Much of the time the only things in my brain consciously are the things I am experiencing or have experienced, and the patterns between them (people seem to use "patterns" in different ways: I mean it in the least abstract way possible, and doesn't have to do with "logic" or other such things). Sort of flowing together in both a synaesthetic way, and just in terms of how they connect to each other. I don't experience things as separate from each other, I just get a huge mass of sensations, which slowly filter into place somewhere in my memory.
I can sometimes build idea-thought on top of those experiences, but it's hard and it doesn't last long. And it feels like death if I get too engrossed in it. All those flowing experiences get 99% chopped into pieces and discarded in favor of things that are teeny and insubstantial, but that think they're all the world. (shudder)
One way I do describe this though, is in terms of climbing cliffs, or trying to fly in the clouds. Abstract idea-thought (which even the most "concrete" concepts, like "cat", are part of) is in the clouds, and I can't stay there without crashing to the ground (direct experience). Or building towers of abstract thought on top of abstract thought trying to reach the clouds, but finding that often I fall down. The problem is that most people seem to live in the clouds, and they don't know there's anything beneath the clouds, so they assume I must do things the way they do. And if they know I don't, they often presume my world is frighteningly empty. When it's rather the opposite. The only reason I continue to deal in abstraction-land is because it's the only way to communicate things to people who have different systems than mine, which is most people everywhere including possibly most autistics.
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"In my world it's a place of patterns and feel. In my world it's a haven for what is real. It's my world, nobody can steal it, but people like me, we live in the shadows." -Donna Williams