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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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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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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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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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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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 ...
Raquel Alvia's user avatar
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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
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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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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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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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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
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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
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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
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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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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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Why does grey-blue look violet?

The top right corner of this color picker is RGB(0, 0, 255). However we can see a slight violet tint, in the light-blue, blue-gray areas. The top right corner of this color picker is RGB(0, 60, 255). ...
AzulShiva's user avatar
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3 votes
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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
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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
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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
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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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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
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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
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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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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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Vision and signal through the nervous system? [closed]

I have questions regarding the signal path between the retina and other parts of the brain. An understanding and then questions in bold follow. Wikipedia states: Retinal ganglion cells spontaneously ...
Nick's user avatar
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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
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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
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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
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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
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7 votes
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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
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6 votes
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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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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
38 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
120 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
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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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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
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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
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2 votes
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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
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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
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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
3 votes
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Understanding David Chalmers claims on direct mappings between our vision and visual awareness systems

I am reading the popular 1995 paper "Facing Up to the Problem of Consciousness" by David Chalmers [PDF] as part of my philosophy course. I am only asking about the relevant vision related ...
Gaurang Tandon's user avatar
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1 answer
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Term for a prey animal's recognition that something potentially threatening is looking at it?

On my daily walks I frequently see individual or small groups of cattle egrets. At first I would try to photograph them but they would fly away. This vexed me because they ignored everyone else ...
uhoh's user avatar
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How much percent of image does our eyes focus at any instant?

I learned in highschool that even thought we have a wide view, we only observe a tiny fraction of that view through our eyes. So at any instant we are not really looking at all the objects infront of ...
gfdsal's user avatar
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2 votes
1 answer
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Why does our visible range not include infrared or UV radiation? [duplicate]

As the radiation peak of the sun is in the UV region and since at around room temperature materials emit radiation at IR, I wonder why our eyes are not capable of using these wavelengths. I guess ...
Ben's user avatar
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Why do we get tunnel vision during fight or flight response?

I have a question regarding tunnel vision during the fight or flight response. I believe that during fight or flight high levels of adrenaline are released which causes the pupils to dilate allowing ...
James's user avatar
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Why do we have both on and off bipolar cells?

I have a question regarding the reason behind the 2 bipolar cells. So, from my understanding we have both on and off bipolar cells and from the numerous diagrams I have seen, I find that most show a ...
James's user avatar
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1 vote
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Why does Cyan appear bluish rather than greenish, when the phototopic eye sensitivity is highest in green (and Cyan contains blue and green equally)?

Cyan contains blue and green equally. Phototopic eye sensitivity is highest in green. Why, then, does Cyan appear bluish to most of us, rather than greenish?
Ritesh Singh's user avatar

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