Questions tagged [eyes]
The discussion of the anatomy and evolution of eyes. Consider using the "vision" tag for questions regarding how the brain interprets information from the eyes.
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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?
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How do our eyes detect light at different frequencies?
Here is my confusion: we can see colored light of different wavelengths: form red to violet. To my understanding, these stimuli cause a confirmational change in the photoreceptors in our eyes and ...
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How do birds deal with their eyes drying out at high speeds?
My eyes tear up when cycling at 15 mph, which is nothing compared to bird airspeeds.
Do birds continuously produce lots of tears and blink a lot, or do the eyes self-moisturize from the inside ...
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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 ...
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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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How does laser surgery correct accommodation problems?
When someone undergoes laser surgery to improve eyesight, how does it correct accommodation problems?
Why does it not help presbyopia?
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Which part of human eyes is getting tired?
It's a thing of common sense that if you read, drive or look at computer screen for too long your eyes will get tired. They burn, itch and try to close all the time.
But I was wondering which part(s) ...
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Is it biologically possible for an adult's eye color to change?
Can it be that the adult eye can change color? Specifically my question is about a unilateral color change, such that the color of one eye remains constant, while the other changes color over time. ...
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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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Why do eyes water in response to particular emotions?
It is common for people to experience very moving situations (sad movies, etc) and have a physical reaction to it (such as crying). I am curious about how emotions can physically lead to the act of ...
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How long do your eyes need to adapt to darkness and reach full contrast?
I heard you should wait some time until your eyes adapt to darkness and are able to see smallest luminosity differences, otherwise you might overlook faint objects in the ocular. Are there any rules ...
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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 ...
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Why do dog's eyes glow green on a photo?
Taking my current profile picture as a prominent example:
This photo has been taken with flash. As I gather, this is the same effect that makes a human's eyes glow red on photos, namely the ...
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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?
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What's the minimum distance of focus for the lens of a human eye to reach maximum flatness?
According to the Wikipedia article on eye accomodation, the range in which a human eye can focus is from 7 centimetres away up to essentially an infinite distance. Of course, people can't see things ...
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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
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Why do human eyes glow red on a photo and dog's eyes green?
Previous Research
I know that cameras sometimes come with an anti "red eye" functionality that involves two flashes, presumably the second flash coincides with the shutter opening.
Question
Why do ...
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Is it possible for two brown-eyed parents to have blue-eyed child?
Here's the (real) story: A young man has stunning blue eyes. On his mother's side are lots of instances of blue eyes, but on his father's side is no history of blue eyes. Both parents have brown eyes.
...
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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 ...
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Why can cats interpret things on a monitor/tv, but dogs cannot?
E.g. you can see a lot of videos where cats are smashing some mouse or spider on an ipad, but I have never seen it with a dog. I have a dog myself and I know that he sometimes responds to the sounds ...
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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 ...
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Do animals with their eyes ~180 degrees apart have depth perception?
Lots of animals have their eyes more on the side of their head, like an octopus or a parrot. Are animals with eyes more on the side able to tell the depth of objects at different distances? It seems ...
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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 ...
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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". ...
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Is the bipolar neuron of the retina considered a sensory neuron?
Any neuron that participates in sending impulses from receptors to the CNS are referred as sensory neurons. But I often see bipolar neurons of the eye (which according to the above definition should ...
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What causes the colors we see in eyes?
Genetics aside, what are the biochemical reasons for the different colours of human irises?
Also, related, how does eye colour change, particularly in childhood? (example: my eyes used to be blue,...
user3795
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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 ...
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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 ...
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What is the science behind the inaccurate perception of colors?
If I go into a green room (all walls are semitransparent and green) and spend some time - around 10+ min - in there, when I come out all my eyes see is white as pink. I see no (or very few other) ...
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What is the eye muscle status when you stare at distant view through a glass wall?
The book said when you look at object close to you, the eye muscles contract and vice versa. I wonder what will be the status of the eye muscles when I stare at distance view (such as a mountain) ...
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Why do our eyes close when we sleep?
Why do our eyes close when we sleep? Is it to relax our eye muscles? How can it be explained from an evolutionary point of view?
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Perception of artificial light - flickering
I noticed something strange a couple of years ago. I was walking down the street at night, when it struck me that the street lights were flickering. But, when I turned to take a direct look at the ...
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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?
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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,...
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Could there be any effects from low powered infrared being used to track eye movements long term?
Basically, looking into infrared LED's and a camera with an infrared bandpass filter for tracking eye movements; my concerns are whether there would be any potential negative long term effects from ...
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Amber eye color in Neolithic Africa
Given what we know of the genetics of eye color and their historical distribution, is it possible or at least plausible for a person born in the Horn of Africa during the early Neolithic (ca. 9000 BCE)...
user5661
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Are human eyes equally sensitive to AC, and DC lamps?
Definitely anecdotal.
This friend is hypermetropic, and uses reading glasses. He doesn't have major issues facing car headlights, or using a torch (the one with a bulb - not a white LED). Yet place ...
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Can we directly stimulate M cones in retina with current technology?
I wonder if we could try to see imaginary "supergreen" color by directly stimulating M cones. For this I suppose we'd need:
Non-destructively scan specific human's retina to locate exact positions of ...
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How do our eyes see an inverted image? [duplicate]
How exactly do our eyes see an inverted image of what we are looking at?
Does it have something to do with the shape of our lens (i.e. convex)?
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Is it safe to look indirectly at the Sun?
I.e., is exposure of sunlight onto the peripheral vision less damaging than exposure onto the fovea?
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Why are human eye colours limited?
Related to the question What causes the colors we see in eyes?, I am wondering why human eyes are restricted in colour. Most common eye colours are blue, green and brown. Why not yellow, orange, ...
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