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Questions tagged [vision]

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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Can both lenses of different eyes intentionally focus at different amounts

Can each lens of both eyes have different accommodation rates, or have a different focal length to view objects of different distances. I understand that this can be a problem known as Anisometropia, ...
Astrovis's user avatar
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23 views

Why does Haidinger's brush tilt depending on rotation direction?

Based on the Wikipedia explanation of Haidinger's brush I would expect it to remain oriented to the light polarization, no matter which way I rotate my head. However that is not what I observe. When I ...
jpa's user avatar
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3 votes
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21 views

Is there a functional model of the human retina for simulation of conversion of illuminance pattern to nerve signals?

I'm looking for a model that would take a pattern of spectral irradiance over the retina as a function of time and space and convert this into the signals propagating through the fibers of the optic ...
Ruslan's user avatar
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2 answers
111 views

How do we see the violet color?

Here is exactly the same question with an accepted answer. However, that answer looks wrong (I can’t find the “alert moderators” button). Firstly, it refers to a dubious source. Secondly, it ...
Imyaf's user avatar
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2 votes
0 answers
64 views

Why do different people perceive the colors of the Northern Lights (Aurora Borealis) differently?

A few days ago, I was in Norway with a group of about 20 people. We were fortunate enough to witness an impressive display of the Northern Lights that lasted several hours. The next day, we discovered ...
Vorbis's user avatar
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How do you re-adjust gaze coordinates after bad eye tracking calibration using Matlab? [closed]

As a beginner with oculometric data pre-processing (in children from 2 to 12 years old), I would want some advice from the community! :) Using a Tobii Pro Fusion Eye tracker (250Hz), children are ...
Camille's user avatar
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15 views

Human Eye Diagram: question about some dimensions

Does anyone know any of the answers to these questions about this human eye diagram: What points should be the center of the circle for the radius numbers (Rn) in the following diagram? The ...
Nick's user avatar
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26 views

What can't the human eye see far-UV, X-rays, and gamma rays? [duplicate]

This is as much of a physics question as it is a biochemistry question. But how does rhodopsin(and the retinal chromophore itself) respond to ionizing radiation? Photons whose wavelength is longer ...
Mr X's user avatar
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38 views

how can a patient with conduction aphasia answer questions but not repeat words?

When we have a Q&A with someone, the path in the brain goes as such: auditory cortex to Wernicke's area (to be comprehended) which then activates the Broca's area to initiate a motor reaction (so ...
Maria's user avatar
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1 vote
1 answer
68 views

why do we use the glasses so that a different image is seen in each eye in the binocular rivalry experiment?

If we use the glasses so that in the right eye we see a house and on the left eye a face, we can see with a fMRI that the FFA is activated when seeing the face and the PPA activated when seeing the ...
Maria's user avatar
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How does retinal ganglion cell receptive field affect the LGN neuron activity?

If we have a spot of light hitting the center of the ON center receptive field of a retinal ganglion cell, will the LGN neuron be activated? Will the V1 neuron be activated? I mean its receptive field ...
Maria's user avatar
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2 votes
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how many bipolar cells connected to a ganglion cell?

Is it that only one bipolar cell is connected to one ganglion cell (which (ganglion cell) is connected to only one LGN neuron cell)? I mean if more than one bipolar cell is connected to a ganglion ...
Maria's user avatar
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1 vote
1 answer
66 views

what does concentric antagonistic areas in the retina mean?

"concentric antagonistic areas seen in retinal and LGN receptive fields." (Source: Neuroscience: Exploring the brain) So the receptive field of a ganglion cell is either ON or OFF center. ...
Maria's user avatar
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Does tetrachromacy affect eye color?

The majority of people have three cones in their eyes, though there are rare cases of some people having 4 cones (tetrachromacy). There is some genetic testing to support evidence of tetrachromacy, as ...
Nick Muterspaugh's user avatar
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0 answers
32 views

How do colorblind people see the back of their eyelids?

When people close their eyes, they still see and they see the back of the eyelids, in colorblind people, they see the back of their eyelids differently, how do colorblind people see the back of their ...
Amber Alvia's user avatar
2 votes
0 answers
28 views

How good is the vision of diurnal birds of prey really?

Diurnal raptors (especially eagles and hawks) are commonly thought to have incredible visual acuity, up to 5 or 8 times higher than a typical human. However, I haven't been able to find any scientific ...
Daniel Mazdak Honar's user avatar
3 votes
0 answers
75 views

Would using positive numbered glasses while using a computer help prevent myopia?

There are multiple web pages linking screen-time and myopia. While this is not necessarily proven, for example as shown on the NIH page here https://pubmed.ncbi.nlm.nih.gov/31943280/ , it seems ...
123's user avatar
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1 vote
0 answers
49 views

How does brain activity change when focusing on something within peripheral vision, as opposed to the fovea?

Normally when looking around, we mentally focus on what we see within our fovea, as that is where we have the greatest visual acuity. However, it is still possible to focus (both physically with the ...
M S's user avatar
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0 answers
20 views

Did animals primarily evolve to differentiate UV-rich sky from UV-poor substrate OR did they evolve to see visible light? [duplicate]

I read two things that appear to contradict each other. The reason humans only see light in the visible spectrum is likely related to the transmission of light waves through water: most infrared and ...
aquaporin's user avatar
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1 vote
1 answer
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Where does the notion that "a single eye has no depth perception" come from?

We've all heard that we have two eyes for depth perception, and if you only have one available, you have no depth perception. But this seems to be a false claim, one that can be trivially disproven ...
Mason Wheeler's user avatar
27 votes
3 answers
6k views

Did predators evolve eyes first?

I'm an engineer and biology is my weakest point, so please forgive if this question is dumb. Lately I've been wondering, "Why do animals that have eyes tend to have exactly 2 of them?" The ...
James Strieter's user avatar
1 vote
0 answers
39 views

Why do protanopes see yellow and not green?

Why can protanopes see yellow but not green when the relative absorbance of these two colour waves by the m cone can be identical?
sasha times's user avatar
0 votes
0 answers
32 views

Are afterimages centrally regulated?

As I understand, negative afterimages might be induced by retinal cone bleaching or neuronal adaptation. I have heard that some experiments have suggested that afterimages can be centrally regulated. ...
an instance's user avatar
2 votes
0 answers
26 views

What Type of Color Vision do Mantises have?

I am trying to figure out what type of color vision mantises have, but stuff about mantis shrimp keeps coming up instead. All I was able to find was this one paper from 1971. It found evidence that ...
E Tam's user avatar
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2 votes
2 answers
82 views

Is harmonic resonance in Photoreceptors explored?

Look at the resonance curves of the L-cone (OPN1LW) in humans, it has its peak at ~570nm and rises up in the lower wavelength (higher frequency) area. For me as a musician, that looks like a natural ...
rhavin's user avatar
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3 votes
1 answer
218 views

Can dogs see infrared radiation, i.e., heat?

I, like most of my fellows, prefer my meals served piping hot. As all know, humans sometimes feed their dogs table scraps. If I put down a small piece of chicken from within a piping hot chicken pot ...
the_fens's user avatar
0 votes
0 answers
33 views

Can color-blind people see the effect of combining red, green, and blue light beams?

When combined, red, green, and blue light beams result in white light. This effect is observed by most of us, but can color-blind people also see this effect?
Jordan G's user avatar
3 votes
1 answer
167 views

Why does there have to be two muscles to control the size of the pupil?

In dim light, the circular muscles relax and radial muscles contract to allow more light to enter the eye, and vice versa in bright light. Why is there the need to have two muscles when probably the ...
user1039203's user avatar
1 vote
0 answers
57 views

Confused About Why Red Queen Hypothesis Wouldn't Apply to Deer's Color Vision [duplicate]

In this site,https://www.livescience.com/why-are-tigers-orange, it says ""But there seems to be no evolutionary pressure, particularly for deer, which are the main prey of the tiger, to ...
MeltedStatementRecognizing's user avatar
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0 answers
30 views

Why do people say that blue light is damaging to the eyes?

It's easy to find claims that blue light (e.g., from computer screens) is damaging to the eyes. For example, here is some discussion of the topic. Is there any physical mechanism by which blue (not ...
Matt's user avatar
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5 votes
1 answer
150 views

Biological basis for the illusion of being pulled uphill on a *magnetic hill* when, in fact, one is coasting downhill?

A "gravity hill" is one where a downhill slope appears to be uphill, such that an object such as a car will appear to roll uphill when in fact it is moving downhill. This is described in a ...
anongoodnurse's user avatar
0 votes
0 answers
39 views

Optic Nerve: neurons/area and bit rate?

Does anyone know the number of neurons adjoining a cross sectional area of the optic nerve and the theoretical bit rate of the nerve? I read that the ON cross sectional radius is 3-5 mm and the ...
Nick's user avatar
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0 votes
0 answers
14 views

Vision System: neural activity is modulated using FSK?

I’m learning about the human vision system and signaling. Does anyone know if the signaling used by the vision system is modulated at the neuron using amplitude frequency shift keying? I present my ...
Nick's user avatar
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2 votes
1 answer
46 views

Vision and signal through the nervous system: Is it Frequency Shift Keying?

I have questions regarding the signal between the retina and other parts of the brain. There are two types bipolar cells which are excited by light or darkness to the retina. Question: Do these form ...
Nick's user avatar
  • 229
0 votes
1 answer
48 views

How does the brain activate retinal cones in darkness?

The activation of retinal cones by light is how vision is formed; yet there are other methods, such as mechanical one, for activating light, such as pressure photopsia/phosphenes. This occurs when ...
Evamentality's user avatar
0 votes
0 answers
26 views

Why do eyes feel exhausted after reading on a computer screen for a long time? [duplicate]

Similar question before closing this one was: Question. The answer holds true for most of the observations, but my observation differs from what is described in that question. Even if we consider that ...
lousycoder's user avatar
25 votes
2 answers
4k views

Why do blood vessels in the eye not obstruct vision?

As light enters the eye, it reaches the photoreceptors at the "base" of the retina, which then pass that signal to the bipolar and ganglionic neurons -- the latter of which send the signal ...
theforestecologist's user avatar
0 votes
2 answers
432 views

Are color-blind carriers partially colorblind?

Since color-blindness passes along an recessive gene in the X-chromosome, women are rarely affected, while men are affected more frequently. Women with one copy of the color-blindness gene are said to ...
Zo-Bro-23's user avatar
  • 581
7 votes
1 answer
1k views

Do color-blind people have more rod cells in their retinae than the normally sighted?

All types of color-blindness are said to be caused by the defect or lack of cone cells in the eyes[1]. Since cone cells sense color[2] and rod cells can only sense light intensity[3], the lack of cone ...
Zo-Bro-23's user avatar
  • 581
6 votes
1 answer
144 views

How is the extraordinary eyesight of some deep-sea creatures explained?

Mantis shrimp is a marine crustacean that is known to have a vision system that is much more complex than the eyes of many animals living on the ground. As explained here, it has 12 types of ...
Mostafa's user avatar
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7 votes
1 answer
1k views

What do cats see when they look at 2D, still images?

My cat doesn't like other cats. She doesn't really like anyone that isn't part of our family. So when she sees other cats she will aggressively try and chase them out of her area. She will also do the ...
etgriffiths's user avatar
1 vote
1 answer
42 views

How does slowed action potential propagation in the optic nerve cause blurred vision?

Multiple sclerosis is accompanied by optic neuritis, and there is demyelination of the optic nerve, causing the action potential to be propagated more slowly along axons. But how does this lead to ...
green onion's user avatar
0 votes
2 answers
193 views

Would green light look different if blue and red cones were deactivated

When looking at a graph plotting "blue", "green" and "red" cones reponses to different wavelengths, you can see that any wavelength trigerring a response from green cones ...
Uretki's user avatar
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1 vote
1 answer
209 views

Why do I see purple stripes when moving a small source of light (flashlight) quickly in a dark room?

I was playing with my phone's flashlight (white) in a dark room, Just moving it around quickly when I noticed that I could see thin stripes of purple in the same shape as my hand moved, they didn't ...
ADR's user avatar
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0 votes
0 answers
26 views

Permission for Figure Reuse

I was wondering how I can go about gaining permission for reuse of a figure in this post. I was hoping to reuse the image that is exemplifying the cross section of the retina. If anyone know please ...
Aedan Enriquez's user avatar
1 vote
0 answers
83 views

Do animals with very small eyes see microscopic objects?

I understand that many small creatures have very elementary eyes: they are not scaled-down versions of the human eye but as I understand it often just light-sensitive organs for detecting movement. ...
releseabe's user avatar
  • 335
2 votes
1 answer
62 views

Is chromatic aberration related to the spectral sensitivity of the human eye and can it cause "relative myopia" and "relative farsightedness"?

in the text below, the authors equate chromatic aberration and the spectral sensitivity of the human eye. Aren't these two very different phenomena though? They also propose a so-called "relative ...
Fipah's user avatar
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45 votes
3 answers
14k views

Are humans more adapted to "light mode" or "dark mode"?

I was discussing with a colleague about using dark-mode vs. light mode and remembered an article arguing that humans vision is more adapted to light-mode rather than dark-mode: I know that the trend “...
Alexei's user avatar
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1 vote
0 answers
57 views

Which animals can see (or feel) the Moon’s infrared radiation?

The luminosity (bolometric) of the Moon in infrared is several times greater that its luminosity in visible light. Moreover, it may be rather possible for the Moon to be obscured by some fog or haze ...
Incnis Mrsi's user avatar
2 votes
0 answers
43 views

Eye Optics/Emmert's law: Where to place scaled copies of an object so they have identical images on the retina?

I read that the center of projection of the human eye is the entrance pupil. So given a light ray which intersects the objects position and the center of the aperture stop, all copies of said object ...
InteractiveCube's user avatar

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