What I would like you to do is to find a topic from the chapter you read for Monday that you were interested in and search the internet for material on that topic. You might, for example, find people who are doing research on the topic, you might find web pages that discuss the topic, you might find youtube clips that demonstrate something related to the topic, etc. What you find and use is pretty much up to you at this point. But use at least 3 sources.
Once
you have completed your search and explorations, I would like you to
say what your topic is, how exactly it fits into the chapter, and why
you are interested in it. Next, I would like you to take the information
you found related to your topic, integrate/synthesize it, and then
write about it. At the end, please include working URLs for the three
websites.
Once you are done with your post make list of the terms and terminology you used in your post.
Let me know if you have any questions.
While reading chapter 5 I really enjoyed learning about impairments to some individuals color vision, because I have always been fascinated in learning how differently they view the world around them from how I perceive the world. I don’t think it is something we could ever understand, unless we were able to experience it ourselves. I also like learning about how different areas of our brain serve specific functions, and how a person would have to adapt to not having a previously possessed ability, like color vision, after suffering damage to that area of their brain. Achromatopsia is a congenital eye defect that results in severe color blindness, poor detail vision, and photophobia. Photophobia is sensitivity to light. This is a hereditary condition that occurs more often in men than women. It is not progressive, and will not lead to complete blindness. The two types of photoreceptor cells in the cornea, rods and cones, are responsible for different functions of vision in the human eye. Rods specialize in allowing us to see in scotopic, or low, light levels, while cones provide sharp vision, color and contrast discrimination. The three different types of cone cells are responsible for our color vision, and they are packed by the millions into the macula of the retina. The peripheral retina is made of rod cells, and these cells are more sensitive to light but cannot differentiate color. People with achromatopsia have defective cone cells, and must rely on their rod photoreceptors for vision.
There’s a variety in the severity of symptoms of achromatopsia, with the most severe being called complete rod monochromatism. With complete rod monochromatism, there is a complete lack of cone function. Individuals suffering from this variation of achromatopsia, are extremely sensitive to light, even in normally light indoor rooms. They also have symptoms of poor visual acuity and nystagmus, which is involuntary movement of the eyes. Some other less severe variations of the disorder are called incomplete rod monochromatism and blue cone monochromatism, depending on which cones are affected.
Achromatopsia is an inherited condition, requiring both parents to contribute a gene for the condition to occur, which is very rare in today’s world. There is one group that has been studied in the Western Pacific that has a high incidence of achromatopsia. Through genealogy, it was traced back to 1775 to one man who survived a typhoon that killed most of the island’s residents. This man had a mutation of the CNGB3 gene, which is essential in the eye’s photoreceptors and ultimately vision. He passed this gene on to descendants who have subsequently been affected by achromatopsia. Today, 6% of the population of the small island of Pingelap has the condition.
A new treatment for individuals with achromatopsia is the use of red central soft contact lenses. These contact lenses have a small red circle that when properly positioned looks like the pupil of the eye. On the eye they appear as dark circles looking just like the normal pupil of the eye. These red contact lenses not only reduce the light entering each eye, but allow primarily red light to enter the eye. Red light allows the remaining rods to function better, and in complete achromatopsia, where the patient sees no color, the person isn’t aware of the red hue. In the incomplete form of achromatopsia, patients have reported that the contacts enhance their ability to detect red stoplights and red brake lights.
I am happy to learn that scientists and medical professionals are working on ways to help individuals with achromatopsia see more clearly, and live slightly fuller and safer lives by improving their ability to drive and view the world around them. I cannot imagine the differences they must experience in how they perceive our world from how I perceive it. I think it would be interesting to be able to see through someone with achromatopsia’s eyes for a day, to better understand how different the world appears to them.
Sources:
http://www.visionrx.com/library/enc/enc_achromatopsia.asp
http://www.eyeassociates.com/understanding_achromatopsia.htm
http://www.achromat.org/what_is_achromatopsia.html
Terms: achromatopsia, photophobia, scotopic, complete rod monochromatism, visual acuity, nystagmus, incomplete rod monochromatism, blue cone monochromatism, red central soft contact lenses, pupil, hue
http://www.oliversacks.com/books/island-of-the-colorblind/ Have you read Island of the Colorblind? It's a fascinating book by Oliver Sacks, the neurologist. You should check it out! Perhaps use it as a project for the course or just for your own personal enjoyment.
I researched further on the hereditary disorder called Achromatopsia. I chose this topic because after learning all about how normal eyes work, I like to know about what the odd cases, where everything is far from normal. Achromatopsia really popped out to me in the chapter because they really didn't do a lot of talking about it, and I wanted to know more!
Achromatopsia is a rare hereditary disorder that affects only 1 out of 33,000 people. (I also read that it affects 1 out of 40,000 births.) Either way, it is extremely rare and unfortunate. It is brought on to offspring from both parents. If both parents have a diseased gene, there is a greater chance that they will have a child with Achromatopsia. Parents who have the diseased gene will not get Achromatopsia, because in order to get it, both of the paired chromosomes for the individual need to be present. If a couple has one child with Achromatopsia, the chances that the rest of their children will be born with this disease is 1 in 4. Also, there is a 50 percent chance that their children will have the diseased gene, to pass on to their children.
Achromatopsia is an abnormality to the retina. Normally we are born with three different cone receptors in the retina called the red cone, green cone, and blue cone. These are better indicated as S-cone, L-cone, and M-cone (short, long, and medium), indicating the type of light wavelengths. People who are born with Achromatopsia, are born with non-working cones. Although, their rods work just fine, the rods are mostly used to see in the night, or dimmer light. Thus, when Achromatopsia victims are faced with bright light, it is extremely painful. Achromatopsia patients can also be titled "rod monochromats". Meaning that they are truly color-blind and have no working cones.
Thus far, doctors have not found any kind of cure of this disease. Because it has to do holy on genes, it is extremely difficult to find help. Although, they have found things to help with some of the symptoms. They have come up with what they call red-centered lenses. These are contact lenses that help with the amount of light getting into the eye. As we know, Achromats are extremely light sensitive. What these lenses do, is dim their overall light consumption, so it is easier to see outside and under florescent lights indoors.
Driving, as one can only imagine, would be very difficult for an achromat. One youtube video I found was a testimonial of a man who talks about his experience being an achromat. He talked about driving and how important it is to be able to do in your every day life. Most people don't even realize how much driving effects their lives, and with this disease it is almost impossible. Although, this man has taken tests and classes to learn how to drive under his special condition, with the help of a device that attaches to his glasses to make his vision more adequate to drive.
http://www.youtube.com/watch?v=uEbwKCNlUEA
http://www.aapos.org/terms/conditions/10
http://www.achromat.org/what_is_achromatopsia.html
Terms: retina, s-cone, l-cone, m-cone, rods, Achromatopsia, rod monochromats
Good post! We are intrigued by the abnormal and the things in the world we don't typically experience. http://www.oliversacks.com/books/island-of-the-colorblind/ Have you read Island of the Colorblind? It's a fascinating book by Oliver Sacks, the neurologist. You should check it out! Perhaps use it as a project for the course or just for your own personal enjoyment.
I found the topic of color vision in animals really interesting from chapter 5. Like we discussed in class, it is really something that as humans, we will really not understand or be able to experience color vision as a certain animal for obvious reasons. In the animal kingdom, color serves two main purposes which are food and sex. Colors can be used to distinguish between poisonous and healthy food, as well as ripe and unripe food. Flowers use certain colors to be attractive towards bees and other creatures. Color is also used in elaborate patters on animals to be used as a sexual distinction and used in competition for mates. Color can also be used as a tool of communication. This can be seen when observing fireflies. They signal each other by using bioluminescense. Color constancy is something that is important to a lot of animals in the animal kingdom. Regardless if they are a dichromatic, trichromatic, or tetrachromatic animals, recognizing “good” and “bad” colors is important in terms of survival.
Bees, for example, have color vision that is five times faster than humans. They have a very complex eye,c onsisting of over 5000 ommatilidia. They use these receptors to see different wavelengths of colors. They are also able to see ultraviolent lights, something humans are unable to do. Earthworms have very simplistic light receptors which allow them to determine if they are in danger or not by knowing when they are exposed to multiple hazardous lights. At the other end of the spectrum, the animal with the most complex eyes is the mantis shrimp. They have more than double the amount of ommatidia (simple coned-shaped lenses) and with at least a dozen distinct photoreceptors. Fish, interestingly enough have pretty good visual systems, compared to some species of birds even. Some species of fish have their visual systems peak at ultraviolent photoreceptors, because they move about in a blue environment and would need to distinguish between food and things in the background. Fish that are found in the deeper parts of the sea have different visual systems because of the loss of light intensity versus those fish that are towards the surface. Visual systems in reptiles are pretty good as well. Most reptiles have the added benefit of thermal vision pits in addition to their eyes, extending their visual capacities to thermal. Interestingly enough, bulls are unable to distinguish color, therefore, bulls do not hate the color red, rather they charge at the moving cape and not just because it is red. The color red just helps the human spectators be able to see the cape.
http://www.webexhibits.org/causesofcolor/17.html
http://news.discovery.com/animals/bumblebee-color-vision.html
http://www.talkorigins.org/faqs/vision.html
TERMS: bioluminescense, dichromatic, trichromatic, tetrachromatic, ommatilidia, receptors, photoreceptors, ultraviolent photoreceptors
Interesting post. I took a comparative neurophysiology course at UNR and we discussed the mantis shrimp. It's visual system, let alone color vision, is so complex I'm fairly sure even the experts on the mantis don't really understand completely how it works. Also, there are all these e-vectors and m-vectors that are detectable by some animal species (bees and birds I think) that allow them to perceive planes of polarization, which is something we don't really think about with respect to human vision. Also, it has been hypothesized that magnetite crystalline structures within the neurons of some species of giant sea turtles allow them to navigate in the ocean based on the magnetic fields of the planet (used roughly as a lat/longitude marker). Just an amazing amount of things that we don't have direct phenomenological access to as human beings.
I chose to do my topical blog on rods and cones, because they were the thing in the chapter that I found most interesting and useful in understanding sensation and perception. Rods and cones are photoreceptors located in the retina that help us interpret our environment. The main difference between rods and cones are the visual pigments involved. They also have different shapes, cones are actually shaped like cones and the rods are shaped like a rod, that is also the origin of their names. In the retina there are about 120 million rods and about 6-7 million cones.
The cones in the eye are responsible for color detection. There are three cones the S-cone, the M-Cone and the L-cone. The cones are much more concentrated than the rods. The rods are dispersed more toward the outer edges of the eye. The cones lie in the center of the eye in what is known as the macula (a yellow spot in the eye) in a region about .3 mm in diameter known as the fovea centralis. The cones are less sensitive to light than the rods, which is why they are more so responsible for daytime vision. This is why we cannot see color very well in the dark. Cones are not sensitive enough to detect it without adequate light. Although the cones can adapt much more quickly to varying light levels because they have a faster response time than the rods do. Cones are also responsible for high-resolution vision. The eye is constantly adjusting to keep viewed object on the fovea centralis in order to be able to perceive the object as clearly as possible.
The rods are responsible for our night vision, motion detection and our peripheral vision. As mentioned previously there are far more rods than there are cones and the rods are more sensitive than the cones are, in fact it is estimated that rods are up to a thousand times more sensitive than cones. Rods are responsible for our scotopic vision or our dark-vision. Rods have a much slower response time than cones do. The dark-vision is obtained gradually and can take up to 30 minutes for some people because the Rod adaptation process is longer than the cones.
We can actually detect motion better in our peripheral vision areas, the places the rods are, than we can in the center of our eyes using our cones. The rods in the human eye are much more sensitive to motion and being that they are actually on the outsides of your eyes you are better able to detect the motion with your peripheral vision.
Humans have actually found ways to manipulate the.. lets call them limitations, for a lack of a better term, of the visual system over time. Instruments on ships use red light because the rods do not respond to red. The captain is able to use all of his dark vision and look at the instruments without having to re-adjust to the darkness. This makes him better able to watch for ice burg, other ships ect. Also back in the day, pirates wore eye patches to help them better adjust their night vision/day vision throughout the day to their location on the ship, not because they were all missing one eye. Pirates spend time on a boat in the middle of a sunny ocean. If they are on deck they need to have their day vision, using the cones of their eyes. When they need to go under the deck and get some rum or something (hehe) they need their night time vision. By wearing an eye patch they can switch back and forth between day time and night time vision with out having to wait for their eyes to adjust. They can just go about their day switching their eye patch to adjust to various light conditions.
Terms: rods, cones, photoreceptors, visual pigments, macula, fovea centralis, Scotopic, S-cone, M-cone, L-cone, peripheral vision,
http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html#c3
http://en.wikipedia.org/wiki/Eyepatch
http://www.cis.rit.edu/people/faculty/montag/vandplite/pages/chap_9/ch9p1.html
http://www.vetmed.vt.edu/education/Curriculum/vm8054/eye/RODCONE.HTM
I had no idea the eye patch was used for functions other than pirate/captain fashion. Haha. Also, hopefully most of them aren't swiggin' rum while on the clock, after all there have been all of these accidents involving inept captains of large ships. Anyway, glad you learned some cool stuff about the functions of these receptors with different sensitivities to light.
Color vision overall is an interesting topic for me, why because not only as person am I dependent on color, but as a person that loves the arts. I’m constantly working with colors with my artwork and I’ve always been mildly paranoid of what would happen if I lost my vision. So when artists and how they’ve managed with color blindness or general blindness came up in class it caught my attention. So I searched out some things on the topic, specially the injuries that had occurred for the person to lose their blindness.
Color blindness, can be caused by the regular means of heritability; that a person has a lack of certain cones that allow a person to see a color. Glaucoma, macular degeneration, cataracts, and some illnesses that can cause vision issues later in live. Retinis Pigmentosa or RP is a disease characterized by the progressive death of photoreceptors and degeneration of the pigment epithelium. Head injuries as well have been related to cases of blindness or distorted vision. In some cases a head injury can cause the retina of the eye to become detached. The retina is a light sensitive membrane in the back of the that contains rods and cones, which receive an image from the lens and sent it to the brain through the optic nerve. Mild to severe concussions can cause optic nerves in the brain to mis-fire, or not receive the signal that is being sent to or from the eye, which results in impaired or loss of vision. The optic nerve is the second pair of nerves, which a raise from the retina and carry visual information to the thalamus and other parts of the brain. Strikes to the head can also cause blood vessels to burst and blood will leak into the vitreous humor, the vitreous humor is the transparent fluid that fills the vitreous chamber in the posterior of the eye. This is probably the least problematic, as it usually with time fixes itself, and some medication can help hurry along the process.
All these problems are caused by simple things, probing just how fragile and complex the brain and eye is. That a simple thing can cause a large or small issue, even a whiplash from a car accident can cause issues. But what’s the cause on the person is of more interest to me. And in two cases I found it inspiring that even with their challenges, two women were able to continue what they love. One a painter, and though she was legally blind she still had some vision. She had to learn to paint in a different way, intensify colors so she could see through her challenge and continue what she enjoys. Another woman that did her own jewelry and pottery as well who was nearly completely blind still managed to continue. Though they had to face that they would never do the same work has they had prier they had to change their thinking and their ways of doing the art, and accept challenges and push themselves to survive on their own.
Terms: color vision, Retinis Pigmentosa, retina, optic nerve, vitreous humor, rods, cones,
http://www.ellwoodcityledger.com/news/local_news/loss-of-sight-doesn-t-darken-artist-s-vision/article_b6eafd20-8566-5336-ba8f-5ceb4187dc8d.html
http://www.nj.com/hudson/index.ssf/2012/01/jersey_city_artist_teaches_bli.html
http://www.everydayhealth.com/vision-center/head-injuries.aspx
http://www.webmd.com/eye-health/acquired-color-vision-problems
There's a great chapter in Oliver Sack's book, "An Anthropologist on Mars" that talks about a painter who loses his ability to perceive color. Very interesting piece about how this changed his life and work. You might enjoy giving it a read.
As I talked about in class color constancy was of significant interest to me. In reading about color in the chapter I read that we actually do not see color at all. What we see is wavelengths. The amount of wavelengths of light that hits our eyes is dependent upon the illumination at a specific time and also the amount of light that is absorbed by the object that we are viewing. With that our brain then perceives color for us. All of this makes sense to me, but what I struggled with was understanding how it could be that we are able to perceive something as the same color in all different types of illumination. My reasoning for this is that when the illumination changes an object no longer absorbs or reflects the same amount of light, so the color should change. I know that if this were so our lives would be a lot tougher. I am glad it is the way it is but it is just something that is hard for me to grasp. With that in my mind it seemed like a great concept to do further research on.
Since color is something that is created in the brain it is obvious that this process must start at the retina. The retina is where the photoreceptors are located. The photoreceptors that play a role here are cones because they perceive color. In my research I learned that there are specialized neurons in the brain that compute cone activity. If there were not neurons that were able to compute the activity of certain cones then there would be no way for colors to be held constant. These are referred to as double opponent cells because not only do they compute color opponency, but they also compute spatial opponency.
This whole color constancy thing works because the brain is able to discount differences in illumination. The brain has the ability to do this because changes in illumination have an effect on the entire image that the retina receives and not just a part of it. Studies were done in order to evaluate what happens to our perception of color when things are view in isolation instead of altogether. The result of studies like this show that color may be misinterpreted when they view this way. Edwin H. Land created a collage of multicolored geometric patches to study color. A patch of red on the Mondrian may be viewed as orange if there are not other colors around for the brain to compare it to. It is amazing how our brain is able to compare and contrast in order to come to conclusions on visual things.
Edwin H. Land was the co founder of Polaroid. Besides his work with the Mondrian and Polaroid land is also the creator of the retinex theory. This theory states that both the eye and the brain are involved in processing. Early research was done by neurobiologist in London where they studied the brains of apes because there are homologous regions in their brains. With the use of pet scans researchers are able to directly study humans nowadays.
The more I did research on color constancy the more complex it appear to me. It is so essential to our overall color vision however. I am just glad that my brain is able to do this for me without me having to think about it.
Key terms: Color constancy, illumination, retina, neurons, photoreceptors, Cones, homologous regions
http://www.webexhibits.org/causesofcolor/1D.html
http://www.psychologicalscience.com/perception/2012/02/topical-blog-week-6-due-thursday.html
http://en.wikipedia.org/wiki/Color_constancy
It's pretty interesting that we can engage a process constantly to help us experience the external world, yet we can not really understand this process without learning a lot about it. Our brain knows how to do it, but we don't really have an innate understanding of how it does this.
The section I was most interested in was “Does everyone see color the same way”? Since this entire chapter involves color I found it interesting that such things cause abnormalities where so many different conditions don’t allow people for the same perception of color as I personally do. My general interest is not over just one specific word, but a few. I take a general interest in the concept of color blindness, or achromatopsia. In my highschool I knew a friend who was color blind though it is a fairly rare diagnosis with 1 in 30,000 people having the disorder. Achromatopsia is due to central nervous system damage. It is important to note that color blindness for individuals is not all the exact same. There happens to be a number of different types of color blindness. Cones play an important role in determining how we perceptually see color. Cones involve the vision we see in daytime, as well as color and visual acuity. Cones are just one type of photoreceptor (light-sensitive receptor) that is seen at the retinal level. There are S-cones, M-cones, and L-cones, each of which may be absent in certain people. The absence of an S-cone is called tritanope, the absence of the M-cone is called deuteranope, and the absence of an L-cone is known as protanope. Each one of these is specified as a different type of color blindness. Achromatopsia is interesting because of all the different ways which color blindness can occur. For example there are in fact certain people who can only see black and white; you might say full color blindness. However, there are also individuals who see color, but have problems in distinguishing only certain colors like red and green. The term color space also fits into the disorder of achromatopsia. Color space is the three dimensional space based on our three cone types of color perception. There are individuals who lack the ability to be aware of their three dimensional visual system component. To further continue my interest in color deficiency and other related nervous system or brain damaging conditions, Agnosia and Anomia also commonly related terms similar to achromatopsia. Agnosia is characterized by the inability to recognize objects though having the ability to see them. There was not a whole lot mentioned about this particular condition. It may be related to strokes or dementia. Most typically this condition is related to some sort of damage to the brain. Anomia on the other hand, is the inability to name colors. Anomia is a type of aphasia that effects language and communication. Sometimes anomia may include memory loss or a decline in intelligence, but not typically. Individuals with anomia are able to carry out everyday functions such as work or hobbies, though communication and naming objects will still be effected.
Terms: Achromatopsia, cones, photoreceptor, color space, agnosia, anomia.
http://en.wikipedia.org/wiki/Achromatopsia
http://en.wikipedia.org/wiki/Agnosia
http://www.healthline.com/galecontent/anomia
Interesting. I would say people definitely do not see color in the same way, based on the genetic variation in the opsins that code for certain photopigments associated with each cone type. The cool thing is that people have different spectral sensitivities to wavelengths of light based on this and so likely experience the world a bit differently.
Afterimage:
Opponent colors are colors that Ewald Hering describes as opposites and therefore are “illegal.” In addition to this the opponent color theory helps us to understand that some colors are opposites. Negative afterimages help us to further comprehend this process. When a negative after image occurs you begin focusing in on one specific color and then when you look away your cones have become so exhausted or over stimulated by this that they see the opposite or opponent color on the color spectrum, thus we have negative afterimages. Another important piece of information to understand about these opposite colors is that they are also complementary. From more artistic point of view this means that these colors when paired up help each other look better or make each other more appealing! This also explains why this process relates to the chapter which is all about the fascinating process of color vision.
While negative afterimages are a normal retinal process of the eyes for most human beings some individuals on certain medications or with certain medical problems experience negative afterimages in a much different way that causes disturbances for daily life. This is considered a problematic process of the brain rather than that of the eyes because it of its link to medications. This visual issue is known as palinopsia and once it starts, doctors having a difficult time identify the source.
In addition to this information there are a few other interesting facts to point out. The first being that since afterimages happen in the retina you can close one eye, stare at a funky design that produces a negative afterimage and then produce the negative afterimage in only one eye, weird! Also there is a process that is the opposite of the negative after image called the positive afterimage which on the other hard is much more difficult for researchers to break down and understand, what is know is that they are related to retaining a color when you look away from the optical illusion in contrast to seeing the opposite negative afterimage.
Terms: afterimage, negative afterimage, Ewald Hering, opponent color theory, cones, over stimulated, spectrum, complementary, color vision, retina, palinopsia, positive afterimage, and optical illusion.
http://en.wikipedia.org/wiki/Afterimage
http://www.palinopsiafoundation.org/about-palinopsia/
http://library.thinkquest.org/27066/theeye/nlsuccontrast.html
Interesting. I was unaware of palinopsia. Good to know.
After reading the chapter I became interested in additive color mixture. This was a topic that caught my attention because it is kind of the opposite of what we usually think of. Like the book said it's completely different color mixture than what we learn in elementary school (which would be more like subtractive color mixture). Additive color mixture would be if you were to add red to green you would get yellow, but subtractive color mixture would be if you were to add yellow to blue you would get green. In subtractive color mixture if you were to add red to green you would more than likely get a brown, so this can be a bit confusing.
Additive color mixture is mostly used in computers and televisions because additive color mixture shows up when the color is emitted through a light source. The reason why we see additive color is because our retina uses our cones when we see these wavelengths of color. The cones that are used to see these different wavelengths are the L, M, S cones, each are stimulated by different wavelengths. As we discussed in class we are not really seeing colors with our eyes we are seeing wavelengths and our brain perceives this as color. Our primary colors come from our L, M, and S comes, those colors are red, green and blue. If we were to adjust the brightness of the primary colors the mixes would be different, this is why we can see so many different colors on the television or the computer.
While I was researching the topic I found additive color mixture was discovered by scientists. One of the main scientists was James Clerk Maxwell. Maxwell wanted people to know that our primary colors perceived were red, green and blue not red, yellow and blue. He discovered additive color mixture from the trilinear mixing triangle. The three main colors emitted in the triangle are red, green, and blue (this is usually the main example given to illustrate additive color mixture). When all of the colors overlap they make white. Also in this trilinear mixing triangle chromaticity is used, this is the saturation and hue of the color. Just like brightness when the hue and saturation are adjusted in the red, green and blue the colors that produced by the combinations will be different. Also along with Maxwell discovering the additive color mixture he discovered the basics of colored photography.
Terms: additive color mixture, subtractive color mixture, L cones, S cones, M cones, cones, retina, brightness, saturation, hue, chromaticity
http://en.wikipedia.org/wiki/Additive_color
http://www.handprint.com/HP/WCL/color5.html
http://www.greatreality.com/ColorAdd.htm
Pretty interesting stuff. I was amazing about the different types of color mixing as well when I first heard about it.
After Reading chapter 5, I found the section on “does everyone see colors the same way?” to be my favorite of the material I read. My main interests out of this section were deuteranopes, protanopes, and tritanopes. The book defines deuteranopes as people lacking M-cones, protanopes as people lacking L-cones, and tritanopes as people lacking S-cones. The book didn’t really go into detail on what it would be like to have such an abnormality, so I thought it would be interesting to research what one sees if they have a certain cone missing. I believe this fits in with our book and class because many people have to deal with color blindness in our world. It’s important to understand what people with color blindness have to go through on a day to day basis compared to what a normal person goes through.
When I started looking up information on the topics, I noticed that for most people, color blindness is hereditary. The cause of M-cone and L-cone color blindness comes from the X-chromosome. In most cases there’s a problem in gene coding in the X chromosome that doesn’t include the L or M-cone information. This is why many more men have color blindness than women, since men only have one X chromosome compared to women, who have two. Tritanopes, on the other hand, are not sex related chromosomes, so men and women have equal chances of having this type of color blindness. Something I found equally of interest is that people who have tritanope color blindness can acquire it through other ways besides inheriting it. Injuries to the head, consumption of alcohol, aging can all lead to tritanope color blindness.
The most common form of color blindness is deuteranope; which affects 6 percent of all of the male population. This is when a person lacks M-cones in their vision. The main colors that are affected in deuteranopes (are red and green but it also can have an effect on gray, purple, and blue greenish colors. The main color in effected in deuteranopes is green. They had pictures of what it would be like if you had deuteranope colorblindness on this website I visited. I feel like it would be very challenging to have this type in the world we live in because we rely on the green and red colors so much.
Protanope is another form of Red-Green Color Blindness which again affects the L-cones. Prontanopes have troubles distinguishing between blue and green and red and green colors. They are blind to a lot more colors than the Deuternopes, so they aren’t really categorized just under Red-green blindness. Luckily, this affects a much smaller portion of the male population with only 1 percent. From the color they showed on the website, it looked like Protanopes have very little color vision at all when compared to the color chart of a normal person. I’m assuming that most vision from a Protanope is in grayscale, which would make everyday life a nightmare in my opinion.
The last type of cone color blindness is Tritanopia. This occurs when a person has no S-cones. This type of color blindness affects a person’s blue-yellow colors. Often people with tritanopia confuse blue with will green and yellow with violet. The chances of getting tritanopia are much lower than (1 out of 10,000) than the other two color blindness deficiencies. This type of color blindness, while bad, has less of an impact than Red-green color blindness. One of the articles pointed out how our society relies on green and red so much more in the world (Ex. Stop lights) that it’s easier to get by for a tritanope.
I can’t imagine which type of color blindness would be worse to have. I know it’s very easy for people to adapt live just as successful lives but I think it would suck to not be able to see all the colors that are out there. It could be worse though, I can’t imagine being Rod Monochromatic and having terrible day vision with only gray scale abilities. I think if I took something away from what I read, it’s that this world is full of color coding and we rely on our vision a lot more than we think. It makes me think of what a world with no color would be like. Would everything be labeled with instructions instead of a universal color like it is now? It would definitely be a different world than what we live in now.
Terms: Deuteranope, protanope, tritanope, color blindness, rod monochromatic, rod, cone, S-cone, L-cone, M-cone.
http://www.colblindor.com/2006/05/08/tritanopia-blue-yellow-color-blindness/
http://en.wikipedia.org/wiki/Monochromacy
http://en.wikipedia.org/wiki/Color_blindness#Epidemiology
http://www.colblindor.com/2006/11/16/protanopia-red-green-color-blindness/
http://www.colblindor.com/2007/04/17/deuteranopia-red-green-color-blindness/
I've also heard that degeneration of s-cones can occur via diabetes which can be detected in a clinical VEP (visual evoked potential) using EEG. Pretty interesting deficiencies that can arise in human color vision.
Color blindness is defined at the inability to perceive color differences. This happens when there is damage or developmental problems with the cones in the retina. The retina is the light sensitive area in the back of the eye that contains photoreceptors. There are two kinds of photoreceptors: cones, which are sensitive to light, and rods, which are useful in low-lit circumstances. Cones are the photoreceptors that sense color; more specifically they detect visible light. There are three kinds of cones that are separated depending on the wavelength of the visible light. The three different kinds of cones are short cones (S cones), Medium cones (M cones), and Long cones (L cones). These cones detect wavelengths at their highest sensitivity points, which is where the color perception comes from. In the visible color spectrum, these sensitivity points are blue, yellow, and yellow/green, which means that these are the first colors that the eye perceives. In summary, when different cones sense different wavelength, they become stimulated and overlap with other cones. This combination becomes the tangible colors that we experience daily.
Essentially, there are three different kinds of color blindness, or color deficiency. The most common case is when one cone is either missing or damaged. Those who have deficiency in this cone have trouble with reds and greens. This does not necessarily mean that they cannot see these colors, but rather the differences between these colors (and other similar colors) can be hard to determine. Another type of color blindness is when a different cone is missing. When this happens, people don’t only have troubles with reds and greens, but they also struggle to see blues and yellows. The missing cone affects how the cones combine to make colors, without the cone, the colors do not overlap. The final and most severe type is called achromatopsia. Achromatopsia is a rare form of color blindness in which sufferers do not perceive color. They instead view the world in hues of gray. There are also other visual complications such as light sensitivity and poor vision. Color blindness is genetic disorder that is more common in males than females.
I chose to speak of color blindness because it was a disorder that I had always heard of but that I did not have much information about. I assumed that there was only one kind of color blindness in which people only saw things in black and white. I was surprised to find that color blindness really isn’t as severe as I always thought it was. In fact, people with this deficiency live quite normal lives, with the exception of limitations in certain professions. This relates with the class because the causes of color blindness are found in the photoreceptors, which is a common theme in the book thus far.
Terms: Color blindness, cones, rods, retina, photoreceptors, achromatopsia, s cones, m cones, l cones, color spectrum, visible light, and wavelengths.
http://en.wikipedia.org/wiki/Color_blindness
http://www.webmd.com/eye-health/tc/color-blindness-topic-overview
http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001997/
Check out Island of the Colorblind (a book) by neurologist and author Oliver Sacks. I think if you're interested in colorblindness especially the prevalence with which this can occur genetically.
My main topic was color vision in animals. This relates to the chapter because once you know what color is, you can started to look at the environment from a different view. Human S-cones, M-cones, and L-cones react to wavelengths helping us to see color and understand and make sense of our environment. But many researchers have asked if animals see the world like we do. We can’t ask a dog, cat, or another animal what it sees so scientists have to come up with ways of trying to find out what different animals see.
I think one of the most interesting thing I found through my research was how wrong a lot of theories about animal vision used to be. I remember being told that animals see the world in black and white and that sharks are practically blind and attack people because they often make the mistake of thinking people are turtles or seals. The truth is, mammals have some of the weakest color vision. Although primates and humans have advanced color perception, we still see less than what other animals see. Snakes have infrared vision, not really surprising though considering science has known that they seek out heat as their pray. Birds and fish have very sensitive photoreceptors. It makes sense for birds since they have to be able to accurately identify their pray from long distances, but knowing fish can too was a little surprising. Sharks have been labeled as almost blind for decades, before there was actual science, equipment, and understand about vision to prove this wrong. It is a fact that sharks have enhanced electrosensory capabilities, but their eye sight is still in question when it comes to certain species. Hammerheads are the target for many of these questions. Even though they have eyes on the sides of their heads, scientists have been able to discover that they actually have complete 360 degree vertical vision. Along with rearview binocular vision (binocular vision: vision that over-laps in the middle to give depth perception). I mentioned in the beginning that animal vision was my main topic, my side topic was additive and subtractive color mixing. I was able to find an illustration (animation) better depicting a color cube.
http://www.colorbasics.com/AdditiveSubtractiveColors/
http://www.webexhibits.org/causesofcolor/17.html
http://news.discovery.com/animals/hammerhead-sharks-stereo-vision.html
Terms: color vision, S-cones, M-cones, L-cones, wavelengths, advanced color perception, infrared vision, photoreceptors, enhanced electrosensory capabilities, depth perception, additive color mixing, and subtractive color mixing.
Interesting post. I took a comparative neurophysiology course at UNR and we discussed the mantis shrimp. It's visual system, let alone color vision, is so complex I'm fairly sure even the experts on the mantis don't really understand completely how it works. Also, there are all these e-vectors and m-vectors that are detectable by some animal species (bees and birds I think) that allow them to perceive planes of polarization, which is something we don't really think about with respect to human vision. Also, it has been hypothesized that magnetite crystalline structures within the neurons of some species of giant sea turtles allow them to navigate in the ocean based on the magnetic fields of the planet (used roughly as a lat/longitude marker). Just an amazing amount of things that we don't have direct phenomenological access to as human beings.
I found an extremely interesting website that I couldn’t stop reading. Did you know that the human eye can see around 7 million different colors? While researching more information about what exactly an After Image is, I found a website that helps better explain what colors mean to us. An afterimage is a visual image seen after the stimulus has been removed. I found the concept of an after image to be so fascinating because to me it’s almost like an optical illusion or is if your brain is playing a trick on you. If you were to view an image for a couple of minutes that have a certain color on it, then look away, then the opposite color of the original color should then appear. The very first original color that was being viewed is considered an adapting stimulus. The illusory color that is being viewed after seeing the adapting stimulus is known as the negative afterimage. Our eyes are filled with around 250,000 color decoding cones that help interpret our colors. What happens when we view an after image is some of those 250,000 cones become fatigue and no longer is able to view that certain color.
What color do you think is the most irritating? If you guessed the color yellow (bright lemon), than you are correct. This is caused by the physics of light and our visual system. Bright lemon yellow is the first and easiest color we see when looking at the full spectrum of color. The brightness, which is the distance from black in color space, also helps judge if a color is irritating. For example, a bright lemon yellow compared to soft buttercup yellow may be viewed as one is calm and the other is loud. I also learned that chickens may become more calm, produce more eggs and fight less when they wear red glasses. The saturation of the glasses must be full red, because any other hue of the color would not work.
Term: Afterimage, adapting stimulus, illusory color, negative afterimage, decoding cones, physics of light, visual system, brightness, saturation, hue.
http://www.colormatters.com/color-and-vision/color-and-vision-matters
http://en.wikipedia.org/wiki/Afterimage
http://www.exploratorium.edu/snacks/afterimage/index.html
There is also some interesting stuff out there about visual discomfort via certain spatial frequencies. I think that certain colors can be displeasing to the eyes as well. Interesting.
This week I wanted to focus on color perception as it relates to culture. I discovered a study that calls the work of Berlin and Kay from the book into question, but I do not believe either research is completely definitive, and therefore that perceptual experiences of color lie somewhere between the two.
Thierry et al. use an EEG to measure electrical brain activity while participants are exposed to a series of stimuli, a procedure also known as monitoring event-related potential (ERP). In their experiment, native English and Greek speakers were shown mostly colored circles with intermittently placed colored squares. The linguistic distinction is important because English does not have separate words for light and dark blue, but Greek does: ghalazio and ble. Participants were instructed to press a button whenever they saw a square shape, but EEG patterns were focused upon brainwave fluctuations in response to changes in color. The research team claims that the brain’s reponse to novel stimuli is preattentive and unconscious, which means that any fluctuations in perceptual discrimination may be attributable to the existence or lack of dichotomous color terms in one’s native language. Their results indicate that language differences are indeed correlated with color perception. This may mean that the terminology of a person’s native language may indeed have an unconscious effect on the early stages of color perception!
This research lends further credibility to the work of Debi Roberson from our book and demonstrates that color perception is not strictly relativistic. Berlin and Kay’s work from the book cannot be completely ignored either, as several studies (including that of Lindsay & Brown) have analyzed data from the World Color Survey and shown that there are definitely universally-held propensities for naming colors across all languages. This work also restricts the traditional Whorfian view that color terminology can vary greatly by language, because we may share a common innate representation of color space, as indicated in the work of Regier, Kay and & Khertepal.
Terms: EEG, ERP, relativism, universalism, Whorfian hypothesis, color space
http://www.pnas.org/content/106/11/4567.full.pdf+html
http://www.icsi.berkeley.edu/~kay/WFness.pdf
http://www.pnas.org/content/103/44/16608.full.pdf+html
Very interesting post. The world color survey stuff is awesome and I've seen people give talks about their work on the cultural aspects of color. Nice work.
It was hard for me to decide on a specific topic to look up since I found this chapter to all be interesting. But with the final decision, which was chosen from enie-menie-minie-mo, I decided to research more on if people all see colors in the same way. Everything we discussed about color perception was interesting.
As we learned, the way we see color is based on the three color photoreceptors and visible light. Some people are missing a rod, which leads to color blindness. Some people who do not have color blindness, but have synesthesia, which is where you can see colors within letters, words, shapes or sounds but when it come to cordinating an outfit you have "no sense of color".
David Williams did research with an experiment on this topic. His findings were that since we all share the same world, then we all see colors the same. He noticed that the middle and long wavelength cones seemd to be scattered all throughout the retina, but yet people were still claiming to see the same kind of yellow. So basically, our color vision is based on our perception on the world.
Terms: color perception, color photoreceptors, visible light, synesthesia, middle wavelength cone, long wavelength cone, retina
http://www.quora.com/Is-everyones-experience-of-color-the-same
http://www.sciencedaily.com/releases/2005/10/051026082313.htm
http://www.sciencedaily.com/releases/2005/10/051026082313.htm
synesthesia is definately an interesting topic for perception.
I wanted to learn more about color vision in animals. I wanted to know more about this because it is more important to animals than it is to humans. Humans have come up with ways to function without being able to see color or be able to see at all. However, color for animals is directly linked to their individual survival.
Mammals closely related to humans see color as we do because they are trichromates. They have the L,S, and M cones. Dogs, cats, mice, rabbits and most other mammals are dichromates and only see limited colors. This means that they only have to cone receptors and cannot see color as we do. Mammals such as the bull are completely color blind. Bulls charge a red cape because it is waving, not because it is red. Insects typically have very good color receptors. Bees and butterfly's can even see ultraviolet color. This helps guide them to specific flowers. Bees also have color vision that is 5 times faster than humans. Their color vision is the fastest yet clocked. Flies have the fastest vision yet clocked. Some birds have tetracromacy (4 cone receptors.) Some animals such as the mantis shrimp have 12 different color receptors. Other animals such as the pit viper do not need to see at all. They rely only on heat sensors for survival. I think that it is really amazing how evolution has specialized different animal species for their necessary survival needs.
Terms: trichromates, dichromates,L cone, S cone, M cone, tetracromate
http://en.wikipedia.org/wiki/Color_vision#In_other_animal_species
http://news.discovery.com/animals/bumblebee-color-vision.html
http://www.colormatters.com/color-matters-for-kids/how-animals-see-color
This link will show you how you would see if you were different animals.
http://en.wikipedia.org/wiki/Color_vision#In_other_animal_species
In choosing a topic to write about, I chose the forms of anomia and agnosia as it is very complex and unimaginable to relate to or to understand. These inabilities or failures are related to brain lesions or brain damages.
Visual object agnosia is when a patient is alert, intelligent, able to see an object, but is unable to know or identify or recognize what the object is. This perceptual disorder does not allow patients to recognize what they are seeing, hearing or feeling. This is usually a result of lesions or damages to the brain that have disconnected the visual and audio perceptions. Fortunately this is rare, with less than one percent of neurological patients having agnosia.
There are two categories of agnosia—apperceptive visual agnosia and associative visual agnosia. Apperceptive visual agnosia includes visual ability, but the inability to access or process what is seen. A stroke victim or carbon monoxide poisoning can be causes with this inability, due to their processing level deficiencies. The damage is early on in the recognition process. Associative visual agnosia is when a patient can see objects; but is not able to relate the meaning of the object or word. The damage is in the later stages of recognition, where memory may not be in tact. This can result from tumors, hemorrhage or nerve damages to the brain. It is more common than apperceptive visual agnosia.
Anomia is a condition that includes the inability to name objects, colors or people—even though they can see and recognize them. Anomia is a type of aphasia, disorder caused by brain damage to the parts of the brain that controls communications. This is usually a result of tumors, head injuries, strokes or an infection in the brain (left side of the brain that controls communication functions). Anomia is part of the non-fluent aphasis category. A person may speak with hesitation due to the uncertainty in trying to communicate. Speech therapy is often used in the rehabilitation process.
Agnosia and anomia seems to me like it is most closely related to stoke victims and their recovery processes. You see this happen most often. There is a constant struggle in recognition and communication with visually trying to comprehend and recognize objects, people and more. In trying to imagine what they are going through would almost have to be like a bad dream where you know what you want to say, but it never comes out, or you are trying to run somewhere and you just don’t seem to move.
Terms: agnosia, anomia, apperceptive visual agnosia, associative visual agnosia, aphasia, non-fluent aphasias
http://www.acnr.co.uk/pdfs/volume4issue5/v4i5cognitive.pdf
http://cueflash.com/decks/Agnosia
http://www.healthline.com/galecontent/anomia
Topical blog #6
After reading the chapter I wanted to explore more on the topic of visual perception of figure and ground. I found this to be interesting because we focus on an object and not the background or vise-versa. The perfect example of this would be the Rubin vase-face test that is a white vase with a back background, or two faces to the side with a white or clear background. This is also interesting because many people take for granted the little things around them.
The first website I found shows the Gestalt principles of visual perception. Gestalt had psychologists that worked on visual images and shapes from a particular background. The figure and ground concept is very important when one understands perception and organisms. Proximity is important to the visual objects because it determines our focus on objects and how far apart they are around us. Similarity is another part of Gestalts principles that show objects that look similar to each other such as dots and another object of dots and squares; they look similar but are different! The smallness of an object is determined by the background which shows if the object is large or small. Symmetry is another process that shows an object is able to be closed together, would it fit perfectly? Yes. Everyone uses Gestalts process of visual perception to view objects around us in every day life. It is important to not take for granted the little things and observe all parts of an image or object.
http://www.artinarch.com/vp12.html
The second website I found shows Gestalts principles of objects and ground by showing different objects that look like another object because of the background. The video showed a lemon that looked like it had a human face imbedded inside of the fruit. The second image was showing the view from a plane looking down at land that looked like the Nazi symbol. Many individuals ignore and cannot perceive things that are “hiding” from the background. Overlooking objects and other objects inside of objects is common because the visual perception wants to see just the one object. Our perception is to know see one object, and sometimes it takes more practice and time to observe these images to get the “full picture.” Search figure and ground on google, and many images and activities show up to see what you perceive from an object and its background!
http://www.youtube.com/watch?v=nxKcpfFvuf8
The third article I found was a lab from the Duke University explaining in detail the process of perceptual segregation in everyday life. The report states that when a person uses the perceptual segregation, it usually comes naturally when we are observing and understanding our environment around us. Our attention is focused on an object and organizes what it looks like, and knowing what that object does. Gestalt has a law of grouping which shows how elements are grouped in a scene in the environment. The visual space around us either captures our full attention at one part of the environment and we ignore the other textures or features of the visual image. Attention is a fundamental problem when noticing an object or an image, and we use attention to be aware of these things. Our segregation can ignore or focus on certain colors and motions that attract more attention and is effortless to perceive. On the other hand, when we see 3D visual images this is beyond our vision, because when we talk to people in a crowded place, we can focus on what they are saying and hear the other people around us being loud. It is very interesting knowing that our brain signals and notices only what it needs to or wants to that is in our pathway. This report was useful to read because I got a better understanding of the process of perceptual segregation.
http://woldorfflab.ccn.duke.edu/files/uimages/Perceptual_Segregation-FINAL.pdf
vocab= perceptual segregation, attention, visual space, textures, Gestalt, proximity, smallness, symmetry, similarity
This week I decided to look more into different color disorders mentioned in the book. As I had said before, I didn't know that half of these disorders existed. I thought that the only difference in seeing colors amongst people was color blindness. I hope to gain more information while looking at this topic!
When looking through the American Optometric Association website, I learned that color blindness is what most people refer to each disorder, but that is not what they are all called. I learned that when someone is totally color blind, it is called achromatopsia which is the only term that truly should be associated with total color blindness. I also found it interesting that people who are color-blind in both eyes have inherited that trait and those who have lost color vision in only one eye have had some type of injury or illness causing the disorder.
http://www.aoa.org/patients-and-public/eye-and-vision-problems/glossary-of-eye-and-vision-conditions/color-deficiency?sso=y
The Genetics Home Reference website gave me some other insights into color vision deficiency. They classify the many different forms of color-blindness as a group of conditions that make color-blindness. This made more sense to me than the way the book explained it because I was confused by the fact that they are all considered "color-blind" to the public's eye but they aren't all color-blind per say. I had known previously that people can mix up certain colors but I never knew that most people with this disorder only mess up red and green. Through this website, I also learned that men are way more likely to get this disorder than women with a ratio of 1 to 16.
http://ghr.nlm.nih.gov/condition/color-vision-deficiency
I was curious as to what people with color vision deficiency see when they perceive the world, so I decided to look at Google images to see some of these charts. This really helped me to understand the difference in most of these disorders by distinguishing them by color. One of the charts I looked at showed the difference between protanope (cannot see red), deuteranope (unable to see red and green) and tritanope (cannot see blue). It was cool to see what people with these specific types see on their own personal color spectrum.
https://www.google.com/search?q=color+vision+deficiency&client=firefox-a&rls=org.mozilla:en-US:official&channel=sb&source=lnms&tbm=isch&sa=X&ei=BMfGU9SlKMeNyASy1YF4&ved=0CAYQ_AUoAQ&biw=1280&bih=672