Color Blindness

Color blindness, also know as color vision defects, is the difficulty or inability to tell the difference between some shades of colors. Frustrations for those with color blindness include reading color-coded maps, buying clothing, and traffic lights.

3,932 Questions

Why are dogs color blind?

There's a widespread belief that dogs only see in black and white, but that's just not true—they can see some colors. Structures in the eyes called cones are what allow us to see color, and most humans have three types of cones; dogs, however, only have two—they lack red-green cones and therefore can't really see those colors. They likely appear gray or brown.

As for why that is, dogs' vision evolved to be optimized for hunting in low light, meaning their night vision is ultimately more important than their color vision.

Are both males and females typically affected by color blindness?

Well, both are affected. But it is primarily the males that are affected.

Are dogs colorblind?

Dogs are not color blind - they see color, but their chromatic acuity is significantly less than humans'. This is for two reasons: (1) dogs have far fewer cone cells in their retina (cone cells are responsible for seeing color); and (2) dogs are dichromatic (they see only two primary colors - blue and yellow) whereas humans are trichromatic, meaning we see three primary colors - red, blue, and yellow.

Humans have 7 times higher proportion of cone cells than dogs, meaning that when dogs do see colors, they are pale or faded. However dogs have a much higher concentration of rod cells, which are responsible for seeing black-and-white, and also much more sensitive in lower light conditions. For that reason, dogs have much better night vision than people.
Well actually dog aren't color blind... they can see colors like grey, black, and white, etc. so they are down the middle of blind and not blind. They can only see dark colors.

Have a good day :)
Actually, some dogs can see some colors, like blues or greens. Scientists are still trying to figure out what can and cannot be seen. But, most dogs can see some color, but mainly black and white.
not really they can see colors like us. only dogs have hard time seeing colors that are simaliar in looks like red and orange. sometimes they see colors darker or lighter in color. Some dogs have eye vision that can only see black and white
It is a common misconception that dogs see only in black and white. Cone photoreceptors are the cells in the retina responsible for color vision. They are present in dog and cat retinas. Although dogs and cats do have some color vision, there are species differences in color vision. Humans with normal vision have 3 types of cones. Dogs and cats have only 2 types of cones so they do not experience the same spectrum of color vision that we do. Color vision in dogs and cats is called dichromatic versus trichromatic color vision in people. It is thought that dogs can see blues and yellows the best and that they can distinguish reds from blues but that they have difficulty distinguishing reds from green. They are considered similar to red-green color-blind humans.

Of course, this is what we THINK... Until we find a way to actually communicate with them, we won't be able to ask them to find out for sure.

They are, however, predators so they need color to see prey and potential danger.
Nobody can tell for 100%... you can have one scientist saying yes they are and one that says no they aren't. :( it bugs me too. Scientist are trying to figure it out but still nobody knows fro sure! :(

What animals are color blind?

Some animals are color blind... Just some can see some certain colors, like a horse can see blue's and greens, deer can see yellows and greens..etc...

Dogs most definitely are not color blind. There are some differences in their vison from that of humans, but -- contrary to popular myth, their eyes contain both rods (cells that detect light and movement but not color) and cones (which detect color and need more light than rods do in order to activate).

Rods are groups of light sensors connected to one neuron. Cones, on the other hand, are one neuron per cone and, unlike rods, have a narrow range of wavelengths they'll respond to. Dogs' cones respond to, what in the human range of vision, would be yellow, and blue-indigo.

Most breeds of dogs also do not resolve images well at distance, with a focal range of about 20/70 (to a human's healthy vision of 20/20). This means, what you see at 75' is about what a dog sees at 20' (exceptions are Labrador Retrievers, who approach 20/20 -- which is why they're often used as guide dogs).

Dogs also have a wider angle of acceptance -- around 270 degrees (as opposed to a human's 180 degrees). This means they are more aware of events on the periphery of human sight of course, but as the acceptance angles of vision of the two eyes don't intersect as completely as humans, they don't get really good distance ranging except for a small angle of acceptance directly in front of them.

You can pretty easily test this if your dog likes retrieving. Get a bunch of identical balls in different colors, and watch for the surprisingly different reactions.


Source: Turtles, Tortoises and Terrapins: Survivors in Armor by Ronald Orenstein.

At least some turtles can see in the red-orange-yellow part of the turtles (for example) like to eat berries, and the color vision can help them spot the ripening fruit.

and bees.

Birds are not color blind because you can teach a parrot to recognize colors. This is also true in a peacock's colorful wings.

Good point! While dogs have only two types of cones (see above about cones and rods) that detect yellow and blue-indigo, and humans have 3 (Cyan, Magenta, Green or Red/Yellow/Blue), birds have four, with the ability to see into the ultraviolet as well.


Pure white, shorthaired cats with two blue eyes are often deaf (not blind!)

Pure white, Persian longhaired cats, are color blind.

One in four human males has a form of colorblindness, with differing levels of severity, or acuteness.

Deer are color blind. This is why hunters where blaze orange. It stands out for the hunters, but isn't noticeable for the hunted.

A little more..Because deer don't clearly contrast and react to International, Day-Glo(TM) or Safety Orange doesn't mean they're colorblind. It only means they're not able to clearly differeniate these particular frequencies from others. I'm inclinsed to guess that, when deer graze, the identification of food is partially color identification -- but that's a guess.

In fact, very few if any animals perceive only in monochrome or gray-scale. Barring extreme neuro-trauma, humans never do. Even in cases where severe brain injuries plays a part, the most extreme case I've seen documented (Sax et al, "Anthropologist on Mars") was an artist who, after a severely neuro-traumatic event, could only see in gray-scale and in a very narrow frequency span in the yellow-orange region....

Domestic Ferrets see in shades or tones of gray and can see some red

When was red green color blindness discovered?

It was discovered in 1798 by John Dalton who was himself color blind.

How do you anodize machine bolts to black color?

i am sure you could find out somewhere on the web, but would be easier to just buy anodized bolts or take em to a company that does anodizing

Is the best color of solar cover black blue silver or clear?

I was told by a pool supply store in Cleveland, Ohio, that they have heard of more instances of the black covers falling apart than the others. The guy in the store suggested it is because the black absorbs more of the sun's heat, causing the more rapid breakdown in the material. He had heard nothing about the clear covers, but speculated that it would hold up better than the black. Swimming pool covers help retain pool heat by reducing evaporation. For this purpose, color does not matter. At night any cover will have about the same effect. During the day though, solar energy from the sun heats the pool. You see all sorts of claims from cover manufacturers that their blanket "heats" the pool. This is false. All blankets block some of the solar energy coming from the sun. So which one blocks it the least? According to a government report I read, clear covers block 5-15% of the sun while colored ones block 20-40%. It's clear that clear is the way to go (sorry about the pun). The question then becomes, should I uncover my pool during the day when it is not in use? It depends. On calm, humid days, take it off for maximum heating. On dry, windy days, the evaporation loss outweighs the cover loss, so leave it on. Always leave it on on cloudy days and at night. Dave O

How can you describe the color pink to a blind person?

You can't describe it. The color pink is strictly visual - it is a light of varying wavelengths and frequencies. Just like you couldn't answer what pink sounds like; the color pink will always remain foreign to a blind person.

That is a beautiful question you have. Pink is the soft pillow you felt as a baby or the soothing voice of your mother. You could also describe pink using the sense of taste, such as bubble gum flavored ice cream.

I also think that is an excellent question. Pink is the way you feel when you love someone. Pink is the way you feel when you touch a flower in April. Pink is the way a lollipop tastes on the tip of your tongue.

  • Remember- this person is only blind when it comes to sight, he or she is not blind when it comes to feeling.

The best way to allow a blind person to experience pink is through their sense of smell and touch. Let them smell a rose. Let them feel the petals on the rose, which are tender like a baby's hand.

Pink is a softer version of red.

Is it true that the official color of Ireland was once blue instead of green?

Blue rather than green is the colour associated with St. Patrick and some flags were "St. Patrick Blue" in colour.


Also the Irish flag that still appears on the English Royal Family's coat of arms is navy blue with a gold harp.

It can be seen on photos of Princess Diana's casket if you're curious as to what it looks like.


In response to Claire that's a Leinster flag not an Irish one

Note - That is actually the Irish crest on Diana's coffin and not actually the Lenister Flag. This crest is now used by the President of Ireland.


Hi, I'm born and bred in Ireland so I'm positive that blue not only was once the official colour of Ireland but still is. As a result it is the colour of the carpet in the Dail (pronounced 'Dawl') which is the Irish seat of government.


There is no official colour of Ireland as such. However, St Patrick's Blue and Presidential Blue are the colours that the Government of Ireland use for their day to day business. You will see the two different blues in the Dublin County football colours and on the old Aer Lingus liveries. The light blue is the St. Patrick's Blue, the dark one is the Presidential Blue which appears in the Irish crest. Dark blue with a gold bardic harp. Green is only a customary colour and cannot and should not ever be considered as the official colour. The previous answer is quite correct about the Dáil using these colours in the carpet. There are various examples of this blue being used in many official Irish Government buildings and meetings. Have a look the next time you visit an Irish Embassy to see what colours are on display.

Updated Answer:

Actually, blue has been the national colour of Ireland since the 12th century.

Does everyone dream in color?

Dreaming in Color

Here are opinions and answers from WikiAnswers Contributors:

  • Here's a toughie...Firstly, i think it depends on the person. If a person is old enough, it may occur as black and white. Otherwise though, I'm pretty sure it's mostly color dreams.
  • People dream in color, even when they think that they dream in black and white... if you ask them what color something was, they will know.
  • No, I don't dream in color and I am normal - as normal as possible.
  • Same for me. Sometimes I dream in color, but very often, I have a dream or two in black & white or sepia. And I'm still in middle school, so I don't think you'd consider me "old!"
  • Everyone dreams in color. The thought that we don't dream in color is the result of misinterpretation of very old research. Think about it: We see in color. In fact, we have six senses at our disposal during the waking day. There's no reason we wouldn't have access to those senses during sleep as well, particularly since many scientists believe dreaming is a natural way to recall events and emotions from our waking hours and play out solutions as a means of catharisis.
  • I should add that some people dream much more vividly than others. Those who don't recall dreams at all or very well may be lead to believe they don't dream in color.
  • Humans actually have five senses. Some have fewer -- for example, blind people only have four. People who are blind due to the failure of brain regions devoted to vision do not dream in vision at all. Their brain is unable to create or process visual images. Thus, congenital blind people are indeed unable to dream in color, or in vision at all. It should also be noted that this kind of dream research can only be based on reports from individual.. even if some people do say that they dream in black-and-white, we may never know if that's true, or if they just are unable to remember their dreams vividly enough.
  • No. I dream in color and in black and white. My step father only dreams in black and white and my mother only dreams in color.
  • No one would probably have dreamt of this question if we never had colour tv. As it is, I seriously doubt that anyone who isn't colour blind or has some similar visual disorder, dreams in black and white.
  • This answer really depnds on the person and the circumstanses. Everybody has different ways of dreaming, so many people would have their dreams set in different times (eg. daytime or night time). This may effect the colour they see. Obviously dreams which are set in the night time will be drained of much colour and may be interpreted as 'black & white' dreams. From my experience, dreams of which are set during the night time tend to be black and white as that is all I can make out of colour in the dark.
  • i always dream in color or the dreams i remember are always in color.
  • I read a book about dreams. It's called: Book of Dreams By Sylvia Browne. The color dream is a prophetic dream. Prophetic dreams are always in color! They tell the future. But they only give you hints!
  • Who knows if you dream in color or not? When you remember the dream, you are more likely to remember it in color, since your daylight vision is in color. If you claim to dream in black and white, the chances are you just dreamt a dark dream.
  • Mostly dreams occur in different colours it need not be black and white only sometimes people dream in single colour like red,blue and green but it depends on how the person want to see the brain doesn't rest at all that is why dreams occur so as we think inturn the brain thinks and manipulates and gives it in the form of dreamz...
  • I am color blind, my brother is blind, we both dream in color.

mostly, but some dream in B/W too...

How do color LCDs work?

by injecting the colours in ccfl lamp and it genrate rgb colurs...and

Why is the color red an appetizing color for people?

The Allure of RedSpeaking somewhat physiologically and psychologically, yellow is apparently the most significant colour that makes people want to eat (so a definite bad idea for the kitchen), however probably because we often associate red with feelings and emotions tied in with love, passion etc. Therefore people see it, it's a warm colour, we feel that instant comfort and security etc. Hope that starts you off. Satisfies our primal instinctsNot sure if there is any scientific data, but most humans eat meat and red is a strong indicator of the quality of meat and freshness. Visually speaking, it could mean life or death for the person that chooses to eat that particular piece of meat. People that chose to eat other colors of meat probably died out. So evolutionary tendencies have some impact on peoples desires. The food industry plays heavily on this natural tendency. Hence the popularity of ketchup and pizza - where red is the primary color. I'm sure there is many other examples of this.

It is appealing

Red is an appealing colour. It is eyecatching, and possibly makes you think of apples. Does some muddy brown colour make you want to eat? No, probably not. Red is much nicer, and generally not associated with something gross.

Try it out!

Have you tried eating blue colored rice? I did, and my appetite just vanished completely. I couldn't! Same with a blue cake. I baked it for class, but no one ate it. When you try this, make red and yellow colored rice too.

Is there a way to beat the Ishihara test for colorblindness?

Beat it, meaning cheat on it? Sure. Plenty of ways. You could study the test ahead of time so you know by the patterns what number is there; you could have a non-colorblind friend tell you the answers; you could bribe the doctor... so many ways.

My question though is why in the world would you want to? The test isn't for a grade... it is to determine whether you are colorblind, and that is something that it is helpful to know, because it can affect daily life. For instance, a friend of mine can't tell the difference between two colors when we are playing a certain card game, so he needs someone to check and make sure he really has what he thinks he has.

Maybe if you know this then you can save yourself from larger mistakes at work or school... just by doing something simple like having someone who isn't colorblind check your work.

If you are trying to beat it for the purposes of getting a job, such a pilot or certain types of technician, you need to understand that the guidelines are there for your safety, as well as the safety of others. In certain occupations, colorblindness can lead to fatal mistakes. In those instances, it would be unethical to try to get around this test.

If the color red has totally disappeared from your desktop why has this happened and what if anything needs to be replaced?

My guess is the video card is going bad. Try replacing that. If you have a spare monitor you may want to try viewing your desktop on a different monitor before going out and buying anything.

First thing I would check is the cable between your monitor and computer. Swap it for another cable if you can detach it from the back of the monitor. If not, leave it be. The inside of a CRT monitor is a dangerous place. You can get shocked and killed by the voltages in there.

If it is an LCD monitor, then it would almost have to be a video card or driver issue. If not those two, then it would mean the monitor would have to be replaced. But one color would not disappear completely on an LCD> You may lose it in spots, but I've not heard of a full failure of one color on an LCD.

If it is a CRT monitor, you may want to try replacing that. Long story short, CRT's use 3 colors red, blue and green) to create the image you see on the screen. The three colors are controlled by "guns" built into the tube. Each one is operated independently, but are synchronized to each other. If one gun or the components that control it fail, then the picture would be as you described it.

In summary, try another monitor on your computer, or try your monitor on another computer. Then you can see if the problem is in your computer case or the monitor itself.

For testing, you can either borrow a monitor from someone else, or many computer shops will check this for you. A smaller high tech shop may even have a workbench with a monitor set up for customer use, usually for a small fee.

What is the definition of monochromatic colors?

Monochromatic colors are all the tints, tones, and shades of a particular color or hue. You typically see this on a paint sample card, for example, with lighter and darker shades of the same base color.

Does eye color determine color blindness?

Eye color has nothing to do with whether you are color blind or not.

Are sharks color blind?

Sharks can only see in shades of grey.

Findings from a study by Australian scientists, released in September 2012, show that sharks' eyes have just one type of cone opsin - or light-sensitive proteins found in the photoreceptor cells of the retina - instead of thevtwo or more that are needed to see colour. Cone opsins are used to help animals see in bright light, and to differentiate between colours.