Some are smeared, and some are spots

[mmcirvin]

Classic hallucinations explained as normal modes of a differential equation describing propagating excitations in the visual cortex. A couple of papers on the subject are linked here.

Comments

[ex-askesis860.livejournal.com]

Given that my personal cosmology doesn't include any supernatural features, I always assumed that Deadheads, rave kids, and migraine sufferers were detecting features of their own consciousness. I never expected to see

da(x,φ,t)/dt = -a(x,φ,t) + I(x,φ,t) + ∫ dx' dφ' f(x-x',φ-φ')a(x',φ',t)

though. To me, that's cause for so much more wonder.

[mmcirvin.livejournal.com]

They also talk about eyeball-pressure images and phosphenes generated by flickering lights.

There's also the distinction between simple images like these and more elaborate images of Jesus or talking lizards or what have you, which I assume are being generated on some deeper symbolic level like dreams, rather than as waves in the visual cortex.

[pbrane.livejournal.com]

Symbolic levels, yeah... because I've done a lot of pschedelics, and still never seen fully fleshed out images of Jesu or lizards...

But lots or swirly, rose-style stained-glass images, that's for sure...

[mmcirvin.livejournal.com]

...Also, one of the things they stress in the papers is that the spiral and tunnel patterns come from the fact that the cells in the visual cortex seems to map to visual angle with something similar to a complex logarithm. That right there immediately explains why Escher hyperbolic tesselations and the paisley spirals in the Mandelbrot set have such a powerful hippie attraction: it's all conformal mapping, dude!

[urbeatle.livejournal.com]

you might want to look at this article about hallucinations associated with macular degeneration as a contrast.

[mmcirvin.livejournal.com]

This article is characteristic of what frustrates me about Forteans: it describes something really interesting, then just uses it as an excuse to go off on the usual boring tangent about how nothing is real and everything you know is a put-on by the Man, whooooo.

Of course our experiences are an elaborate construct generated largely in the head. The interesting question is how we nevertheless seem to have some experiences that are verifiable and correlatable.

[sanspoof.livejournal.com]

Wow, yeah. Sometimes my camera blows out reds. Maybe that means there IS no color! Wow!
That is a highly cool set of papers, though.

[mmcirvin.livejournal.com]

You got a Nikon?

[mmcirvin.livejournal.com]

...The example of that that bothered me the most was one of R. U. Sirius's Mondo 2000 articles from way back when: he described Haidinger's brushes (http://world.std.com/~mmcirvin/haidinger.html) and how to see them, then explained that it just goes to show that we probably have all sorts of secret untapped perceptual powers, so scientists are dumb to be skeptical about psychics.

[mmcirvin.livejournal.com]

...Though, ever since I cultivated the ability to see the brushes years later, I admit that I've thought of it as my personal superpower. I can detect the polarization of light without external aid!! I can't read street signs without external aid, but we can't have everything.

[ex-askesis860.livejournal.com]

Another recent related example: (http://www.findarticles.com/p/articles/mi_m1111/is_1821_304/ai_82743069) "It turns out that one of the most productive assumptions of the last 40 years of biology was more complex than we thought, so scientists are dumb and OMG frankenfood!" I have trouble even listing all the reasons this article infuriates me, but it makes the same crazy left turn at the end that you ascribe to the Forteans.

[mmcirvin.livejournal.com]

There are also a comment in that thread on Sean Carroll's site from someone who seems offended at the idea that hallucinations could be something other than contact with a deeper reality. (And, anyway, if the research is correct, in a sense they are: they're a direct perception of the action of some nifty mathematics within the structure of your own head. If Riemann was inspired by them, that makes perfect sense, because some of the math involved is exactly what Riemann was working on.)

[mmcirvin.livejournal.com]

In that connection, I've also often wondered when people working on the diffraction of light made the connection to the appearance of eyeball floaters.

To digress a step further...

[sunburn.livejournal.com]

Are you familiar with the story of "N-Rays" and their discoverer, René Blondlot? (Skepdic (http://skepdic.com/blondlot.html)) I read about him in Paul Collins' book Banvard's Folly, an excellent book about 13 people who were hailed as geniuses for a time, but have since disappeared from history. Blondlot discovered and named N-Rays, which are light emanations from most things, but which can only be seen with almost-but-not-quite-direct viewing.

Blondlot's story is apparently most commonly described as a lesson in experimental design, because the N-Ray phenomenon fell apart in the face of a basic double-blind (well, let's say one-and-a-half, since Blondlot's assistant witnessed some manipulation of the apparatus) experiment, even though it was carried out without severe formality.

But I bring this up because Collins' book suggests that N-rays are an artifact of the cone/rod arrangement on the typical human retina, a compelling idea that I haven't seen on the web.

Re: To digress a step further...

[mmcirvin.livejournal.com]

The N-Ray incident is famous in the annals of Science Gone Wrong, but I hadn't actually heard of anyone trying to figure out the neurophysiology of what was going on there.

Re: To digress a step further...

[sunburn.livejournal.com]

Basically the cone/rod distribution over the retina isn't constant but, thanks to selection, has a ratio in the center of the retina, and hence your vision, that mixes color perception and magnitude perception. Around the edges, the ratio changes to favor magnitude perception, so you can detect movement in peripheral vision. One of the essentials of observing N-rays was to not quite look at them directly, and Collins or his source supposed that most likely, the same light might be perceived as brighter as it falls off-center in the eye. Innnnteresting.

Re: To digress a step further...

[mmcirvin.livejournal.com]

Amateur astronomers use that trick to see barely visible objects such as comets with the unaided eye; faint-object perception is better with slightly averted vision than it is straight on, because there are fewer rods right in the fovea.

(Also, I think it's not so much color vs. magnitude perception as it is bright vs. faint light perception. The rods are monochrome sensors, but it's the cones that actually provide the brightness information in bright light; the rods are completely oversaturated under daylight conditions and don't do anything useful. There are people with a rare condition that makes their cones completely nonfunctional; they see in complete monochrome, unlike most color-blind people, and they also have to wear dark sunglasses during the day or they can't see at all.)

Re: To digress a step further...

[plorkwort.livejournal.com]

ADDS BOOK TO CART, not that I have any time even for HPSc-related reading right now. See also: DeFillipo, Paul. "Sisyphus and the Stranger." Asimov's. Oct/Nov 2004. 54-63., which jwgh was kind enough to send me.

Also I wonder if Blondlot influenced Bruno Latour's pre-actor-network-theory philosophy about equipment and artifacts and naming.

[ex-askesis860.livejournal.com]

Duuude, you're directly experiencing part of the underlying structure of conscious experience - how much deeper do you want? A discussion for another time, but I get very frustrated with people who insist on the equivalent of hat tricks when they live in a universe full of genuine miracles.

[mmcirvin.livejournal.com]

Oh, it's Barry Commoner. Remember when he ran for President?

I admit I didn't bother to read the whole thing. Does he realize that the phrase "central dogma' was sort of a joke?

[sunburn.livejournal.com]

Just today at lunch, I was reading with my back to the winter sun while eating at Subway, and the bright white pages of my fairly new hardcover book was catching a helluva lot more light than was useful. The light, in fact, stained my retinas for a few minutes, causing me to see most things in the center of my vision as being stained green.

Point is that a green filter like that makes an initially unappetizing meatball sammich look inedible. Hence, the failure of Subway and, pro rata, fast food enterprise, to make food look good when you actually buy it are proof of the corruption of capitalism. Please buy my pamphlet, "Cooking with Karl Marx" by sending $12 and SASE to the above address.