> then isn't the experience just of "a surface attribute, of given spatial extent".

I don't know why this seems to be so hard for me to think about and even put into words, but isn't "the experience of the surface attribute of a given spatial extent" something other than the experience of the surface attribute of a given spatial extent itself?

I mean that the words we use to describe something aren't the something itself. Conceivably, you can experience something without ever having words, and having words about a phenomenal visual experience doesn't seem to change the experience much or at all (at least for me).

Maybe another way of phrasing this would be something like: can we talk about red blotches using red blotches themselves, in the same way that we can talk about words using words themselves? And then, supposing that we could talk about red blotches using red blotches (maybe the blotches are in the form of words or structured like knowledge, I dunno), can we talk about red blotches without ever having experienced red blotches? I learned this idea from Mary's Room thought experiment, but I still don't know what to think about it.