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.
57
questions
16
votes
2
answers
773
views
Seeing strange things in light
I have noticed that if you look directly at tubelight (I have only white ones in my home) and close your eyes little, you see little random shaped colourless things sometimes with slow speed and ...
- 279
14
votes
2
answers
620
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", ...
- 525
12
votes
1
answer
406
views
What really is color and how do we perceive it?
How do our brains actually transform the information that the cones in our eyes receive into the different colors that we can see and imagine?
- 251
4
votes
1
answer
924
views
What is the biological potential for vision of wavelengths outside the human visual range?
Humans eyes have evolved to perceive light only between approximately 350-700nm, because that form of light is most common to our lifes. Other animals can perceive lights with slightly different ...
- 143
20
votes
6
answers
24k
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 ...
- 319
14
votes
3
answers
2k
views
How do we know the brain flips images projected on the retina back around?
Why do we turn images upside down again rather than dealing with them directly, still vertically rotated after passing through our lens?
I don't see how that would cause any problems, and how we'd ...
- 243
9
votes
1
answer
6k
views
What gives things their colour?
My 6 year old daughter asked me 2 biology-related questions yesterday and I tried my best to answer them with the aid of YouTube videos. One of the questions (I may post the other one too) was
How ...
- 275
71
votes
2
answers
26k
views
What is the evolutionary advantage of red-green color blindness?
Red-green colorblindness seems to make it harder for a hunter-gatherer to see whether a fruit is ripe and thus worth picking.
Is there a reason why selection hasn't completely removed red-green ...
- 2,606
15
votes
2
answers
1k
views
Are some animals, like dogs and cats, color-blind and how do we know that?
I have heard that some animals, including dogs, cats and donkeys, are color-blind. They cannot recognize any color. Is that true? And how can humans verify that animals are color-blind, or not? During ...
- 257
13
votes
2
answers
5k
views
Can "red" cone cells actually see much red light?
In electronics, the most common color scheme is the "red-green-blue" (RGB) scheme. This choice is often justified by claiming that the long- (L), medium- (M), and short- (S) type cones in the human ...
- 717
12
votes
2
answers
660
views
Is mammalian vision processed as a sequence of frames?
I often read that people believe that human vision has an inherent frames-per-second rate (FPS) that causes stroboscopic effects - such as seeing the spokes of a rotating wheel apparently rotating at ...
- 243
10
votes
1
answer
7k
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 ...
- 195
29
votes
2
answers
9k
views
Is it possible that by mutation a human could see infrared or other 'colours'?
Incoming light reacts with the several types of cone cells in the eye. In humans, there are three types of cones sensitive to three different spectra, resulting in trichromatic color vision. Each ...
- 2,765
15
votes
1
answer
1k
views
Is it a limitation of the eyes, or the brain, that we can't see a moving bullet?
Are the photoreceptors in our eyes not fast enough to register the fast moving bullet, or is the brain not powerful enough to make sense of something happening that fast?
- 971
15
votes
5
answers
13k
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?
- 4,509
11
votes
1
answer
9k
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 ...
- 249
8
votes
3
answers
6k
views
Are there animal species that sense infrared light with their eyes?
I asked a question earlier today about birds with infrared vision but this time I am asking about animals in general. I know that many snakes have receptors between their eyes and their snout that ...
- 245
8
votes
3
answers
2k
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 ...
6
votes
2
answers
15k
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 ...
- 2,606
6
votes
3
answers
18k
views
What is the equivalent of shutter-speed in Human eye?
I just learned that in video cameras, every frame of the video has its own shutter speed.
And I know how frame-rate in human eye works out, well, not completely, hence the question.
http://en....
- 971
4
votes
1
answer
316
views
Why is peripheral vision not bleached by daylight?
In daylight, rods are known to be bleached: we have to wait some time after going into darkness before scotopic vision becomes effective. But, as I understand, peripheral vision is also mostly due to ...
- 425
4
votes
1
answer
751
views
If people with colorblindness lack one type of cone cells, shouldn't they be unable to recognize one particular color?
The 3 types of cone cells in normal humans allow them to view 3 types of colors and any color made from mixing and matching those 3.
So, 2 types of cone cells should only allow to view just 2 types ...
- 971
3
votes
2
answers
318
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 ...
- 186
0
votes
2
answers
417
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 ...
- 581
83
votes
3
answers
15k
views
Is there an RGB equivalent for smells?
Millions of colors in the visible spectrum can be generated by mixing red, green and blue - the RGB color system. Is there a basic set of smells that, when mixed, can yield all, or nearly all ...
- 935
33
votes
1
answer
22k
views
What do you see when your eyes are closed?
If you are in pitch black and you close your eyes, you sometimes can see strange shapes of various colors. A lot of the time these shapes and colors change as you observe them. This phenomenon still ...
- 532
22
votes
3
answers
1k
views
When did vision evolve for the first time?
Today I wondered what the first organism to evolve vision would have been. I assume that it would have been kind of primitive and basic, but of course extremely innovative and eventually useful to a ...
- 583
17
votes
3
answers
2k
views
Are two eyes necessary for 3D vision?
It has always been my understanding that humans have two eyes so that we can have 3D vision: the left eye sees more of the left side of an object than the right eye and vice versa. This helps us to ...
16
votes
2
answers
14k
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?
- 263
16
votes
1
answer
2k
views
Telling distance with one eye
Basic mathematical/logical reasoning makes it clear that you need two eyes to have depth of vision. By seeing an object from two perspectives, our brain can calculate the distance of the object based ...
15
votes
1
answer
6k
views
How does this illusion work?
I found this image on Google+
If you shake your head you can see a portrait of a person. Can anyone explain how the image is constructed in the brain?
- 611
14
votes
1
answer
292
views
Are there specific conditions that allow humans to see ultraviolet wavelengths
It is fairly common knowledge that the lens in its normal state absorbs ultraviolet (UV) radiation. An interesting notion has come up from time to time in my reading that suggests there are a small ...
user3795
12
votes
2
answers
50k
views
Is it safe to look at infrared LEDs?
What happens if one looks directly at infrared LEDs? Sometimes I see this kind of LED at night as red dots and I'm also courious about it.
I was wondering what would happen if one looks directly to ...
- 223
10
votes
2
answers
6k
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 ...
- 103
10
votes
1
answer
36k
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 ...
- 223
9
votes
2
answers
58k
views
Which shades/hues of color are easiest to distinguish for humans?
I'm trying to represent data graphically and am using a variation of hue/lightness to distinguish one data point from the next. I would like to use a color that would allow me to convey most ...
- 6,515
9
votes
4
answers
3k
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 ...
- 208
8
votes
2
answers
359
views
Cerebral activity during exposure to non - visible light
Our eyes only have the ability to sense light within a certain spectrum. My understanding is that particular frequencies energize specific cells in our eyes, each responsible for a different "color". ...
7
votes
1
answer
1k
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 photoreceptors....
- 3,006
7
votes
1
answer
3k
views
What is the function of the human eye white?
If you have a look at the eyes of most animals, you never see the white part unless the eyes are averted. In contrast, humans always have the whites visible because the iris is quite small. The only ...
- 73
7
votes
2
answers
17k
views
Do octopuses have better eyes than humans?
I've read that unlike humans, octopuses have eyes "designed" the "right way", i.e. with the nerve fibers behind the retina, thus getting rid of the blind spot we humans have as well as theoretically ...
- 203
6
votes
1
answer
351
views
What color does the other cone in Tetrachromacy correspond to?
Human with normal vision possesses 3 cones, which correspond to blue (S), green (M) and red (L). What about tetrachromacy, where people have 4 cones in their retinae? What is the fourth cone exactly, ...
- 387
6
votes
1
answer
380
views
Perception of white in the absence of rods
If the retina would not have any cones, one would be color blind. If white is the presence of all colors (in the matter of color mixture, not addition), then what would white look like without rods?
- 1
5
votes
2
answers
3k
views
How are colors outside the standard RGB color scheme perceived?
I found this image in a German book about biology. It's called DIN 5033 and represents the RGB color scheme.
What colors are outside the RGB scheme, i.e., in the black areas of the picture?
- 171
5
votes
1
answer
457
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 ...
- 151
5
votes
2
answers
3k
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 ...
- 2,939
4
votes
2
answers
1k
views
The arrangement of retinal cells?
The section of retina shows a layered arrangement of the various retinal cells. Starting from the inside (where the light strikes first) is the nerve fibre layer, ganglionic layer, amacrine cell layer,...
- 4,679
4
votes
1
answer
2k
views
What determines the shape of the center-surround receptive fields of retinal ganglion cells?
The wikipedia article about receptive fields of visual system tells us the following:
The receptive field is often identified as the region of the retina where the action of light alters the firing ...
- 143
3
votes
1
answer
219
views
Color vision across species
Is it true that color vision is sex-linked for all species with binary sexes? Is there an evolutionary significance to the fact that color vision is X-linked in humans? E.g., only female humans can be ...
- 133
3
votes
1
answer
670
views
Ventral stream pathway and architecture proposed by Poggio's group
Please can you give me a very brief explanation about all functions in the ventral stream architecture summarized in this figure:
This figure is from Serre et al.'s A quantitative theory of ...
- 183