Talk:Photoreceptor cell/July 2006 talk

Merge

I have suggested that Photoreceptor be merged here; it's an essentially identical article. Photoreceptor is also a little repetitive, and I'd like to trim some of the info that's mentioned multiple times. Any objections to either of these suggestions? delldot | talk 21:11, 20 February 2006 (UTC)

The photoreceptor article is quite long as it is, if the photoreceptor article and photoreceptor cell articles were merged it could become very long. It's down to personal opinion in the end but I thought it was worth mentioning.—The preceding unsigned comment was added by 86.139.27.253 (talk • contribs) 11:45, 4 March 2006 (UTC).

There obviously needs to be some merging of information regarding retinal photoreceptors, however, I'm not sure whether there should be a merge or which way that merge should go. There are photoreceptors that are not cells (i.e. varous types of light-detecting machines), and their are photoreceptor cells that are not neurons (i.e. again, various types of light-sensors). -AED 06:13, 19 June 2006 (UTC)

Why not do the merge the other way? Isn't photoreceptor a simpler title than photoreceptor cell? What's the difference? -Silence 18:40, 21 June 2006 (UTC)

Photoreceptor cell is more specific. As noted above, there are "photoreceptors" that are not cells, and which are not covered by this article. A photodiode could be considered a "photoreceptor", for example. I'm OK with merging to photoreceptor, if others feel that is preferable. I think merging to the longer term may be clearer.--Srleffler 23:02, 26 June 2006 (UTC)

I'm OK with that. Do you think it would be wise to then make Photoreceptor a disamb page that would list Photoreceptor cell and Photodetector/Photodiode. -AED 23:18, 26 June 2006 (UTC)

• I realize that "photoreceptor cell" may be clearer than just "photoreceptor", but I'm unconvinced that "photoreceptor cell" is significantly more common in referring to these cells than just "photoreceptor". Commonness is what really matters: we don't need to explicate exactly what an article is about in the title; that's what the first sentence is about. It's better, in general, to have a simple and common title than one that makes absolutely sure that readers know the subject beforehand (e.g. George W. Bush is better than President George W. Bush, Human is better than Human being, Earth is better than Planet Earth, etc.). The main evidence I see that "photoreceptor cell" is more common is Category:Photoreceptor cells, but that could have arisen as a result of this page; the main evidence I see that "photoreceptor" would be preferable, on the other hand, is this article's parent article: Receptor cell redirects to Receptor (biochemistry)! That, in itself, makes me seriously question which way this merge should go. If we end up merging this page to "photoreceptor", we could easily add a dab notice to the top of that page linking to photodetector, etc.; what matters is figuring out the most common and accurate title. (Only if "photodetector" is very commonly used to refer to things other than photoreceptor cells should be necessarily consider making "photoreceptor" a dab page: if we end up making the page "photoreceptor cell", we should probably just redirect "photoreceptor" here and, if necessary, put the aforementioned dab notice at the top of that page. It depends on how likely it is that people would look for photoreceptor cells, or for something else, when they search for "photoreceptor".) -Silence 00:05, 27 June 2006 (UTC)
  • You have a good point. "Photoreceptor" is probably pretty rarely used to refer to non-biological sensors. I would be fine with merging to the simpler title, if others agree.--Srleffler 04:21, 27 June 2006 (UTC)

• I'm OK with that, too. -AED 04:44, 27 June 2006 (UTC)

If anyone is still following this page, please note that I've proposed moving the article back to "Photoreceptor cell" and replacing it with a disambiguation page for reasons explained at Talk:Photoreceptor#Requested_move. Please feel free to comment. - tameeria 21:10, 17 March 2007 (UTC)

Disputed section

I have moved the disputed section here, for discussion: Srleffler 22:44, 26 June 2006 (UTC)

Rods and Cones

Each of your eyes has over three million photoreceptors called rods and cones. These receptors convert light into electro-chemical signals that travel through the optic nerve and into the brain. Here, these signals trigger the neurological process called photosensitivity. The rods in your eyes specialize in night vision, and can function at much lower light levels than cones. However, they do not respond to color. This is why we can only see in black and white when we are in the dark. The cones in your eyes, on the other hand, specialize in color and come in three types: those that respond to the color red, those that respond to the color green, and those that respond to the color blue. All of the colors that we experience are the result of these three types of cones firing off in different combinations. When you look at something, the rods and cones in your eyes fire in rapid succession. But, between each firing, there is a brief resetting period, during which, your eyes are unable to take in any new information. Your brain covers up these microscopic moments of blindness with lingering after-images which help make your vision appear to be fluid and uninterrupted, even though it is not. This phenomenon, known as persistence of vision is the unique physio-logical quirk that makes the illusion of animation possible. The dark spaces between each still frame of animation literally sneak by while your eyes are not looking.

Problems with this section

1. Parts of it are written in the second person, contrary to the Manual of Style.
2. The number of rods and cones cited is wrong or at least misleading, and the correct number already appears in the article. One hundred and thirty one million is a lot different from "over three million".
3. The three types of cone cells are not specialized for red, green, and blue. See Cone cell. The peak responses for the three types are, respectively, to yellowish-green (564 nm), bluish-green (534 nm), and blue-violet (420 nm). The color processing done in the eye and brain is quite complex. It's not as simple as RGB color television. :)
4. Not all animation has a dark space between frames. That was true of old movie projectors, but is not true of television, for example. I tried to replace this with an example based on fluorescent lighting, but 216.15.73.245 seems not to have found this acceptable.
5. I am doubtful about the claim that there is a "resetting period" during which your eyes are unable to take in information. This claim at least needs a reference to support it. I would believe a claim that each rod or cone has a "resetting period" after it fires, but I doubt that the entire eye is "blind" all at once.
6. The original version of this section contained a version of Image:Grid illusion.png (although with a different filename), and claimed that the illusion of moving black dots was caused by persistence of vision. This is certainly not clear, and perhaps quite doubtful. This type of illusion is discussed in the article Grid illusion, and from the information there it does not seem that persistence of vision comes into it. At least, a reference would be needed to put forward this claim in a Wikipedia article.
7. The section contains information which is redundant with the rest of the article. It's as if the author just slammed it in here, without bothering to even read the rest of the article.
8. I'm not sure photosensitivity is the correct term for the neurological process here. At least, the linked article seems inappropriate in this context.

I tried editing the section down into a paragraph about persistance of vision, which fixed these problems. The anonymous author of this section simply reverted the edits, twice. I have moved the section here for discussion in the hope that we can resolve this and come up with a reasonable compromise text that is factually correct and has the correct encyclopedic tone.--Srleffler 22:44, 26 June 2006 (UTC)