Rethinking the Process of Vision

We all see red as red because the physical diameter of the large (cone) receptors  on our retinas are the same size.

As explained in this work,  the diameter of our large receptors (which have traditionally been termed cones)  determine the long light wavelength limit of our vision.  This diameter sets the center-to-center distance between receptors and, in antenna terms, “tunes” the light detection center  to this primary wavelength while at the same time setting the long light wavelength limit of visual response. When  a simple geometric principle  is applied (see my Rosetta Stone diagram)  the basis for the three primary light wavelengths of vision becomes  obvious.

Note that these primaries are simply narrow light wavelengths and are not yet the hues of color.

The term color should be reserved for the many hues that are synthesized by the eye from the three primary wavelengths, using the scheme brilliantly discerned without any of this knowledge, by Edwin Land.

In this geometric scheme the exact center of the visual band (i.e., 550 nanometers or green) is geometrically determined on the retina.  This exact center is used as a central wavelength reference point from which all of the hues of color are subsequently  synthesized  by the eye. This is the fulcrum described by Land which forms the basis for the well known but never explained visual characteristic of color constancy.  Again, we owe this  initial insight to the work of Edwin Land.

Thus we humans all identify the same primary light wavelengths because we all have retinal receptors of approximately the same diameters. Our discernment of color is the result of a simple geometric principle.

These diameters are approximately the dimensions of light wavelength or, in physics terms, in the near field of light. The retina is composed of ~150 million individual light detection sites of these dimensions that operate (switch?) in the realm of femtoseconds (10-15 sec).  This implies that the eye interrogates the domain of quantum physics and that these physics must be considered in ultimately  understanding  the process of vision.

I must here restate the basic rules defining retinal response to light:

1.  The absolute diameter of a receptor determines  the light wavelength absorbed or emitted at that site by setting the center-to-center dimension between adjacent receptors.

Species of fish  known to have vision in the near infrared should  according to these rules have larger receptors than the human variety. Insects having vision in the near ultraviolet short wavelength region should have receptors smaller than human. The literature shows this to be true as I have referenced in the body of this work.  The cones of trout species  have a diameter of seven microns – seven times larger than humans.

2.  The discernment of color by any species requires that an admixture of receptors of two diameters be present on the retina.  The ratio of these two diameters will define the visible band for that species.

The ratio of the two sizes of human receptors (again, traditionally termed cones and rods) is 1.8:1, with this ratio corresponding  to the 700-400 nanometer bandwidth of human visual response.

3.  The  diameter of the  larger receptor will determine, within the bounds of antenna theory, the precise limit of  visual response to longer light wavelengths (~ 700 nm in humans). Analogously, the  diameter of the smaller receptor will determine the precise short wavelength limit of  visual response.

______________________________________________________

The simplicity of the above explanation of the vision process leads me to comment on a bit of text recently brought to my attention.  I was directed to a Wiki site that addresses the subject of color vision. In itself this site is of little importance but it does represent the anything-original-or -new -must-be-bad thought process characteristic in the vision science (and other areas of science) community.

Some text abstracted from this link (emphasis in all cases is mine):

“Is there any place in this article for an alternative theory, ie Gerald Huth’s website?

No. That site doesn’t make any sense.  22:03, 21 Mar 2005

I’ve read this site in some detail. At this time the idea is far too experimental to be considered informational. I am also of the opinion that this theory is easily refuted by a simple examination of the optical and mechanical properties of the eye, which are trivially measured and AFAIK do not agree with the degree of chromatic abberation required for this theory to work. Furthermore, the mathematics of waveguide effects around cone cells have been analyzed by others corrections to photopigment optical density have been estimated to account for the effect, and the author’s often-cited “mysterious” effects of induced-color perception experiments by Edwin Land are easily explained by modern color appearance models. Its fun to think that 300 years of vision science is completely wrong, but it does not appear to be the case. :)  08:12, 20 March 2007

My comments on specific points from the text:

“ the idea is far too experimental…” I would propose that any high school science student with a modicum of curiosity would understand this idea.  This is not a theory – it explains in the simplest of terms the historic results obtained in vision science.  I note, for example, the experimental results in the field of vision of Nobelist George Wald.

“….refuted by a simple examination of the optical and mechanical properties of the eye…” A simple simulation (using Light Tools optical simulation software, for example) using dimensions, index of refraction values for the various structures of the eye show immediately that light wavelengths are directed to the retinal eccentricities geometrically calculated in this work. I  had occasion to visit an investigator who was doing a much more precise simulation (for LASIC application as I remember) where, in a dramatic moment where he touched a key on his computer and brought up on the screen his simulation, the 550 nm mid band (green) wavelength was refracted precisely to eight degrees of retina eccentricity exactly as I had predicted.  I even recall his comment after listening to my explanation that “he would have to unlearn everything he had ever learned about vision if he were to believe me”..

“….waveguide effects around cone cells have been analyzed by others..” (underlining is mine). I do not believe that the writer meant exactly “around” – but if he did he would have been on the right track.  I have noted in the body of this work (referenced) the extensive efforts by Snyder, Enoch and others who theoretically analyzed individual receptors as light conducting (“iber optic) waveguides.   Parenthetically, I have noted that such treatment assumes the wave character of light – not photons interacting with pigments – oops!, the wave/particle dilemma again!

This author of the above comment ought to become aware of new results in contemporary physics.  A truly significant result by Boston University investigators (referenced in the body of the work) demonstrates that when the diameter of a fiber optic light guide is reduced to sub-optical wavelength dimensions (less than one micron – the dimension of retinal receptors) light is transmitted around and not through the guide.  The smaller the diameter the more light is shifted outside of the body of the fiber.  This is in exact accord with my explanation.

“….mysterious effects of induced-color perception experiments by Edwin Land…” Words almost fail me here as I have written so much on this subject.  If anything, the experiments and thoughts of Edwin Land are the most original, lucid and transparent thoughts that anyone will find in the field of science.  I like to compare Land’s writings to those of a great physicist, David Bohm, who thought and wrote with the same clarity.

I will recount again – some time ago an individual from a prestigious vision research group wrote to me concerning my interest in Land’s work.  His comment: (in his terms, speaking for the vision community) “we put Land’s work to bed years ago” referring me to a paper that would “clear things up for me”.  This is of such importance that I will here include that reference.  The title fascinated me and I dutifully obtained the reference (published in a journal that seemed obscure to me in relation to vision science). This paper can only be characterized as the screed of a very angry man filled with ad hominem attacks on Land (as, for example, characterizing him as an “inventor” - read “not a scientist”).  I would certainly never consider this an objective technical paper or any refutation of Land’s work!

The reference: “LAND! LAND!, by Gordon L. Walls, Psychological Bulletin, Vol. 57, No.1, 1960.

“…..300 years of vision science is completely wrong…” No, not completely wrong.  The trichromicity of the vision process was correct.  Beyond that, I have always felt since reaching this understanding that subsequent effort in vision assumed the wrong model and has attempted for many long years to stuff all experimental data obtained into that wrong model where it did not fit. Again, George Wald’s results are a major case in point.

In summary, a great deal of this is such utter foolishness! I have never wanted to believe Max Planck’s famous quote that “science advances funeral by funeral” but this may in fact be the case. Planck made this statement probably a hundred years ago – apparently things never change!

GCH

12.02.08

___________________________-

This entry was posted on Tuesday, December 2nd, 2008 at 12:06 pm and is filed under Running Commentary . You can follow any responses to this entry through the RSS 2.0 feed. You can leave a comment, or trackback from your own site.