Questions regarding how the brain interprets information from the eyes. Consider using the "eyes" tag for discussion of eye anatomy, physiology and evolution.

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1answer
33 views

What is the relationship between W, X, Y and P, M retinal ganglion cells?

In Guyton and Hall Textbook of Medical Physiology (12e) the retinal ganglion cells are classified into W, X, and Y types. However in Gray's Anatomy (40e) they are classified into Midget and Parasol ...
2
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1answer
81 views

What are dreams, biologically?

Falling asleep or states of subconsciousness does not stop the mind from making its own fictional images. These seem like sensations just like those received from human eyes. But, how do we define ...
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5answers
105 views

Why is human vision restricted to 400-700 nm?

Across the electromagnetic spectrum, 400-700 nm is a narrow spectrum of frequencies and focused in the region of short wavelengths. For example, radio waves cover a large range of frequencies ...
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0answers
22 views

Undistorting peripheral vision

I am interested in a procedure which can be applied to an image (or video) which is situated in my peripheral vision, and will result in an undistorted copy being presented to my brain. I do not know ...
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2answers
40 views

Can a woman possessing 1 mutated allele show attenuated color-vision deficiency?

Women possess two X chromosomes. However, during development, when the embryo has about 32 - 64 cells, one of these chromosomes is randomly inactivated (in each cell) by an lncRNA named Xist. As a ...
8
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1answer
399 views

Reason for seeing grid-like patterns when strobing a solid black-white image?

I was trying to do some stimulation for SSVEPs by strobing a solid black square and a solid white square. Weird thing was, I ended up seeing weird grid like patterns that looked like this, always of ...
3
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2answers
69 views

Myopia as a microscopic superpower?

A few years back my Physics professor made a joke that his myopia (i.e., nearsightedness) gave him a "superpower" that allowed him to see close objects much more clearly than someone with typical ...
9
votes
1answer
119 views

Can people with paralyzed eye muscles see?

As far as I am aware, the saccades of the eye are central to visual perception. If the eye is held still, the human stops seeing, even if light is reaching the retina and the visual pathway is intact. ...
4
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2answers
131 views

Do animals exist which have great vision, but see only grayscale?

In computer vision the color information is often discarded, as most object recognition tasks seem to work just as well on the greyscale image (even better, because there is less unnecessary ...
8
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1answer
72 views

What processes are responsible for focusing on an image only seen by one of the eyes?

When a person is spying from around a corner with only one eye, it's rather easy to ignore the other eye's image, since it's probably much darker, because one usually spies around a corner standing ...
6
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1answer
61 views

How does the frequency of a visual stimulus affect the steady-state visually evoked potential?

I want to design a project for EEG signal processing. In my research I found the concept of SSVEP. SSVEPs represent the electrical activity of the brain as measured via EEG, and are evoked by visual ...
5
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1answer
86 views

Effect of closed eyes on balance?

Suppose you want to stand on one leg. Doing it eyes open is not that difficult, but doing it eyes closed seems to be difficult. Why?
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1answer
709 views

What portion of the electromagnetic spectrum do cats see?

I have seen numerous articles and various information about how cats and dogs see into the ultraviolet spectrum with interesting artistic renderings such as this: ...
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0answers
32 views

Why are there ghost images of objects just out of focus

I have observed an interesting phenomena with my vision lately. I just think I have never reflected over this before but it might always have been this way. I am nearsighted and have no problem with ...
2
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1answer
28 views

How does myopia actually work?

This is potentially more or less a question about optics, but I've never been truly satisfied with any explanation that I've been given about Myopia. In fact, I almost can't even believe it. There are ...
8
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4answers
2k views

What is the difference between a circular and a cat's-eye pupil?

I've been to local zoo the other day and one lizard caught my attention: its pupils are circular, which, I thought, is not usual for reptiles. Turns out it is, but now I can't find any explanation on ...
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0answers
38 views

What are those visual and auditory reflex controlled by the midbrain? [closed]

The midbrain is a centre for certain visual and auditory reflexes. But what are those reflexes exactly? My study book says that these reflexes are, e.g., responsible for moving the eyes to view ...
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2answers
58 views

Why is my peripheral vision better for seeing in the dark? [duplicate]

I often walk around my house at night with the lights turned off and one night I noticed that looking straight at an object with very little light available made the object disappear from sight but if ...
6
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1answer
94 views

How well do we notice asynchronicity?

I'm stopped at a stoplight and, with nothing to do, my thoughts wander to the timed don't-walk sign that governs any pedestrians who might wish to cross the street I'm driving along. I can see two ...
8
votes
1answer
75 views

Why can I see a light flicker when it's in my peripheral vision?

When I'm looking at an old CRT monitor or a worn fluorescent lamp, but not directly in the center of my gaze, the light from it seems to flicker. When I focus my gaze onto the monitor or lamp, the ...
14
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1answer
220 views

Effect of pupil responses on the electroretinogram

The electroretinogram (ERG) is generally considered to reflect the retinal processing of a light stimulus, typically a photoreceptor response followed by secondary neuronal activity. I am wondering ...
5
votes
1answer
76 views

Are some facial features more important than others in human facial recognition?

I'm often surprised by the human ability to correctly identify other individuals despite significant modifications due to ageing, hairstyle, injury, etc. But, sometimes the addition of a beard and a ...
4
votes
1answer
69 views

Can other animals see black differently?

I am not sure if this is the right place for this question, but this is a debate that has been going on between two colleagues for days and I need a resolution because it's driving me crazy. So any ...
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6answers
3k views

What is the use of eye banks, if eyeball transplants do not exist at present?

Corneas are donated and transplanted, but not the eyeball. I don't understand. What is the purpose of donating a cornea without an eyeball to a blind person?
5
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1answer
100 views

Congenital blindness due to retinitis pigmentosa - does it exist?

Retinitis pigmentosa (RP) patients typically become blind after a period of years in which their eye sight slowly deteriorates due to photoreceptor degeneration. Generally RP patients develop ...
2
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1answer
58 views

What is the difference between myopia and hyperopia?

In myopia the lens is bending the light too much even in the most relaxed state. Thus the image is produced in front of the retina. If the object comes closer the lens just adjusts a bit less than a ...
6
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1answer
153 views

How is color information transmitted from the eye to the brain?

Is color information sent from the eye to the brain frequency-modulated, or are different colors transmitted by different axons? I know that each ganglion cell is connected to multiple ...
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2answers
148 views

Why can't the human eye focus blue light?

I recently noticed that it is hard to focus on blue light sources, especially at night. When observing a blue light source, e.g. a neon sign, it looks somewhat blurry. A sign with a different colour ...
6
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2answers
143 views

Advantage of opponent color?

Opponent process is a color theory that states that the human visual system interprets information about color by processing signals from cones and rods in an antagonistic manner (source). What is ...
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0answers
50 views

Why does a human's field of view narrow when moving faster?

A relative of mine is a driving instructor and he regularly likes to bring up that the field of view narrows noticeably when driving at higher speeds. Is this true, why is this so and does this apply ...
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4answers
2k views

Why did life not evolve to use radio?

We use electromagnetic communication everywhere these days. Cell phones, wifi, old-school radio transmissions, television, deep space communication, etc. I'm curious about some of the possible ...
2
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0answers
47 views

How do parrots stabilize their field of view without moving their necks while walking?

Based on my search online, I have found some theories which try to validate the activity of some birds (like pigeons) which involves moving their heads and neck while walking. These theories include - ...
4
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2answers
154 views

How does optogenetics work?

I am aware of the post here 'Optogenetics - How do microbial opsins work?' however it is a bit too technical for me. I am struggling to understand how the neurons can be genetically engineered to ...
2
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2answers
191 views

What is the minimum eye?

What is the minimum eye which confers some evolutionary advantage? By minimum I mean anything less than this has no advantage whatsoever and therefore is not favored by natural selection. By eye, I ...
3
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1answer
103 views

Retina Transplant Difficulties

Why is retina transplant not as easy as the normal eye donation and transplant (I think the latter involves the cornea ) ? This says that a new method has come up but why isnt the process similar and ...
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0answers
48 views

Sensitivity of eyes to flashing lights

My eyes are very sensitive to flashing lights - for example I'm always the first person to notice that a fluorescent tube is about to fail because I see it flickering when other people can't. When ...
12
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3answers
3k views

Superhuman eyesight

My ten year old son was reading car number plates that were too fast, too far away and at the wrong angle for any of us to read or even believe that it was possible for him to read. We thought he was ...
3
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1answer
211 views

Perception of distant lights without glasses

I am fairly short-sighted and wear glasses pretty much all the time. Naively, I would expect that when I take my glasses off, the image I see should look very much the same as as a photograph that's ...
6
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1answer
577 views

Why does a light object appear lighter in your peripheral vision when it's dark?

So, I am not sure I can reproduce it via images, but the steps are: 1) At night, open a window and have a look at the surface of the earth 2) Suppose there's an object that reflects a tiny amount of ...
5
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2answers
2k views

Does coloring affect the perception of depth?

I have a question about the mechanics of human vision which may be as much of a physics question as it is a biology/physiology question. I noticed that if I try to imagine a clear blue daytime sky ...
7
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1answer
2k views

What is the field of view for the human eyes?

I'd like to know how much a person can see regarding the angles. If it is a rectangle, I'd like to know it's height and width. But if is another shape, I'd like to know which kind of shape and the ...
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4answers
3k views

Why can cones detect color but rods can't?

I don't know if this question applies to only humans but why can cones see much greater detail than rods? Is it possible to have a rod that can detect light intensity and color?
2
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2answers
103 views

Parallels between pixelized image and the human retina

On Wikipedia it is explained that the human eye has a certain 'resolution'. Does this mean that the retinal image consists of pixels? If yes, what shape would these pixels have?
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0answers
23 views

Why after physical activity I see flickering concentric circles? [duplicate]

After prolonged hard physical exercise such as running uphill I sometimes experience rapidly vibrating black-and-white concentric circles for a few minutes, looking like a sinusoidal zone plate, small ...
4
votes
2answers
164 views

Why don't myopic people see the world upside-down?

I found this image while reading optical instruments in physics. If we look at the uncorrected rays, we see that the image they outline gets inverted. So why don't people with myopic vision see ...
2
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1answer
68 views

Using perceptual adaptation for enhancing realism of VR/other entertainment

I am quite a fan of the recent oculus rift VR glasses, but it does have several flaws over normal vision, most notably a much less wide field of view, the so-called screen door effect because of too ...
4
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0answers
45 views

How far can birds see? [closed]

I have heard that birds have exceptional eyesight. How far does this mean they can see? What's the resolution like? Are we talking about just vague shapes or something like, at 100 feet, seeing ...
7
votes
2answers
78 views

Can the eye distinguish between pure and composite colours and how do we measure this?

Red light plus green light makes yellow light. Suppose I shone a pure red light, say 650nm, onto the same spot as a pure green light, say 550nm. The eye sees this two-peak spectrum as yellow. This ...
3
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0answers
29 views

Color perception vs shade perception demo

I can't seem to find one of the best demos I've seen of color vs brightness perception. It consisted of a rotating animation of earth made of red of bright red points on a dark green background. As ...
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1answer
66 views

Does pupil size affect image focus in persons with no lens?

If an individual has no lens like Claude Monet (who had them removed). They should be able to still focus the images they see in a well light area if they shrink their pupils to a very small size ...