Yeah, it was the 'serotonin/depression' thread. I think that the theory is interesting enough, from the perspective of anyone who's interested in the psychedelic experience and possible explanations for it, to have a little thread of it's own.

You're right that the theory isn't perfect. I think there's probably a lot more two-way traffic going on between differen layers. After all, to have a good understanding of what's going on around us, we also need to 'look back' every now and then. For instance when sensing motion, like objects moving with great speed. If we could not 'go back in time', then, as our brains aren't that quick, we would probably perceive such objects as not one object but as a series of unrelated objects 'popping in and out of existence' on a series of different locations.

There actually is some sort of brain dissorder that causes people to experience motion that way. Must be confusing.

What you're suggesting probably comes down to the same thing indeed. I think the reason why the predictive coding theory focusses so much on this 'layer thing' is because of it's application in A.I.

But the theory can also be seen as an integration of what you're suggesting, and the 'modular thinking' that has become fashionable in neuroscience.

An interesting aspect of predictive coding, is that the predictive coding mechanism in a sense also encompasses itself, like in a weird escher loop. The brain also learns to predict how accurate it's predictions are going to be in different circumstances: when you're in your own home at night, then predictions are probably going to be very accurate. The need for error-detection is less great then. When you're in a dark place you've never been before, the error-detection 'device' is probably becoming a little more active.

I don't know if the implications of this are that, the more often you take hallucinogens, the deeper you'll be able to delve into the experience. I suppose that most people here probably do experience it that way.