Quoting Ligneo Fistula:
…. and on the other hand all the neuropsychology literature suggests the 'power' of the various memories (working, long term etc) is strongly correlated with the ability to sight read, and if you have poor memory then frankly there's little you can do significantly improve one's memory. ….
I'd be interested to know a bit more what you mean (maybe a new thread) as you are very well read and I haven't seen (or looked for!) the type of literature you refer to. I just don't quite get what it means though. Does it just mean for music, or in general is it saying the ability to (sight)read well is linked to memory? And in which case, which way round would that work? Maybe memory improves reading as you learn the patterns? As far as music goes, I would say my ability to memorise is much higher than average, and yet my sight reading is about two grades lower than the pieces I play (still a big improvement that I'm very happy about, but it will never be a strength of mine when I play so much from memory). So that would appear to refute the literature, although a sample size of one is not scientifically significant …
Also, there apparently are ways to improve memory. Lots of books available that claim to be able to do just that, and I don't see why it shouldn't be an improvable skill (assuming no brain health issues of course).