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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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
93 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 ...
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1answer
32 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 ...
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1answer
31 views

Myopia as a microscopic superpower?

A few years back my Physics professor made a joke that his Myopia/Nearsightedness gave him a "superpower" that allowed him to see close objects much more clearly than someone with typical eyesight. ...
13
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1answer
195 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
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1answer
70 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 ...
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1answer
61 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?
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1answer
97 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 ...
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1answer
37 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
146 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
81 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
130 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
47 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
1k 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 ...
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0answers
37 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 - ...
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2answers
115 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 ...
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2answers
183 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 ...
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1answer
90 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 ...
2
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0answers
37 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 ...
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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
198 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
466 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
1k 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 ...
6
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1answer
991 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 ...
2
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2answers
77 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 ...
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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?
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1answer
76 views

Can people with paralyzed eye muscles see?

As far as I am aware, the saccades of the eye are central to sight perception. If the eye is held still, the human stops seeing, even if light is reaching the retina and the visual pathway is intact. ...
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2answers
99 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
22 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
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2answers
125 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
58 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 ...
3
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0answers
31 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
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2answers
69 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 ...
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0answers
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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
57 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 ...
5
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1answer
111 views

Do blind people learn Braille equally fast as the sighted?

The visually deprived brain undergoes extensive remodeling due to cross-modal plasticity. This leads to increased areas of the cortex being available for other purposes such as tactile processing. Now ...
9
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1answer
88 views

Is our color vision calibrated to sky, vegetation, and blood?

Our color vision is based on three types of receptors (cones) which are sensitive to three distinct locations on the spectrum: 420–440 nm, 534–555 nm, and 564–580 nm. We label them "red", "green", ...
3
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1answer
133 views

Why do small fonts strain the eyes?

I understand that too much close reading will strain the ciliary muscles of the eyes. But what about small fonts? The contraction of the ciliary muscles is dependent on the distance not font size. In ...
7
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1answer
103 views

Can rapid eye blinking induce epileptic seizures?

Photosensitive epilepsies are characterized by visually-induced seizures. Flashing-light stimuli are known to induce seizures in some (but not all) patients. My question is whether people with this ...
0
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0answers
90 views

Does our brain really “flip” images perceived by our eyes? [duplicate]

I know a similar question has been asked and this is closely related to cognitive science. However, I want to know whether is there any mechanism or structure in the visual cortex which is proved to ...
3
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1answer
62 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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2answers
125 views

How does the eye know whether to focus further out or nearer in order to bring a blurry object into focus?

If the eye sees an object, but the object is out of focus, the eye could be focusing too near or too far. How does the eye (or the brain) distinguish one situation from the other? How does it know ...
2
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1answer
48 views

Like size and colour constancy, why does the brain not maintain focus constancy?

I have progressive myopia. I grew up with perfectly normal eyes but slowly started getting myopic. The thing is, my brain knows (or should know) what the world looks like -- it knows that far away ...
3
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1answer
41 views

What are limitations on the number of objects the eye determine at a glance?

Take two people Sam (average human) and Jack. Jack says to Sam "I'm going to show you some skittles (or other object) and I want you to tell me as quick as you can how many I'm holding." He opens ...
4
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2answers
97 views

Can the human eye distinguish colors in the periphery?

In the back of my mind I have the idea that human eyes can't notice the color of objects in the far periphery, and that any subjective perception of colors is done by the brain that tries to fill in ...
6
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4answers
301 views

Is human vision sensitive to frequency or wavelength?

In a vacuum, there is a one-to-one correspondence between light frequency ($\nu$) and wavelength ($\lambda$), ie. $\lambda=c/\nu$. But in a refractive medium, $\lambda=v/\nu$, so while the frequency ...
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2answers
15k views

What is it called when one human eye is seeing brighter color than the other?

What is the name of a phenomenon where one of the human eyes is seeing brighter/more saturated color than the other? I can observe the same object from the same position while alternating which eye is ...
10
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2answers
504 views

If human eyes watch an area, what's the shape of its capturing shape? Rectangular? Half spherical?

A normal camera can capture a rectangular image. If human eyes watch an area, what's the shape of the captured region? Rectangular? Half-spherical?
10
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1answer
320 views

What are the “stars” we see after a bump on the head?

Sorry if this might appear funny. When I close my eyes for a longer time, and suddenly open it, I see some twinkling white small circles, and when i concentrate on anyone of them it disappears, as ...