I realize this thread has digressed a bit from the original post, and I realize that I'm just dropping a boatload of reading off onto you, but there's actually a lot of literature discussing the mechanisms involved in visual distortion.
http://www.math.uh.edu/~dynamics/reprints/papers/nc.pdf
This is a pretty important piece of research which shows how basic "form constants" consistently observed in hallucinations can be produced computationally by mapping the "noise" in V1 onto a topographic map of our visual field.
http://www.jneurosci.org/content/33/38/15171.full.pdf+html
This article talks about the role of cortical desynchronization in the effects of psychedelics. It's an interesting read, but mostly relevant because it provides a good explanation for why all of the noise in our visual cortex is normally invisible to us, but can become visible (due to desynchronization) after taking a psychedelic drug.
http://www.ncbi.nlm.nih.gov/pubmed/20046839
This article talks about edge detection and corner detection in the visual cortex. You'll probably have to read some of the wikipedia links I include at this bottom of this post to make much sense of it, if you aren't familiar with the basic biology of visual processing. But to put it very briefly, edge detection and corner detection, and texture detection, occur through higher-level integration of the signal inputs of multiple simple or complex cells. As such it's perfectly logical that edges and corners are the locus of hallucinations, because greater processing of the raw visual input occurs here, therefore distortions induced by desynchronization-noise are going to be most evident here. Similarly, it's perfectly logical that "textures look interesting" on hallucinogens because of the manner in which the brain adjusts input resolution when working with complex repeated forms like textures--the usual assumptions and corrections that the brain makes to low resolution visual data become amplified, causing the appearance of beautiful symmetrical patterning.
http://www.ncbi.nlm.nih.gov/pubmed/19523514
http://www.ncbi.nlm.nih.gov/pubmed/17470794
http://www.ncbi.nlm.nih.gov/pubmed/12107284
And these three articles talk about higher-level visual processing, including its effects on the perception of symmetry and the perception of motion, and the modulation of visual resolution by attention. All interesting stuff, and good background reading.
And as promised, here are wikipedia links for some basic reading on the mechanism and organization of our visual cortex.
http://en.wikipedia.org/wiki/Visual_cortex#Third_visual_complex.2C_including_area_V3
http://en.wikipedia.org/wiki/Simple_cell
http://en.wikipedia.org/wiki/Complex_cell
http://en.wikipedia.org/wiki/Hypercomplex_cell
http://en.wikipedia.org/wiki/Receptive_field#Visual_cortex
So in short.... I suppose you could say there is an "intelligence" implicit in the form of visual hallucinations, but that intelligence is your own. The cool thing about hallucinogens is they basically enable you to
physically see your own brain at work. All of the backend processing which is normally hidden from your conscious view becomes unveiled through its own disruption.
