There's Yvain's Limits of Introspection post, which links to a paper on the scientific study of what we can access introspectively. Yvain isn't exaggarating when he calls it a "classic": Google Scholar lists over 6000 cites.
You may also wish to take a look at the papers citing it to see if there's anything more recent that's relevant, though from a brief glance it looked like the top results were about something else than introspection entirely. Still, there are probably more relevant results buried there somewhere.
I have decided that it would be valuable for me to read books (blog posts, articles, random conversations between smart people who store chatlogs) about introspection, take notes, and try to distill and clarify the information. This could result in me eventually giving up, or in a Luminosity Sequence: Second Edition (Now With Literature, Part Of This Complete Breakfast!), or (optimism!) me being able to sort ~90% of people into some number of categories such that their category membership tells me how to help them develop luminosity superpowers in N simple steps with exercises/therapy-ish stuff/etc.
Help me eat luminosity! I need recommendations for stuff to read. This stuff should be:
I read really fast. Don't worry about oversaturating me with recommendations, but please do say a little about why you recommend a thing (even if it's "I haven't read this, but I keep hearing about it, so I guess some people like it") and post recommendations in separate comments so people with information about the item can vote up and down separately. Recommendations for non-written things will be heavily discounted but not outright disqualified.
I would also like a supply of guinea-pigs-in-waiting for if and when I get to the point of trying the sorting or the superpower-giving part of the optimistic end state of the project.
If people want me to, I can document the process of luminosity-eating so there is a template to follow for other subject-eating projects, but I wouldn't do this by default because in general I only do things that someone would care if I didn't do them.