I don't actually know though, this is just my understanding.
It affects my vision rather negatively and the darkness magnifies the effect immensely making it hard for me to be aware of the countours of objects.
There are forums on the net were people experiment with various drugs with bizarre effects, spontaneous healing or no improvement at all were others see immediate effects.
My doctor send me to the optometrist, his assistant wondered why he didn't send me to a neurologist, the optometrist dismissed it because there wasn't anything wrong with my eyes.
Take a look at https://en.wikipedia.org/wiki/Entoptic_phenomenon
If you are having progressive vision problems that worsen your quality of life, consider being persistent in voicing your concerns and perhaps visit an ophthalmologist.
For me its like constant tv-like static that is mostly transparent but makes the outlines of everything slightly blurry. Ranges from almost not visible in good natural lighting conditions to very visible flicker in dark enviroments or places with lots of artifical light sources.
Never did any illegal drugs, dont smoke, dont drink alot of alcohol and workout regularly. Brain scan and everything was OK.
It started after 2 years of psychologically very taxing situations like a failed startup, failed long-term relationship etc. Dont know if its related to that, but it could...i am fine now and its still there though.
Another reminder to not constanly overwork/overstress yourself, many people dont realize in what ways your soul and body might react that you might not be able to reverse.
Anyway, visual field deficits can be brain-lesion-driven, as you say (e.g., the classic bitemporal hemianopsia in pituitary tumors).
In their case the doctors didn't remove it because the operation would have been more dangerous than the tumor itself, and the symptoms were not too severe. But it's obviously better to be aware of such things.
ElongatedTowel ought to go to the doctor and deal with a few weeks of feeling like an embarrassed jerk by demanding that they scan his/her brain.
For the longest time, I wondered if people saw a "static" overlay like I do. Talked to my optometrist about it last time and he wasn't aware of this condition. Googled it later and there is some research starting on the subject: http://www.eyeonvision.org/
But I see it everywhere and probably far more pronounced than what is described in the article.
The article also suggests the phenomenon is temperature related, which I'd confirm. The times I've approached true panic for feeling "blind" have been between -20 and 30 degrees Fahrenheit, while I've always seen more of a mid to dark brown at warmer temperatures, from 50F up.
A toad's eye temperature can vary because it's cold-blooded. If humans' experience of eigengrau varies with outside temperature, well that's interesting and deserves study.
There is a video of Feynman presenting this lecture somewhere, sorry I couldn't find it.
While I cannot find the reference, some researchers recorded full visible-range spectrum for a very large number of naturally occurring objects. Then they performed principle components analysis of these spectra and found that for naturally occurring reflection spectra, nearly all signal energy is recovered with a small number of independent components like three or four. In other words, the spectra of naturally occurring materials does not vary as widely as it could to exercise the full Hilbert space available. A downside of having a larger number of cones is of course that the percentage area available to each cone will be less, so a higher density of cells would be needed to maintain the resolution and color perception under dark will suffer more. The nature then has chosen a near optimal number of cone types for vision.
One issue I had discovered with the above study was that it was possibly cyclic. The database of spectra they used did not had too many samples of (different) objects with the same apparent colors since the latter was collected primarily to count the number of human-distinguishable colors occurring naturally in nature.
If the number of primary colors visible to humans were significantly larger, I can on the very least say that TVs and printers would have been significantly different than what they are, if at all they would have been practical.
The above however does not answer the question of the electromagnetic radiation frequency span sensed by the eyes. In other words, why is the visible range not wider than what it is. Again, some animals do have a wider range. Had the visible range been wider, it may have required a larger number of primary colors to cover the expanded Hilbert space. What a physicist once told me is that the range of frequencies that are visible to humans and animals correlates very well to the frequency range under which water is transparent. See . This according to him offers a solid indication that life originated in water.
A few more interesting thoughts:
1. Figure out what determines the shape of the locus of the spectrum (monochromatic) colors on the color chart . It is an interesting exercise to derive this locus from the measurements of the spectral responses of the three cone types. Note that the outer boundary of the color chart has a straight line bottom with purple to magenta in the middle. While the non-straight boundaries span monochromatic colors, the colors on the straight edge at the bottom cannot be monochromatic. Figure out why.
2. A question comes if the spectral responses of the cones could have been such that the above locus would have concavities. I am not sure of the answer, though am sure colors outside of the locus but within its convex hull would still have been visible.
This provides some reminder that evolutionary pressure does not select for optimal coverage of the EM spectrum, but for the portion of the EM spectrum which will provide advantages.
> This according to him offers a solid indication that life originated in water.
Huh? Why assume that eye designs should have evolved underwater then remained unchanged for the hundreds of millions of years that life has been on land? Eyes have actually re-evolved independently several times (IIRC).
I always thought that it was related to the spectrum of sunlight.
It would be interesting to see some type of measure of the information content of adding more infrared in typical nature scenes.
I wonder what's going to be the next big innovation in filtering the firehose?
I suffer from epilepsy and often I see scintillating scotoma, visual snow and other strange light phenomena. Given this I came to the conclusion that my brain associate this color to a quiet mental state.
I observe that the intensity of the "Eigengrau" depends on how tightly I close my eyes. With the flashlight, the image is clearly more red than gray. This could explain some reports of "brown", to the extent that brown is a dark red.
If knowledge about our world is a pitfall, then I'm happy to seek out new traps.
I don't know why it's #1 though. Maybe pg's skewing the numbers against all the NSA content? Maybe people are just upvoting anything that's not NSA/Snowden/etc?