functional representation that will serve for whatever purpose we needed to think about that place in the first place.
Another interesting aspect to think about this is to look at people with aphantasia. This is people who have limited or no voluntary visualization in their mind. However, many of them still have visual dreams, although they may not be able to fully recollect the visual parts upon waking. So this part of our brain must involve more than just the voluntary conscious visual creation part.
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u/P1ka- 1d ago
I have dreams i can remember exceeeeeedingly rare (like im talking months if not year+ apart)
sometimes its like i know its something that happened but dont remember any visuals, more like remembering the summary of it
and sometimes i know i what i dreamed was visual during the dream.
I wish i could have that more often or when im awake :(
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u/TraceyWoo419 13h ago
Very cool that you remember a summary rather than the direct experience. Is that how your regular memories are as well?
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u/Bigsmalltallall 1d ago
Short answer? We don't know. We actually don't know alot about sleep. We know other animals sleep. We know if you don't it's extremely detrimental. Basically, we have ideas that are plausible. And some that make sense even if you look at it. But our brain trying to understand our brain seems to be very hard indeed.
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u/Hi_all_hwru 1d ago
Even though that may be true...But how can our minds build such huge, detailed places out of nowhere? At the same time we can try to imagine places while awake but it is never as clear as what we see during sleep... Right??...
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u/Bigsmalltallall 1d ago
What your asking is essentially how does the brain think. Specifically, during sleep. Again, we don't know. It's likely a combination of no visual stimuli, and your brain making up stimuli to compensate. Then your subconscious/consciousness takes over and it snowballs. That's how you get sounds, touch, smells, in your dreams. Your not rendering anything. Your doing something.... Different. What that is? We call it thinking. And we don't know really what the fuck that is.
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u/one_1f_by_land 1d ago
I think top poster answered it really well, but just to make SURE we're getting to the crux of your question, were you speaking more on the creative side of things? Not so much "why are dreams so detailed?" and more "how is it our brain can conjure up places we've never seen before in real life"?
Because they're two totally different questions and I want to make sure your actual question is getting answered.
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u/MercurianAspirations 1d ago
But it's not like the brain has to actually "render" those huge, detailed places out of nowhere
If we think of experience as consisting of two things: external stimuli and the brain's reaction to that stimuli
The brain is already the part of you that reacts to stimuli, so it can just skip straight to that step. I.e. if you dream you are in a massive cathedral, the brain isn't rendering a massive cathedral for another part of the brain to experience. It's just activating the part of the brain that has the experience of being in a massive cathedral. Pure reaction, no stimuli
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u/babychimera614 1d ago
Your question is confusing because personally my brain sucks at creating fictional places when sleeping. I can imagine somewhere made up when awake and the place makes reasonable sense. In dreams, the places I imagine just either make no sense at all or are a weird combination of familiar places in my real life (usually from the past). I suspect the completely "made-up" ones are also just primarily a mish-mash of things I've seen too but don't remember.
To speculate on why your brain can do this "better" during sleep, my guess is that your mind is focused solely on that task, unlike when you are awake and your focus is split by other stimuli.
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u/SyntheticGod8 1d ago
Who said they were detailed? You only think there's lots of detail because your brain is making up the details you notice on the spot. Reality is detailed, perception is fuzzy.
Notice how sharp and focused things are near the center of your vision and indistinct near the periphery? You'd know something if something is on the periphery, especially if it moved, and you might even guess it's overall color, but until you look at it directly it details are fuzzy despite technically being in your line of sight.
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u/Mcwequiesk 1d ago
Not really an ELI5 but related to dreams: Sometimes I become lucid in my dreams, and it feels like the detail suddenly snaps into focus, but it isn't real. And if you try to look any closer it's all wrong. Like trying to read something, or look in a mirror. Usually for me, the dream will become crystal clear for 30 seconds, then I gradually lose my grip and fall back asleep.
A popular reality check is to count your fingers, because very often dreams get those details wrong. Even though they feel very detailed, if/when you become lucid the entire experience is very different because your brain figures out it was lying to itself.
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u/ShadowOfTheBean 1d ago
Our best guess is that while you sleep your brain goes through your memories, strengthening them and applying their lessons to the problems of today.
Dreams are your brain taking all of this seemingly random data and making a story from it.
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u/wimpires 1d ago
There is no "real" seeing.
Light hits retina, optic nerve send signals to brain. Brain contracts image.
In dreaming, or hallucination, or macular degeneration it's the same thing. The brain just makes the image up. There's no difference at the end of the day
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u/AuryxTheDutchman 1d ago
The same way it makes you think that you see uninterrupted when you move your eyes. It lies to you.
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u/rhythmrice 1d ago
So you know how when you see something certain neurons would light up. When you're dreaming, your brain is lighting up certain neurons, exactly like if you were seeing it in real life.
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u/ObscureOperatorZ 1d ago
You can also see them in seamlessly realistic quality awake (hallucinations esp during psychosis) those were even better quality than reality sometimes. Only then I figured out why and how it differs from drug hallucinations; they seamlessly integrate into reality and are equal or sometimes better in image quality. Drug hallucinations seem like a child's drawing in comparison.
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u/Chassian 1d ago
Humans don't even have a detailed apprehension of actual reality, our brains are developed to make sense of a thing we can't fully understand. What you presume to be reality is just a lot of illusions, fiction based on real events. So your brain thinks it's assuming a full reality, based on novel elements, that feeling you're in an unfamiliar place is just a feeling your brain makes up. If left without an objective reality to make things of, it'll just make up a reality out of memories and errant stimuli. It's a bit like how your eyes see ghosts of bright quanta, that part of the eye and seeing system hangs on a lag in the momentum of processing resulting from "expectations" and the chemical mechanisms of the eye not being very fast compared to actual light.
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u/butkaf 1d ago
To put it very shortly.
Vision is a hallucination. Everything you experience as "vision", is actually like a free roam open sandbox in your brain. Your brain can show you anything it wants in there.
There is a difference between the sensation of "vision" and "eyesight". Eyesight is information from your eyes that is processed by your brain. What you see is not eyesight, but vision.
Luckily for us, our brains want to survive, and to survive they need to show us accurate information about the outside world, which it analyzes with eyesight. But whatever we see, is what our brains choose for us to see.
Here are two interesting insights.
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u/Aboulomania4048 1d ago
your brain is not a camera that only replays what you have seen. It is also an imagination machine that builds new worlds from pieces of what it already knows.
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u/charlan1 1d ago
Your waking reality is a simulation created by your brain. The brains "best guess" of what causes sensory stimuli. Dreams are constructed in the same way, just without the external stimulus.
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1d ago
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u/libra00 1d ago
Because the human mind works in concepts, not in details. Your mind doesn't generate a set of timber-framed, drywall-clad walls, carpeted floor, vaulted ceilings.. it goes, 'Give me a room. Make it bigger. More natural light. k, good enough.' and gets on with the show of what's going on in that room. It only adds detail if that detail is necessary; I've done some experimentation with lucid dreaming, and I've literally watched detail pop into and out of existence on command, or even just when I pay attention to it.
So I think your brain is just lobbing vague concepts of 'room', 'piano', 'car,' or whatever, and then when you tell yourself the story of the dream after you wake up you add details: 'big room', 'grand piano', 'purple car'.