[Errancer]

If we are looking for tests whenever we are tripping or not then sure, what you described is definitely the way to go. The categories I am drawing are not important for that. I make them to on the one hand tell people that they probably won't lose their consciousness and on the other that there will happen something more than simple "eye-filter". This middle step I find the most interesting, possibly dangerous and missing from wide-culture discussion so I want to pin it down. Especially that it is interesting feature of the mind independently of psychedelics. An experiment with tastes could be interesting but lately I simply avoid eating while tripping since I feel my stomach too vividly. Once I had to eat plain rice for some time after the trip since everything else was too overwhelming.

[IIAOPSW]

It was probably in Psychedelic Information Theory where I read the closest to the missing middle you are looking for. The visual system, being the most complex, is the most fragile and thus any perturbation is likely to manifest as neat geometry first. Most commonly this takes the shape of one of the form constants, which is pretty easy to explain as those patterns are directly encoded in the first few layers just after the optical nerve. So you randomly poke any neuron there, you'll get those shapes. Even waking up tired can cause it (hypnogognia). The next layer of distortion up has to do with the main loop structure (hypothalmus loop? its been a while my memory sucks). These sorts of distortions you might miscategorize as the first kind since they are still most often just "vfx magic eye filter". But they aren't so simple and in fact are distortions of a higher order of pattern recognition. I'm talking about effects such as a moving object appearing to be multiple places as though a strobe light is flickering. Or looking for a dot and suddenly seeing dots amplify everywhere in your view. By that point coherent speech is a bit hard to manage and focus is usually not forthcoming for any multi-step task. From there its pretty much a continuum on up to the point where understanding the difference between in your head or not also becomes a noisy signal. But that usually doesn't happen on acid. I get what you're after, I think a continuum of effect is a more apt concept.

Without eating per se, would you consider testing an assortment of tastes such as salt, sugar, whatever spices you have etc?