Over at the UFO Iconclast I'm reading Rich Reynolds' OLiver Sacks, Hallucinations, and UFOs and here was my response.
Rich what's a way of finding out what's at the bottom of a pond?
Stir it up with a stick and see what floats to the surface.
This's the method they're currently using on Mars except the stick's a laser and the pond's Martian rocks.
It's also the method they're suddenly starting to realise's long been neglected in neurology thanks to a blanket prohibition on drugs like LSD.
It also seems like the reason why Oliver Sacks's long had an insight into people seeing weird stuff's precisely because once upon a time he used chemical sticks to stir up the contents of his own brains.
And this's a long and venerable method of research. Even Barry Marshall only won acceptance of and the Nobel Prize for his decade long 'discredited' insight bacteria can cause cancer by injecting himself with the stuff.
The joke of it is people set great store by 'normal' perceptions but the fact the majority of people have them only conceals the simple truth they're as hallucinatory in their own way as Sack's most extreme visions.
I was once told by an art teacher I'd drawn a vase and the wall in the background wrong. When I turned the vase upside and traced the outline of its mouth everyone could immediately see it was a factory misshape. A setsquare showed not only was the wall not straight but the plasterer'd left bulges. In other words I'd drawn what I'd seen whereas he'd been wanting me to draw what he expected me to see.
Video game makers and movie animators ran into exactly the same difficulty when their audiences rejected perfect faces. It was only when they made adjustments for the fact the eyes and other elements of human faces are actually quite remarkably misaligned and poorly symmetrical and the human brain unconsciously adjusts our faces' crookedness until they seem normal they were finally able to put out product acceptable to their audiences.
We do the same thing when we look at our parents for the umpteenth time but suddenly notice how considerably they've aged. In other words we've been filtering out their actual faces for a model in our head.
Even when Sacks sees his coffee turn purple then green if we all were prone to that condition we'd think that was how coffee was supposed to appear.
And even when people see coffee as it's 'supposed' to look that's just another hallucination because most people think they're looking at something brown but as many an artist'll tell you not only is coffee a million different shades of brown but there's all manner of other colours reflected in there not to mention light effects and one's own face and any number of objects on the ceiling etc etc etc.
As one who has spent decades reading the literature (for a time at university) I can state for a fact most of the neurological literature you refer to's actually only regurgitations of other researchers but even when it isn't it's records of people reporting actual experiences evaluated by the writers on the basis of whatever paradigms or models their universities've ingrained in them as credible. In other words just like UFO research if a detail doesn't suit an explanation's devised to justify disregarding it.
And I know this from personal experience because when I was in my late teens at the end of the Seventies and I was trying to describe to a bunch of psychiatric and neurology people about the weird effects my body was undergoing all I got out of their ringleader most of the time was "Never heard of it! Never heard of it!"
Forty years later though I note they finally have!