Okay, let's start off with a disclaimer (because those are super interesting) but in case you're new here, let me tell you that I'm really, really not an expert on psychology. I might qualify as an expert on writing, but at this point that would only be because I've been studying it in all my spare moments for more than a decade, and eventually I had to have absorbed some of it.
So if I'm not an expert on psychology, why am I writing about it?
Well, it's because I think it's super interesting. So let's get down to brass tacks with something we've probably all heard before:
"If you want to remember something, write it down."
My mom told me (I can't even think how many times) that if I wanted to remember something, which I was notorious for not doing, then I needed to write it down so I would remember.
But why does this work?
Buckle in, kids, because we're going to ride roughshod over some very complex psychological facts.
In the simplest, most memorable way I can put this: There are separate areas of your brain for handling different kinds of information, whether visual, kinetic, auditory, linguistic, emotional, etc. and so forth. While they talk to each other, they are all separate things. It's like your phone and your computer talk to each other, but they're not the same thing and sometimes one knows things the other doesn't and everything goes to pot next time you're looking for that specific thing.
The same thing happens in your brain. You look at a piece of art and have an emotional/visual reaction to that art, then translate it into linguistic information so you can tell someone else how it feels, but you always lose something in translation.
But Ink, what does this have to do with writing things down?
I'm getting there.
Information that we gather from the outside hits several points as it's processed in our brains. We watch something happen and maybe it has sounds that go with it - like watching the rain fall. There's more than one kind of information being processed, but they're linked and you brain will say "Okay, so the sound of rain falling is tied to the sight of rain falling and that smell I don't have a linguistic name for where everything is wet and clean." (That smell is called "petrichor," by the way - impress your friends at parties!)
So the reason we remember the experience of watching the rain fall so clearly is because it's tied to several different things.
Ah-ha, you say. I get where you're going with this. So I remember things better when I write them down because I'm tying the memory to more things.
Yes. That's exactly it.
This is especially important with things that take place entirely inside your head, like inventing a fictional story. There are no sights or smells or sounds tied to inventing that story, so writing it down will anchor it to an experience that will help you remember it later on. Or at least you can go back and read your notes and remember that way.
Pro Tip: If you want to remember an experience or place or something very clearly, tie it to another memory. Wear a new perfume for a vacation you never want to forget. Listen to new music or eat new food with a person you want to remember. Compose your fictional story or worldbuild in a new location. While you're forming memories of that smell or that taste or that place, you'll also be forming memories of that person or that experience, and you'll be able to trigger memories later on by smelling that perfume or tasting that food.
It may not work for large chunks of information like studying for a test, but you'd be amazed what your brain can do when you make it work together.