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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What is the possibility of retinal damage from light flashes? [closed]

During the process of Fluorescein angiography, flashes of light (which are intense enough to make one wince) are used to photograph the back of the eyes. For several minutes after the procedure, ...
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2answers
59 views

Improving myopia

I have a friend who no longer needs glasses. He previously had myopia in both eyes but over the years it has improved until he no longer needs glasses clinically. He's had glasses for over 30 years ...
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44 views

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

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 ...
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90 views

The process of how you visually perceive objects?

Use the following terms to describe in detail how you visually perceive an object that you can see right now. Use the terms in order to correctly describe the sequence of events involved in your ...
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45 views

Dogs bark at familiar person in Santa costume. Why? Don't dogs trust smell over vision?

Last night 10 humans and 2 dogs spent Christmas together. At some point, one human dissappears for a few minutes and comes back wearing a full Santa outfit. Upon respawning, the dogs start barking ...
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59 views

How is color information transmitted from eye to brain?

Is it frequency-modualated or are different colors transmitted by different axons? I know that each ganglion cell is connected to multiple photoreceptors. How does it tell the brain which ...
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40 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
83 views

Why don't we have more cone cells (bigger fovea)?

Background Apart from being able to sense color, cone cells are able to perceive finer detail and more rapid changes in images, because their response times to stimuli are faster than those of rods. ...
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Haidinger's brush: Is this a by-product of the eye's physics, or are there any evolutionary grounds for it?

The human eye is, very subtly, sensitive to the polarization of light. This is an effect known as Haidinger's brush (see Wikipedia article of this name). What, if anything, is known or at least ...
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1answer
87 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 happened if one looked directly ...
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1answer
49 views

Radial Basis Function Network (RBF Network)

In the Wikipedia article on radial basis function network, I didn't understand what was meant by "center vector for neuron i", in other words "center of the RBF units called also prototype".
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The Operation of tuning in the S1 layer of ventral model

According to my previous question in ventral Stream pathway and architecture, I want now to get a brief example about how the S1 layer is constructed. In other words, how all the simple units are ...
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1answer
134 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 ...
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2answers
819 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. ...
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2answers
101 views

Why do our eyes “wrap” hue from UV to IR?

On the high-wavelength side of things, we see almost-infrared as reddish, with a slight tinge of magenta. On the low side, we see violet fading into the same magenta color. Why is that? You can see ...
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1answer
111 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 ...
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1answer
87 views

Was life less colorful before color vision evolved?

According to Wikipedia, we know that color-vision photopigments appeared in the common ancestors of tetrapods and fish at least 360 MY ago. Would life have been less colorful before the evolution of ...
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189 views

Reason for seeing grid-like patterns when strobing a solid black-white image?

I was trying to do some stimulation for SSVEPs by strobing a solid black square and a solid white square. Weird thing was, I ended up seeing weird grid like patterns that looked like this, always of ...
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1answer
126 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 ...
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Do people with colorblindness have less cones or no cones of a certain type?

https://en.wikipedia.org/wiki/Color_blindness#Red.E2.80.93green_color_blindness Protanopia (1% of males): Lacking the long-wavelength sensitive retinal cones,   Deuteranopia (1% of males): ...
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4answers
177 views

Are there animals which can see movements better than shapes or colors?

I remember that in Michael Crichton's novel Jurassic Park, Tyrannosaurus Rex was supposed to have movement based vision. (Of course, that is a novel and not a scientific text.) I have also noticed ...
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3answers
125 views

What exactly is the neural receptive field?

Neural receptive fields map the spatial or temporal distribution of the data to individual neuron excitation, if I understand correctly, but I do not understand if receptive fields (especially in the ...
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1answer
100 views

Are these claims of “revolutionising” understanding of human vision and hearing valid?

I've started a hobby machine vision project (and posted some questions to this end on other SE sites) and on a side track, also been looking at relevant research in human vision (and partly, hearing). ...
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1answer
4k 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 ...
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1answer
73 views

Animal UV vision

It is reasonably well known that many species, such as bees and some types of birds as examples can see into the ultraviolet (UV). How is the structure of their eye different to humans to allow this? ...
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1answer
42 views

The Eye, and Camera Lenses

How do near sightedness, farsightedness, and normal sightedness work? If the eye is accustomed to one small focal point, how can it manage a wall of light? And also, how does it process the small ...
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What processes are responsible for focusing on an image only seen by one of the eyes?

When a person is spying from around a corner with only one eye, it's rather easy to ignore the other eye's image, since it's probably much darker, because one usually spies around a corner standing ...
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1answer
124 views

Why are trichromat cone cells unable to sense ultraviolet and infrared radiation?

I understand that cone cells vary in the color they sense, is this because of wavelength, frequency, something else, or a combination of the previous? I also understand that tetrachromats can see an ...
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2answers
115 views

What gives observable light its colors? [duplicate]

I know that difference between different colors of light is difference between their wave length but I don't know what gives beautiful colors (like rainbow colors) to different wave length of ...
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83 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 ...
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3answers
93 views

Is it technically possible to make someone see something when their eyes are closed?

I'm writing a little article and need any information about how human vision works and latest technologies and discoveries around. Actually its not a professional article. Its for a group of my ...
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1answer
147 views

What is the brightest color a light source that only emits blue frequency light can achieve?

Let's say there is a luminous light bulb that only emits blue light, and you (or a camera if you prefer) look at it from a close distance. Will the maximum brightness perceived not have any "white" to ...
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1answer
64 views

Is there an optimal illumination level for human habitats/workplaces?

I know of melanopsin, a photo pigment in mammal eye that helps regulate circadian rhythms. It responds most strongly to blue spectrum light. There have been experiments that demonstrated that ...
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2answers
463 views

What is the difference between a circular and a cat's-eye pupil?

I've been to local zoo the other day and one lizard caught my attention: its pupils are circular, which, I thought, is not usual for reptiles. Turns out it is, but now I can't find any explanation on ...
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HSL Lightness vs Eye sensitivity

In a monochromatic spectrum, is the human eye equally able to distinguish between lighter colors just as it is in distinguishing between darker colors? I mean is there really a linear relationship ...
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404 views

Does every human eye see the same visible spectrum?

It is said that human eye can see light with wavelength approximately between 400nm and 700nm. Are these upper and lower bounds same for every human? If not, what are the means and standard ...
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1answer
268 views

Why do we squint?

Recently, I was having an eye exam and admitted to squinting my eyes to sharpen blurred edges. Later, while waiting for the dilation to set in, my brother (a would-be pharmacist fresh off an anatomy ...
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1answer
622 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 ...
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2answers
95 views

Possibility of orthogonal view for a creature?

Just a pure curiosity: Does there exist a creature with an orthogonal view to the world instead of perspective? What would be an optical explanation for possibility/impossibility?
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167 views

Why does vision go blurry after microscope use, and how to prevent it?

After using a binocular microscope recently for about 20 minutes, my vision went blurry and for an hour or so it was much harder to read small text. This occurs to a (far) lesser extent whenever I use ...
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1answer
151 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 ...
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1answer
511 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 ...
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2answers
4k 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 ...
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1answer
198 views

Can visual acuity be improved?

Is it possible to completely cure myopia using natural methods (i.e. not with Lasik etc.)?. I have seen websites claiming that exercising the eyes will help improve eyesight. Is this true?
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363 views

Why does squinting allow you to see objects more clearly?

How does squinting alllow one to see clearer pictures? What are the harmful effects?
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1answer
51 views

Does retinal detachment happen more frequently at night?

My understanding and experience is that during the night photoreceptors are less tightly coupled to the retinal pigment epithelium. Does this make it more likely for a retinal detachment to happen at ...
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5answers
635 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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1answer
317 views

Why does this illusion work?

This is another image I found on Google+ All lines are absolutely straight, parallel and perpendicular but why does it appear to have a curvature? Related: How does this illusion work?
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1answer
1k views

What negative effects can pinhole glasses have on the body?

While shopping in the local supermarket yesterday, I was surprised to find this display on one of the shelves. I also realize that I should have taken a pamphlet with me, as well as a picture of ...
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How do optical illusions work? [closed]

Hello fellow investigators I have two questions about optical illusions 1) A photo mosaic is something like this http://i.stack.imgur.com/Pzplp.png What are the optical principles behind our eye ...