The shipibo also see these patterns as some form of embodied tonality. In what way they reflect their sacred songs is still not clear to me, but there is a strong connection beween icaros and the sacred patterns. They use them to heal ...to defend...to strengthen.

There are two seemingly distinct kinds of patterns I'd like to talk about. I'll start with that which Guyomech skillfully identified above. I see these too, as noted especially on LSD. What amazed me about this effect as opposed to some of the other visual effects that you can get among the "lesser" visual effects is that (for me at least) it's not simply an overlay of a pattern onto a surface. So let's take cement as an example. It doesn't seem to me that the patterns seen behind the eyelids for example is simply overlaid on top of the cement, but rather it appears as if the particles of the cement itself have rearranged themselves as to display the pattern. This always struck me as being rather significant because I've felt that it implies something a little deeper as compared with wavering or size distortions. On DMT, the same chaotic textures that are ideal for creating this effect such as cement, sand, snow, etc...appear to me as more flowery, natural and organic where it the pattern appears to be a bit more synthetic with LSD. I might note that this could be a dose issue as I've never taken a heroic dose of LSD, so I think it might be likely that at the higher dose, this discrepancy might not exist.

Now I'd like to start talking about what I initially thought the OP was referring to as the watermarks. It seems I was wrong after reading Guyomech's post, but I thought that the kind of pattern I was thinking of bares mention. On a sufficient dose of DMT, the patterns that may start off as those noted above which presents itself (to me at least) as rather 2D, with a little bit of focus (i.e. simply looking at one place) begin to amass energy which they use to form themselves until the surface being studied becomes "supersaturated" with this energy as the patterns begin to erupt into the 3D/4D plane as holograms. Sometimes they're delicately translucent, sometimes they're packed with color, bordering on seeming radioactive. Sometimes they manifest into holographic machinery, sometimes it's vectors flying through the air and bounding around the room, and just the other day while I was still holding a hit in, before I could close my eyes, I was staring at my closet door which two tall and slender Egyptian statues formed and then began to rotate and part as to open a gateway of some kind. If it's the ceiling that's being focused on, then the hologram will usually begin to descend from the ceiling, unfolding in layers such that the pattern is still on the ceiling, occupying the area between myself and the ceiling and being right in my face eventually all at the same time. It really gives a fine appreciation of space and depth. It's this open-eyed interactable holographic phenomenon that I find to be so magical and interesting in regards to the DMT experience, and I believe that further study of this phenomenon will lead to some further interesting discoveries.

Ok, I'll play a little DEVIL's ADVOCATE here:

There is an assumption that these substances help us see MORE of what is really there... what if it's actually the opposite?

Our brains thrive on pattern - it's how we make sense of the world around us: thoughts, dreams, stories, music... Our brains NEED organization and pattern to function and progress. WHAT IF:

What you see on psychedelics, and what smerrel is reporting to see all around him while not under the influence, are not our brain RECOGNIZING pre-existing motifs, but rather IMPOSING pattern on irregular surfaces as a means of forcing the impression of comprehension.

Of course I realize what I am proposing here - that what we see, and hear (and feel) on psychedelics is a material response to a chaotic barrage, the brain's way of organizing the random, or the minutely organized, into larger chunks of recognizable pattern. I am not espousing this theory, but merely observing it as an alternative way of looking at this phenomenon. It fits in with a larger view of one aspect of what I believe these substances may be doing to our consciousnesses.

Incidentally, I don't see these patterns, but I do, on largish dose of DMT, see letters: mostly chunky golden-hued capital E's flying by, sometimes reversed, sometimes with an extra bar in them - a child's way of describing them, but words, of course, fail...

JBArk