How can dreams be so surprisingly stable?

[Laurelindo]

Technically, dreams are entirely made up of your own mind, your own thoughts, and your own memories; so how can they so often feel so stable? I know that dreams are "less" stable than waking life (obviously) and that they can often change in various ways - but they also tend to feel amazingly "solid" and physical, despite entirely consisting of something as diffuse as your own mind. I once had a lucid dream where I, just like pretty much every other lucid dreamer, tried making out with an attractive dream character, and she really did feel a lot like a real person - but how is that really possible? Why didn't she split in half, or turn into liquid, or warp in bizarre ways? How could my mind be so good at simulating every single part of her to such a level that it felt just like a physical human being?

[dutchraptor]

It's interesting, because the amount of information required to simulate such a situation would be immense in a conventional sense. Take the information the brain takes in every second from all it's senses, it's a phenomenal amount. To think the brain could store all this information is equally amazing, but does it store it like a computer does? Nope, because the brain doesn't use concrete stable data. Our storage mechanism, essentially allows us to store a colossal amount of situation in a relatively small amount of space by interpreting memories each time they are accessed. I remember a studied that showed the lack of accuracy of memories because we essentially rewrite them each time they are accessed. We experience the memory to an extent when we call it up and rewrite it. This alone tells us our brain is quiet bad at telling whether something real or not. So the brain doesn't need fully stable data, because we can use a mix. Instead of relying on reliving an exact copy of the real life situation we rely on utilizing assumptions to process the largest amount of the memory, and concrete experiences to fill in the details and convince us it makes sense. We already know that the brain relies extensively on assumptions. Everyone knows a boulder is a big rock, yet no one knows it's concrete shape, no one can say it has a definite texture or colour. You will instantly recognize a boulder as a boulder but a lot of features aren't even experienced yet, because you assume it's a boulder. This concept can be pushed further. How complex of a scene could you create using assumptions, well books make us imagine scenes the whole time without being told all the features of the world. Every item your mind knows is essentially an amalgamation of experiences, a set of rules which defines what that object is. A tower is a tall building, slender and made of a strong enough material to support it. Depending of the level of importance we place on an item, the amount of rules (and similarly memories stored) will be increased. For instance the Eiffel tower's shape is remembered independently, as is it's colour, size and position etc. Try to appreciate the beauty of this system. When we simulate an experience, only the most important aspects will have a lot of details, the amount we question an item is likely dependent on how well we know it, so really our experiences are catered to make them feel real. Obviously the brain is still extensively powerful, but if you take your specific dream the only important thing you were focusing on was this girl. The room could have been any room, the weather, sun's positions, DC's actions were all probably questionable at best if you scrutinized them.

[Darkmatters]

The brain is set up for narrative - that's the way we think, and it's why stories are so powerful for us. There are tricks filmmakers and writers use that allow them to get away with suggesting rather than showing explicitly, and I believe those tricks work specifically because they pretty well mimic the way the brain works. As long as there's what's known as a coherent emotional through-line, then the story elements don't even need to make much sense logically - and that's because it's the way the mind interprets things and the way dreams work. Also, going with what Dutch said, artists (of the visual variety) create a focal point where they concentrate detail and let things fade into obscurity the farther you move away from it. Not all artists do this of course, but it's another effective trick because it mimics the way we recall or experience things, and so of course also the way we dream. The focal zone of human eyes is actually very small - a circle a few inches across or so (don't quote me on that), that's where your vision is tightly focused and you can see detail like being able to read etc. Even just a little bit outside of that zone things are a blur - it's peripheral vision which is only good for making out basic shapes or movement. Then when you need detail you focus in on it and move your eyes around as necessary. All of this demonstrates that the vividness of our surroundings is largely an illusion, the brain stitches together information gathered over a period of time by moving the focal zone around and also pulls in memory to fill in what those big blurs are outside of the focal zone - you've seen them before so you know what they are (assuming you're in a familiar area). No need to focus on them all one by one every time. This also explains why we become so familiar with places we frequent that we can easily fail to notice fairly big changes - we don't need to be as observant anymore in a familiar area as we are in new territory where we tend to look around more and process a lot more visual information. So again, much of what we experience is actually 'filled in' by the brain without our really experiencing it clearly at all. And yet our experience of it seems seamless and complete. If the brain does this all the time when we're awake, no wonder it can do it so well in dreams, it's just using the same programming it always does.