[svnt]

I don’t think this requires two halves, although it certainly seems possible that is what is happening.

I believe it only requires that your sensory and post-sensory systems be unpredictably generative when feeding to your subjective sense-making/observer. This could be provided for within a coherent whole brain.

[mitthrowaway2]

That would work for dreams of wandering through some random landscape, but I'm talking about dreams where I interact with people who seem as smart (or smarter) than me, who can tell me jokes that make me laugh.

What you describe would be like learning chess by exploring random boards, but I'm talking about dreams as self play: learning chess by playing as white against black, without any window into black's strategy. To do that well seems to require running two brain instances in relative isolation. Dreams would be the only safe time to do that, and a bicameral brain hardware would be the most straightforward implementation. I doubt my optic nerve can play chess against my cerebellum.

[juliendorra]

Is it possible that you are confusing the feeling of the dream with the content of the dream? For example can you remember and write down any of these jokes? Do they make any sense outside of the dream?

The dream may give you the feeling that someone is telling you a joke, and the feeling that makes you laugh, without the actual joke existing as a real structured text joke.

[mitthrowaway2]

I can, yes. I'm lucid enough after waking up to confirm that they're sometimes pretty good jokes, and very unlike what I'd come up with when awake. They're not comedy gold, I'm not a comedian, but they're but decent for me - and they would fall flat if you knew in advance how the setup was going to land.

I'm aware of the possibility you're hinting at; it's my default expectation for a dream to feel sensible but not be sensible. Like dreaming that I can speak Spanish fluently, but when I wake up I realize that none of those were real words. It's when this doesn't happen that I feel so amazed: when I wake up and reflect and it still feels like there must have been someone else in there with me, whose moves I was unable to introspect, but they were nonetheless coherent.

[kgeist]

I once had a lucid dream in which I attended a music concert, and the music was very beautiful, catchy, with complex professional arrangements; unlike anything I had ever heard before. Since it was a lucid dream, I felt proud that I could synthesize such cool music. But when I woke up, I couldn't remember anything to recreate it. This made me wonder, was the music truly that beautiful, or had I merely hallucinated my emotional response to it?

[encetamasb]

Both happens. Sometimes its only a feeling what covers the nonsense, other times I can remember the details pretty well (and its funny or extraordinary in other ways, like "meaning" has many layers, entirely unexpected).

[svnt]

As I said, I’m open to the possibility that you are correct, but it isn’t accurate to reduce the piecewise analogy to an optic nerve playing chess against a cerebellum.

You have multiple visual cortices that are made of roughly the same stuff as the rest of your neocortex. There is more than enough idle network/processing capacity there, given it is not being fed visual stimulus by the optic nerve, to “play chess.”