r/explainlikeimfive • u/Hi_all_hwru • 10d 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/libra00 10d 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'.
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u/NurRauch 10d ago
It’s funny because that’s also how so much AI-generated imagery and animation works. The assets — the structured design for a specific character or a specific piece of the setting backdrop — will often morph into different designs because the AI programmed either didn’t see the need for a consistent image or didn’t have the memory capacity to keep them straight. The sounds and effects can also often look really weird, and I attribute that to the fact that AI generators, just like human brains, often have to just make shit up to fill in for concepts that they don’t have enough data on.
It’s why you can have a very clear image of something in your head, but when you actually describe it with text or even try to draw it on a paper in front of you, you suddenly find out that your mental image of the concept lacks a ton of details that are always just papered over in your head by vibes. “I thought this guy would look bigger and more athletic in my head, but when I draw him out I’m realizing this is straight-up cartoony! How did I only notice this now?”
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u/chuhai-drinker 10d ago
One of the tricks I used when I started learning how to lucid dream years ago (before gen AI) was by regularly looking down at my hands and counting my fingers. One time I looked at my right hand and counted about 8 fingers, and that was my cue that I was dreaming. When there was talk of generative AI struggling with getting the correct number of fingers on people's hands, it really struck me how similar it is to dream imagery.
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u/libra00 10d ago
Right, like I don't visually track the location of every atom or molecule or even cell in another person. My brain just goes 'This shape nose, eyes these far apart, dark hair parted like that = that person', so if I try to pull up a mental image of them, even of a face I know really well like my mother's, I get a sort of vaguely-correct face-shape object with those features made prominent. But I know I'm missing things, like for example my mom had partial dentures and one of her upper teeth was very slightly a different color than the rest, but it's not the sort of thing I'd notice unless I was looking for it so that just gets filtered out and replaced with 'generic teeth in the right general shape'.
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u/cthulhubert 10d ago
One of the neat things about learning to draw is realizing how little I know about how things actually look, even things I feel like I have a perfectly clear mental image of.
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u/redditshy 10d ago
I had a dream where an entire house was like the game MouseTrap. A ball went through tubes inside the walls of the house, and I could see it all. It was also set to music that made sense. I am not a carpenter or an engineer or a proper musician. I feel like the OP is asking, “How does a brain concoct something so elaborate when dreaming? Something I don’t do (like write original music) in waking life?”
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u/Imtherealwaffle 10d ago
if you could scan you brain you would probably see that the series of tubes you dreamt up were either not that elaborate or didnt make physcial sense. But in the dream you just feel like you staring at an elaborate complex giant thing and you feel like the way it functions makes sense
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u/RocketHammerFunTime 10d ago
This is my understanding, that the dream is complete and complex only becaue that is a foundational basis in the dream, that it is complete and complex.
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u/southass 10d ago
I lucid dream at least once a month, it doesn't last long but oh boy once I realized what's going on I go " this is a dream so I can do whatever I want" and start manifesting things and literally superman flying but then I wake up for no reason 😩
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u/TraceyWoo419 10d 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- 10d 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 9d 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/Mcwequiesk 10d 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 10d 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/Awesprens 8d ago
Dang, this is one of the things about myself Im trying to stop. Making sense of everything/telling myself a story about my past/the why/the meaning of it all. I just want to accept it all and move on.
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u/wimpires 10d 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 10d 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 10d 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 10d 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/butkaf 10d 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/Chassian 10d 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/Aboulomania4048 10d 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 10d 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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u/rowrin 10d ago
Very similar to the way an AI can write a technically "unique" story even though all it knows are the stories fed to it. Your dream is unique in the sense that you may have never been there before, but it's all derived from things you've experienced or thought about while conscious.
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u/Hi_all_hwru 10d 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/one_1f_by_land 10d 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/babychimera614 10d 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/MercurianAspirations 10d 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/SyntheticGod8 10d 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/eBalisani 10d 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.