Topical Blog Week #6 (Due Wednesday)

My topic this week is about the two primary theories of colour perception. This topic is closely connected to the chapter, which discusses what happens when the eyes perceive colours (or different physical wavelength. I am interested in this topic because upon reading the chapter and the research, I wonder which theory is more dominant in explaining colour perception.

THEORIES OF COLOUR PERCEPTION

Why do we see colours differently than other species? Why is there a slight different between the colour perceptions of each individual human? It is hard to believe that the colours we see every day is merely an interaction between the physical properties of our eyes and the external physical stimuli, but it is also “the” interaction between the our visual system and the external stimuli! It sounds just as simple and just as complicated as it sounds. Different theories was developed to explain why we see what we see, and I am discussing the two main theories in this blog post: trichromatic theory and the opponent process theory.

Both trichromatic theory and the opponent process theory aim to discuss how we see colour, or how the interaction between the physical properties of light and our perception of colour in respect to our nervous system. Each theory has its flaws and advantages, and there are plenty of research which can provide ample support for both theories. We will have to judge which one we can go with.

The trichromatic theory, also known as the three colour theory, was first proposed by Thomas Young in the early 19th century, and modified by Hermann von Helmholtz half a century later; therefore it can also be known as the Young Helmholtz theory. The idea of this theory is basically colour matching. The fundamental element of this theory is that our visual system sees three colours, and the further mixing of these three primary colours essentially creates the rest of the colours we see. The three primary colours are red, green, and blue.

The physical structure of our eyes suggest that this theory is can be true. There are three types of colour detecting cones in the retina, and each types of cones can detect different wavelengths. One can detect longer wavelengths that show red, one is sensitive to medium wavelengths that appear green, and the last set of cones reacts to short wavelengths such as blue. These cones are L (long wavelengths), M (medium wavelengths), and S (short wavelengths) cones, respectively.

Besides the anatomy of the eyes, the colour matching experiment Young and Helmholtz developed also supported the theory. The researchers show a primary colour to the participants, who were then asked to adjust the intensities of the mixture of two colours together until the mixture appear as close to the primary colour as possible. Although the mixture colour can never become identical to the primary colour, because of the substantially different physical components, but the participants can make them “appear” identical.

However, this theory cannot explain some of the perception phenomenon, such as after images of colours. Try staring at a red dot for a while before looking at a white wall, where you will see a green dot. Same thing can happen to yellow and blue. Try staring at a blue dot before looking at a white wall, what do you see?

Based upon the after images, Ewald Hering proposed the proponent process theory in the late 19th century. The theory has two basic ideas, colour opponency and adapting. Colour opponency suggests that the colour sensitive cones work together to form three pairs of opposing colours: black and white, blue and yellow, and red and green. Colour perception is thought to occur within these three channels by competing with the opposing colours. For example, when staring at a red dot for so long, the red-sensitive cones get worn out, and the blue-sensitive cones wins over when you move your fixation onto a white wall, and that green dot you see is the after image. Adapting suggests that the interaction between the cones’ coordination of light and the central visual system does not produce fixed colour, which changes under different context where the lights are viewed.

However, this theory seems odd when we think of the colour yellow. There is no yellow-sensitive cones. Yellow is essentially explained with the interactions between red and green wavelengths. When the brain detects more blue activities hitting the retina, we see blue; when the brain detects more activities of the combination or red and green wavelengths hitting the retina, we see yellow. How this theory works is basically how we mix different water colours in grade school – remember how you were amazed with how yellow pops up after you mix green and red together?

Some further research has shown supports for this theory. In the mid-20th century, an experiment consists of electrical recordings from the LGN shows that it is where colour perception takes place – the LGN from the brain. Further studies using modern technology also provide proof that bipolar and ganglion cells are involved in colour perception; the bipolar cells convert information received from the cones, the pass all the information to the ganglion cells where a bunch of colours are being handled. This process is an important part of the opponent process theories.

Both theories have empirical scientific support, but both fail to explain colour constancy. These two theories complement each other, and can be combined to explain how our visual system actually works. The Young Helmholtz theory explains the basis of the physiological reaction to different wavelengths that hit our eyes, and the opposing process theory explains the neurological processing of those physiological information. None can be accounted more than the other.

TERMS: neurological, physical, visual system, LGN, ganglion cells, bipolar cells, cones, wavelengths, trichromatic theory, opposing process theory, colour matching, colour constancy, after images, adapting, colour opponency

http://www.ukessays.co.uk/essays/psychology/theories-of-vision.php

This is a well written essay explaining the basic elements of both t
heories, as well as providing the comparison between the two. I was able to understand a longer research paper after reading this essay, which was the most beneficial website regarding this blog post.

http://color.psych.upenn.edu/brainard/papers/ColorTheory1.pdf

This is a research paper on both theories, where mathematic formulas were involves. I scanned through the paper. It was hard to understand but it provided me with empirical evidence that supports both theories, which I thought was very beneficial as it helped me more in my understanding of how the theories were supported.

http://psych.ucalgary.ca/PACE/VA-Lab/colourperceptionweb/theories.htm

This article was not at all that useful since it provided me with minimal information regarding colour perception, but it was helpful in a sense that it makes the basic components of the two theories a lot easier to understand.

I chose to research the topic of color blindness and color vision in animals. This was briefly discussed in the chapter but a lot about the different amount of cones and wavelengths that animas are able to see is also discussed and related to the chapter. I choose to research this because I thought it would be interesting, and I always wondered if animals see things the way that we do, or if they see differently.

To begin with, animals are typically tested for color vision by the placement of multiple panels with various colors. Two of the panels are typically the same and the third is different. If they are able to identify the panel that has the varied color, they are rewarded. The panels are then switched up to see if they can still identify the correct color. However, a study was done for goldfish where they had to swim to a correct panel in order to receive the treat. Light intensity and color was changed to see if it would affect their ability to identify the correctly colored panel and it was found that it did not.

Color blindness typically occurs on the X chromosome and is recessive. This means that females get it less because if one X chromosome is healthy then the disease is not present. It also means that men cannot pass color blindness to their sons, because they only pass on their Y chromosome. Most animals are at least partially color blind, but often times the colors animals see are for evolutionary purposes.

Next the different visual systems of several animals were discussed. Insects were discussed several times, mainly bees. Like humans bees have a trichromatic visual system (3 cone classes), but see yellow/blue/ultraviolet instead of red/green/blue. Their eyes also have multiple lenses, which results in low resolution. An interesting fact mentioned was that if we had multiple lenses and kept our resolution, as humans, our eyes would be as big as hula-hoops. Insects are also thought to have more complex eyes because their processing occurs in the eye instead of like the brain as in humans. Butterflies can also see ultraviolet markings in flowers (like bees), but can also identify ultraviolet markings on other butterflies that help them identify each other. Humans cannot usually see these markings, unless they are also iridescent.

Cats are dichromate (2 cones) and are very similar to humans with red-green color blindness. They are thought to have daytime vision that is 6 times worse than humans, and due to a larger amount of rods than cones, night vision that is 6 times better than humans.

Birds are tetrachromats (4 cones) and can see green/red/blue/ultraviolet, and sometimes have better resolution than humans. The ultraviolet helps them identify some animals with ultraviolet markings. They also can see underwater while moving unlike humans. Pigeons are thought to be able to see as many as 5 spectral bands of color and are very good at identifying the difference between colors that resemble each other closely.

Rattlesnakes are unique like other snakes they have a special neural receptor that is able to transform infrared light into neural signals. Interestingly enough, humans have the same neural receptor but ours sends signals of pain after eating spicy foods, instead of interpreting infrared heat signatures. Snakes combine their very low-resolution visual images with the infrared image to create their image of vision.

Cuttlefish were also discussed as being completely unique from vertebrates. They have no blind spot and their pupils are shaped like W’s instead of O’s. They are completely colorblind but have one photoreceptor that allows them to see grey. They are however, able to see polarization, which they use to communicate with other fish.

Terms: color blindness in animals, cones, rods, wavelengths, trichromatic, dichromate, tetrachromats, resolution, ultraviolet, light intensity, color, vision, spectral bands of color, neural receptor, resolution, infrared, photoreceptor, polarization, blind spot

http://nautil.us/issue/11/light/how-animals-see-the-world
I used this website because it included slides that allowed you to see the difference between animal and human vision. It covered a lot of animal’s visions and contributed a lot to my post.

http://www.nytimes.com/1985/08/13/science/vision-through-animal-eyes-reveals-surprising-color.html?pagewanted=2
This website was useful because it talked about how animals are tested for color blindness, as well as basic terminology that was discussed in the book, but it helped me better understand the vocab. It discussed specific experiments done on animals, so it also contributed a lot.

http://www.webexhibits.org/causesofcolor/17C.html
This website was reviewing a lot from the other websites I had visited but added information on insects and butterflies that I hadn’t read before as well as other animals. It contributed the least but was still very informative.

1a. I chose to focus on the visual system and different ways it influences our perception of color regarding the human face, connotations of color, and mate selection in the animal kingdom. I decided to give myself a broad spectrum of research to look at because I wanted to exemplify the idea that perception of color effects every aspect of life and the evolutionary process.
1b. This topic relates to chapter five because it provides context and research studies that demonstrate the importance of our perception of color and the importance of color perception in the animal kingdom. It covers the parts of the visual system associated with perceiving color and studies that provide strong evidence for the effects that color and shading have on our perception and for what our brain finds pleasurable.
1c. I am interested in this topic because it relates to every aspect of what we experience on a daily basis. We are constantly bombarded with physical properties that our brain perceives to have color and shading. The perception facilitated by our brain influences our attraction, our dislike, and our perception of an entire environmental or social situation. Additionally I am interested in how this perception affects the animal kingdom and their mate selection. I think it is worthwhile to discover the extent to which animals perceive objects and color the way we do. I enjoy researching topics like this because it has real world applications and has an affect on so much more than we realize.
2. The first article by Nakajima et al. found that our perception of facial color is vitally important for correctly perceiving the emotion and general health of another person while communicating. When we are correctly able to perceive the emotions of another person a neuron specific for facial recognition fires and allows us to interact in a socially acceptable way. This is relevant because it would be maladaptive to be unable to correctly perceive emotion. In a social context it would cause exclusion if we responded to a persons sad expression with joy and happiness. The ability to be empathetic and to interact healthily with our social groups is heavily influenced by our brains perception of the color and shading of the face. I found this very interesting because I have not often thought about the process my brain goes through when it is interpreting the facial expressions and emotions of someone else. We are typically able to perceive these traits or expressions in a matter of seconds and without much thought. It is incredible to realize that our brains ability to perceive color is directly related to our social interactions with people and our ability to read their emotions accurately. A second article by Sorokowski et al. explored the idea that the color of a sports uniform actually effects sports performance as a result of our brains perception of the color. The researchers found that there is a cross cultural finding that supports cultural relativism and the idea that that the colors red and black are associated with winning. Athletes wearing a different color during a sport that involves competition between two or more players were perceptually found to be weaker and less likely to win, even if that perception was overtly wrong. This finding suggests that color plays an important role in our perception of inferiority in the context of sports. I find this endlessly interesting and have so many questions regarding this finding. It is amazing that colors such as black and red that often indicate negative emotions or situations are perceived as more likely to win when worn by an athlete. One could hypothesize that the use of red and black for traffic lights and clothing worn by important people could result in the colors being associated with power. I found this article to be very relevant to the our perception of color and the effects it has on our daily lives. Lastly, an article by Hughes et al. also demonstrated the importance of certain colors on the perception of monkeys and their mate selections. Generally, humans and animals find possible mates more attractive when they are associated with the color red. To test these findings researchers presented monkeys in their sample with pictures of the rear ends of the opposite sex with different color backgrounds. The results showed that female monkeys were more attracted to the image that was presented with a colorful (red) background. This finding is interesting because it demonstrates the importance of our perception in color. It follows the same concept of the jersey research study because it shows that certain colors are associated with dominance and specifically a fit mate. I think it is incredible that something as small as our perception of the color the opposite sex is wearing can have an effect on our perception of their attractiveness. All of these findings are thought provoking and provide applicable research to understand our perception of color.
Terms: visual system, color perception, perception, sensory, cultural relativism

http://web.b.ebscohost.com.proxy.lib.uni.edu/ehost/detail/detail?vid=6&sid=1301bea3-ba7e-4c02-9e4c-c46b097ed143%40sessionmgr112&hid=109&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=psyh&AN=2014-40934-001 I chose this article because it showed strong evidence for the idea that color perception influences mate choices in animals and also humans.

http://web.b.ebscohost.com.proxy.lib.uni.edu/ehost/detail/detail?vid=7&sid=23aea01e-51d0-4c5e-9941-72e727b5826e%40sessionmgr198&hid=109&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=psyh&AN=2014-44350-008 I chose this article because it supported the finding that our perception of color influences our interpretation of events, specifically sporting events in this study. It also supports the idea that we innately associate some colors with power and success, and others with weakness inferiority.

http://web.b.ebscohost.com.proxy.lib.uni.edu/ehost/detail/detail?vid=15&sid=b3320392-0d0b-4d0a-ba84-f7f9b423af5a%40sessionmgr110&hid=109&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=psyh&AN=2014-17814-001 I chose this article because it found strong evidence for color perception being an important part of our daily social interactions by allowing us to determine the emotional and physical state of a person.

1a) State what your topic is: Achromatopsia

1b) Discuss how the topic relates to the chapter.

This is directly related to chapter 5 as it is explained on page 133 of our textbook. Achromatopsia is the inability to perceive colors that is caused by damage to the central nervous system.

1c) Discuss why you are interested in it.
Honestly, no one in my family has this, nor have I ever met anyone with this, so I was most intrigued by the subject and how a person is affected by not seeing color. Our world is filled with many ways we use color as a means of communication and I wondered how people were affected by not seeing color. I was also curious on whether or not this could be treated, corrected and if so, how could someone just live with never seeing color.

I also wanted to find out if this was hereditary.

After researching the subject of Achromatopsia I found that there are two types of achromatopsia: congenital achromatopsia and cerebral achromatopsia.
Achromatopsia (congenial) is a non-progressive and hereditary visual disorder which is characterized by decreased vision, light sensitivity, and the absence of color vision. People with complete achromatopsia cannot perceive any colors; they see only black, white, and shades of gray. (There is also incomplete achromatopsia which is a milder form of the condition that allows some color discrimination.)

Getting further into the subject of achromatopsia, it is also known as a disorder of the retina. The retina contains two types of light receptor cells, called rods and cones. These cells transmit visual signals from the eye to the brain through a process called phototransduction. Rods provide vision in low light (night vision). Cones provide vision in bright light (daylight vision), including color vision.

It is considered rare, as statistics show that one in every 33,000 - 40,000 people are affected. The numbers vary in different parts of the world. From my research, due to the genetic link, it is more common in regions where there is a high rate of consanguineous marriages (marriages between relatives), the eastern Pacific islands, the Pingelapese islanders (they live on one of the Eastern Caroline Islands of Micronesia). It is said that between 4 and 10 percent of people in this population have a total absence of color vision. (WOW!)

Another fact I found during my research is that it happens right at conception. Each sibling of an affected individual has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Carrier testing for at-risk family members and prenatal testing for pregnancies at increased risk are possible once the disease-causing mutations have been identified in the family.

The second type of achromatopsia which should never be confused with congential is cerebral achromatopsia, also known as the acquired form of total colorblindness that can result from trauma, illness, or some other cause. People who develop cerebral achromatopsia report that they see a monochromatic world, all in shades of gray. They are able to see gray because they previously experienced color vision, making it possible for them to perceive the absence of color as gray. This is in sharp contrast to the visual perception of congenital, complete achromats (complete rod monochromats), who report that the concept of "gray" is as mystifying to them as is the concept of any of the other colors. People with cerebral achromatopsia are diagnosed by neurologists, rather than eye specialists. Their loss of color perception is not accompanied by severely impaired vision, extreme light sensitivity, or abnormality in the photoreceptors of the retina, as is the case with people who have congenital, inherited achromatopsia.

Currently there is no cure for achromatopsia. But there are studies and some treatments to help live with achromatopsia.

The National Eye Institute currently has a study going on involving a CNTF implant. According to the research, CNTF is a natural chemical found in the body that promotes the survival and functional a nerve cells. This implant’s hope is to learn whether CNTF can improve visual acuity or color vision, and whether it can reduce sensitivity to light.

There are also dark or special filter glasses or red-tinted contact lenses to reduce photophobia and potentially improve visual acuity; low vision aids; and occupational aids.

http://www.achromat.org/ - I used this reference as a starting point for researching my topic/subject. This website is a network of information for individuals and families who are affected by achromatopsia. There is a pdf of a book called “UNDERSTANDING AND COPING WITH ACHROMATOPSIA” by Frances Futterman that I used as a reference when writing about my topic.

http://www.ncbi.nlm.nih.gov/pubmed/20301591 - I choose this website as a reference to the heredity question and also for the massive amount of information it contained on the subject of achromatopsia. This website is run by The National Center for Biotechnology Information and provides access to the biomedical and genomic parts of many subjects. The information taken from this website can be linked to the second paragraph.

https://clinicaltrials.gov/ct2/show/NCT01648452 - This website provided me with the information on one of the most current studies by the National Eye Institute (NEI) for treatment of achromatopsia. (The study is ongoing but not recruiting participants.) The data taken from this reference can be directed linked to the end of my blog.

Terms: Achromatopsia, congenial, central nervous system, vision, light sensitivity, studies, National Eye Institute (NEI), data, National Center for Biotechnology Information, biomedical, genomic, subjects, treatment, color, understanding and coping, visual disorder, color sensitivity, cerebral achromatopsia, colorblind, rods, cones, blind, eye, specialists, diagnosed, monochromatic, contrast, visual perception, rods, photoreceptors, neurologists, retina, glasses, contacts, asymptomatic, and chemicals.

My topic is achromatopsia. This is related to the chapter because it is a rare subtype of color blindness. I am interested in this because I really love colors. The thought of not seeing any colors, like in this type of colorblindness, is very sad to me. Therefore, I wanted to find out the exact mechanics behind it. I also wanted to learn about the effects of the condition on the actual people who are afflicted.

Achromatopsia is a rare disorder that occurs in 1 of every 33,000 people in the United States. It is a type of colorblindness characterized by the presence of malfunctioned cones in the retina. Cones are a type a photoreceptor used to detect colors in daytime. In achromatopsia, the cones do not work correctly, which only allows vision in black, white, and gray. There is another type of achromatopsia called incomplete achromatopsia or blue cone monochromatism. This is when only the S-cones function properly. This leaves only cones that pick up shades of blue and rods, the nighttime photoreceptor to see with. This type is even rarer than complete achromatopsia, and predominately occurs in men at anywhere between 1 in 50,000 and 1 in 100,000. The odds of a female getting this disorder are nearly 1 in 10 billion.
Not being able to see color is much more debilitating than one might think. Due to the fact that those with achromatopsia cannot use their cones, they must rely on their rods in order to see. This is a considerable problem because rods are meant for vision in low light. This leads to hemeralopa, or day blindness. Day blindness refers to when what one sees appears to extremely bright. Those with day blindness are driven to squint in all non low-light situations. This is closely linked with photophobia, which is light sensitivity. Another side effect of achromatopsia is pendular nystagmus. This is a term for uncontrollable quivering of the eye. This disorder also causes greatly reduced visual acuity. This in turn can lead to problems and difficulty in school and at work.
The side effects of achromatiopsia can be especially difficult for children. If a child squints constantly from the hemeralopa and has jerky eye movements from nystagmus, they could face ridicule in school. Luckily there are ways to alleviate the negative effects. For example, there are special red or amber colored glasses and contacts that can be used to correct the hemeralopa and possibly even aid in visual acuity. As for nystagmus, this usually only occurs in young children and eventualy tapers off as a person grows older. This goes to show that even though achromatopsia is a troubling disorder, there are still many ways to improve quality of life.

Terms: achromatopsia; colorblindness; cones; retina; photoreceptors; S-cone; Blue cone monochromatism; rods; hemeralopa; day blindness; nystagmus

Sources:
http://www.aapos.org/terms/conditions/10
I liked this site because it provided clear and concise basics of the disorder. It acted as a basis for me to understand everything. I trust it because it is an official association's webpage.

http://www.achromatopsia.info
I liked this site because it was a webpage for people with achromatopsia. This gave it a more personal view with a lot of good information and videos to help explain concepts. The videos helped me to see this in the lives of actual people.

http://www.ncbi.nlm.nih.gov/books/NBK1418/
This site was helpful because it was so technical and in depth. It allowed me to find medically accurate terms and definitions for the topic areas.

The study of color vision is especially interesting given the nocturnal habits of animals. In chapter 5, we learn that cone photoreceptors are divided into type, depending on what wavelength they are specialized for (S, M, or L). As humans and many types of primates rely more on vision than other senses, it is particularly interesting to study the effects of evolution and nocturnal activity on their photoreceptors and visual interpretation. The Bayesian approach uses a working knowledge of the world to unconsciously assign probability to various scenarios which might serve as explanations for a given scene. We then use a committee-based decision making strategy to figure out what we are looking at (all of which occurs without a conscious thought). The idea that vision relies on implicit understanding and photoreceptor stimulation indicates that it is an evolutionary trait, rather than a learned activity. With this in mind, we can explore the role of evolution in color vision.
In nocturnal animals, color vision plays an important role in survival. The folivorous wooly lemur is a nocturnal member of the primate family, making it a good study for this research question. This specific type of lemur seems to have developed photoreceptors especially responsive to certain green leaves that they prefer eating. Without this adaptation, it is unclear if they could identify primary food sources. Additionally, it is not likely other species would benefit from the same adaptation, unless they favor the same green leaves.
Quite a bit of research has explored the color vision of marsupials, a special case which evolved separately from humans or primates. In particular, the tammar wallaby is known to have dichromatic vision, and is in fact the only species to show no evidence of a third cone photoreceptor. Dichromatic vision is a condition where only two types of cone photoreceptors are present, instead of the three that we have. As a group, marsupials are largely thought to be dichromats, although ongoing research may be able to confirm using behavioral research methods.
With more research, we’ll know more details about the various differences in color vision among species. In some cases, studies have shown how certain species or groups have adapted their color vision for a better chance of survival. For now, we can be sure evolution will continue to take its course in prompting these helpful adaptations. Taken as a whole, photoreceptors are highly specialized for detecting certain types of light, including certain ranges of wavelength that make up the color spectrum. Evolution has already given many examples of how photoreceptors can be highly specialized to benefit the organism.

Terms: Color vision, cone photoreceptors, wavelength, Bayesian approach, dichromat,

http://www.ncbi.nlm.nih.gov/pubmed/18627773
Color vision in humans and animals is extremely varied depending on the needs of the animal for cone and rod photoreceptors.

http://eds.b.ebscohost.com.proxy.lib.uni.edu/eds/pdfviewer/pdfviewer?vid=2&sid=9680c1d5-5eab-4464-8658-73554793a3ba@sessionmgr111&hid=104
This article gave some good insights on testing color vision, particularly of marsupials. The tammar wallaby is a special case study highlighting the behavioral approach to studying color vision.

http://eds.b.ebscohost.com.proxy.lib.uni.edu/eds/pdfviewer/pdfviewer?vid=2&sid=63a696f8-1c7f-4c65-906f-23b938451cc2@sessionmgr113&hid=104
This article explores the color vision of the folivorous wooly lemur and how their photoreceptors have adapted for nocturnal activities.

The topic I chose this week was the trichromatic theory of color vision. I chose this because I really didn’t completely understand it in the text. I also love colors and it fascinated me that all the various hues three cones or receptor types and that makes up the thousands of colors we see every day. There is so much in this class that we just simply daily see that in reality is the working of very intricate actions in the brain and eye.

This theory says that there are three cones that perceive the colors. These are the S, M and L cones. Short, medium and long, each responds to a color. So since a blue has a short wave length the S cone is activated, the color green has medium wave length so the M cone is sensitive to it and red is long wave and the L cone is sensitive to it. As the colors come at us the impulses trigger the cones each color reacts within the specific cones and we see the color. What I found really interesting was that the video showed shining the color yellow through a prism it is still seen as yellow but a mixture of red and green is perceived as a combination with yellow at the center.

There is more to seeing the color than simply the three cones. The cones are connected to other nerve cells. A ganglion cell gathers the information from the nerves and gives the response of the color for a particular area of the retina. The ganglion has a center and a surrounding area and each are fed by different types of cones. It kind of reminded me of the binary 0,1. In this case it is + if the center is excited by the stimulus and – in the surrounding area. The surround area is called an off because it inhibits not stimulates. This can be flipped and the center can be off and surround be on. What seemed to be was that this is only part of the perception of color. There is more to our sensing of color than the three cones.

One thing I really get is how more can be added but it doesn’t necessarily have to debunk earlier findings. There was quite a bit I really struggled with understanding, so hopefully I can ask rather than answer questions on Thursday. It is also why this post is rather short in comparison with my other posts. I struggled with finding very much on the internet about the subject that wasn’t either a paragraph long or else written way over my head. My best information came from the videos I watched.

Terms: trichromatic theory, color vision, cones, receptors, retina, ganglion, nerve, stimulus

https://www.youtube.com/watch?v=V73k_0KuUJo The video gave a lot of good information and watching it was easier than reading it.

http://en.wikipedia.org/wiki/Young%E2%80%93Helmholtz_theory

http://webvision.med.utah.edu/book/part-viii-gabac-receptors/color-perception/
The two web pages has some good history on the theory, as well as some good information, but not as easy to get through as the video

I decided to research the topic of colorblindness. This relates to the chapter, because it was mentioned in the chapter and it concerns our ability to process the information that we are receiving from the outside world. I chose this topic, because I know several people who have difficulty with many daily tasks because of their color blindness.

Color blindness is the inability or decreased ability to see color or to perceive color differences under normal lighting conditions. The most common cause of this is a developmental problem with or ore more sets of cones in the retina that perceive color and then transmit the information to the optic nerve. This cause is genetic and affects mostly males. Color blindness can also be caused by Parkinson's disease, cataracts, Tiagabine (a drug used to treat epilepsy), Leber's hereditary optic neuropathy, Kallman's syndrome, diabetes, aging, or physical damage to the eye.
There are three main types of color blindness: monochromacy, dichromacy, and anomalous trichromacy. There are also several subtypes within these main types. The most severe type is Monochramacy. This is the condition of possessing only a single channel for conveying information about color. The technical term for this is achromatopsia, or total color blindness, which is the complete inability to see color. The most common type of color blindness is red-green color blindness. This when one is unable to or has difficulty distinguishing red and green hues because of the absence or mutation of the red or green retinal photoreceptors. This type is part of the dichromacy color blindness. This when someone can match any color they see with some mixture of just two primary colors. This is different from people with fully functioning color perception that require all three primary colors. Because of this, certain pairs of colors, like red and green, that seem quite different to the normal viewer might appear to be the same color to someone with this type of color blindness. Dichromats often have difficulty with daily tasks like picking out clothes to wear or distinguishing between the colors of a stoplight. The final type is anomalous trichromacy. People with this type require different color matches from people with normal vision. For example, in order to match a given spectral yellow light, they may need more red light or green light in a red/green mixture than a normal viewer.
Color blindness has been cured in monkeys using gene therapy, but this will not be available to humans until it can be proven to be safe. The only other treatment available for color blindness is filtered lenses that enhance color perception. These lenses can be difficult to find, though, as they are only available from a limited number of eye care practitioners. It is mostly up to the affected person to adjust their lives accordingly with the condition. One may need to memorize the order of stop lights rather than the colors or organize their clothes in a way that will prevent them from accidentally put on clashing colors.

Terms: Color blindness, Cones, Achromatopsia, Photoreceptors, Monochromacy, Dichromacy, Anomalous Trichromacy, Perception

https://www.youtube.com/watch?v=8Aaivktz8G0 I used this source, because it had all of the basic background information on the topic and presented it in an easy to process manner.

http://en.wikipedia.org/wiki/Color_blindness I used this source, because it had a lot of technical information that went further into depth than many of the other sources I found.

http://www.allaboutvision.com/conditions/colordeficiency.htm I used this source, because it focused more on how people with color blindness are affected by the condition, rather than just the technical information about the condition itself.

For this weeks research assignment, I chose to do more research on Achromatopsia. Achromatopsia is defined as a non-progressive and hereditary visual disorder which is characterized by decreased vision, light sensitivity, and the absence of color vision. Achromatopsia is sometimes called ‘Day Blindness’, as these subjects see better in subdued light. Persons with complete Achromatopsia will have reduced vision (20/200 or less) due to an abnormality of the retina. They also have no color vision, sensitivity to light (photophobia) and the presence of nystagmus (shaking of the eyes). This condition affects approximately one in 40,000 births. Its prevalence varies in different parts of the world. Because there is a genetic link, it is more common in regions where there is a high rate of consanguineous marriages (marriages between relatives) and in the eastern Pacific islands of Pingelap.

This hereditary visual disorder coincides with this chapter because this chapter starts to discuss our visual system in accordance to color. This chapter discusses which parts of the eye are susceptible to "seeing" colors and how we process that information.

I was interested in this topic because it is one of those abnormalities that I tend to focus on. The way I look at it, if we can understand 'what is wrong' maybe that will give us a better understanding of our visual system as a whole. Achromatopsia is caused by an abnormality of the retina, that portion of the eye responsible for “making the picture”. In the retina, there are three types of cells called cones that are responsible for normal color vision. These are the red, green, and blue cones. A balanced distribution of these cells is necessary for normal color vision. Sometimes people have a reduced complement of the cones, in which case they will have partial or incomplete achromatopsia. Since achromatopsia is an inherited condition and so far four genes are known to be associated with this condition. The four chromosomes that may have changes associated with achromatopsia are chromosome 14, chromosome 8q21- q22, chromosome 2q11 and chromosome 10q24. As I was reading through some of the research for this assignment, I came across studies that were being done across the nation. These studies were examining treatment plans and executions for dogs and mice. Research continues on developing genetic treatments for achromatopsia. In animal models of achromatopsia (dogs and mice), genetic therapy has shown positive results in restoring some cone function. Because the incidence of achromatopsia is rare compared to other retinal disorders, the amount of research and funding may be limited. However, the knowledge being gained from the more extensive genetic treatment research being done to treat conditions such as retinitis pigmentosa and macular degeneration, will likely advance the ability to genetically treat achromatopsia.

Currently there is no treatment for Achromatopsia, although deep red tinted glasses or contact lenses can reduce symptoms of light sensitivity. The potential treatment being tested uses an engineered adeno-associated virus (AAV), a safe, man-made virus that delivers healthy copies of the ACHM gene to the cells of the retina, replacing the defective copies of the gene. A single treatment is expected to stop the disease for at least several years, perhaps a lifetime. The AAV delivery system is successfully being used in clinical trials of Leber Congenital Amaurosis gene therapy that have restored vision in more than 50 adults and children who were virtually blind. Previous research has shown promising signs of efficacy in dog and mouse models of ACHM.

References:
http://www.aapos.org/terms/conditions/10 I chose this website because it gave a general background of this hereditary disease. It gave some visual aid as to what someone with this disease would look like and also how typically these abnormalities are found.

http://www.achromatopsia.info/achromatopsia-genetic-treatmen/ I chose to use this website because of the background information leading up to the clinical trials on dogs from mice. It also had a neat video showing the effects of the therapy vs. no therapy.

http://www.agtc.com/news/detail/the-university-of-florida-and-agtc-secure-8.4m-grant I chose this website because it gave "hope" that there is more money being funded to created some type of solution to this disease.

TERMS: Achromatopsia, color vision, 'Day-Blindness', retinitis pigmentosa, macular degeneration, light sensitivity, ACHM gene, cones, gene therapy retina, nystagmus, photophobia, hereditary visual disorder

My topic for this blog is colorblindness:

Colorblindness relates to this chapter because "seeing" has so much to do with sensation and perception; and the colors we see have everything to do with the sensation we get from what we see.

Color blindness is a vision defect wherein the eye perceives some colors differently than others. This condition may be hereditary or may be caused by a disease of the optic nerve or retina.

Color blindness can be classified as inherited, partial or complete. Inherited color blindness is most common in males, affecting both eyes but does not worsen over time, this basically means that once you have it, you have it forever and there is no cure. Partial color blindness affects some colors while complete color blindness, which is a rare condition, affects all your color vision. Most people affected by color blindness see red instead of green or blue instead of yellow. Color blindness is usually classified as a disability; however, in some situations color blind people may have advantages over people with normal color vision. There is some evidence that color blind individuals are better at penetrating color camouflage and at least one scientific study confirms this under controlled conditions. Seeing how someone with one of the diagnosis we learn about throughout these chapters having an "advantage" is always interesting and nice to hear. Most of the males in my family are color blind however, it doesn't seem to affect any of them in their every day lives.

One weird thing that I have always wondered about colors is "how do we know that the colors we see are the same as what other see?" if we are told that "red" is red our entire life we would refer to it as red but maybe someone else sees your red as their blue and they just call it red because that is what they have always seen as red. (I'm not sure if that made sense at all) but colors have always been interesting to me. It is intriguing to know that we can never know what other people see and if they perceive things the same way that we do.

I think the worst type of color blindess would be; Congenital colorblindness is the primary type since it is a sex-linked trait, inherited on the X chromosome. People who have congenital colorblindness have never experienced color and do not understand the concept of gray. Congenital colorblindness is much more common in males since males have one X and one Y chromosome and females have two X chromosomes. Females are typically carriers for the disease because only one of their chromosomes are infected. It is very rare that both X chromosomes in a sex-linked disease are mutated since both parents would have to have be infected and give the disease on both of the daugther's X chromosomes which is not as likely as a son getting the one X chromosome.

Colorblindness can be very server or more mild but either way it is something that once diagnosed the person with it must deal with it for the rest of their lives.

Websites I used:
http://psychology.wikia.com/wiki/Color_blindness: I like this website because it talks abou6t how some people with colorblindness are actually at an advantage compared to those who are not.

http://www.color-blindness.com/; this website had quizzes to discover if you were colorblind yourself and also gave examples of how people deal with colorblindness and things they can do to cope with or deal with it.

http://users.start.ca/users/joneil/colour2.htm; this website was for people who are NOT color blind to try to get them to understand what people who are color blind experience. This is cool to me and interesting because of course we would all love to know how other people see/interpret/perceive things.

Terms: Terms: Visual system, colorblindness, visual system, dischromatism, anomalous trichomatism, protanopia, rods, cones, disorders, pigment, wavelength, color deficiency, perceive, sensation.

color blindness.
im doing color blindness not because so many others have done it but because my dad is partially colored blind and also because I have always wondered what it would be like to never know colors.
color blindness is such a crazy thing that ones eyes have devloped without the tools to detect color. people can go color blind when the rods and cones in the eye in someway get damaged. color blindess can effect your daily life if your driving down the street and you dont happen to get to a stop light that has red green and yellow in a differnt order then what your used to you could go right through it and get in an accident. because color blindess is a diffency in a way ones sees color. one might not be able to see red and green and all they see is yellow and the website says. the last website i have listed is a webiste where you can go to test your colorblindness. this is pretty cool to find out where you stand with color blindness. many people dont even know they are color blind untill somone says somthign to them because they were born that way and think its 100% normal.

http://www.allaboutvision.com/conditions/colordeficiency.htm
http://www.colormatters.com/color-and-vision/what-is-color-blindness
http://colorvisiontesting.com/

I decided to research the topic of colorblindness. This relates to the chapter, because it was mentioned in the chapter and it concerns our ability to process the information that we are receiving from the outside world. I chose this topic, because I know several people who have difficulty with many daily tasks because of their color blindness.

Color blindness is the inability or decreased ability to see color or to perceive color differences under normal lighting conditions. The most common cause of this is a developmental problem with sets of cones in the retina that perceive color and then transmit the information to the optic nerve. This cause is genetic and affects mostly males. Inherited color blindness can be congenital (from birth), or it can commence in childhood or adulthood. Depending on the mutation, it can be stationary, that is, remain the same throughout a person's lifetime, or progressive. As progressive phenotypes involve deterioration of the retina and other parts of the eye, certain forms of color blindness can progress to legal blindness, i.e., an acuity of 6/60 or worse, and often leave a person with complete blindness. Color blindness can also be caused by Parkinson's disease, cataracts, Tiagabine (a drug used to treat epilepsy), Leber's hereditary optic neuropathy, Kallman's syndrome, diabetes, aging, or physical damage to the eye. It can also be caused by damage to the brain such as through shaken baby syndrome and accidents and other trauma which produce swelling of the brain in the occipital lobe. Exposure to ultraviolet light can also damage the retina severely enough to cause color blindness. Often times, these damages present themselves later on in life. This means that one may not go color blind right when the damage happens, but rather years later on. There is not much data on the subject, but it is hypothesized that a deficiency in vitamin A may also be a contributor in color blindness.

There are three main types of color blindness: monochromacy, dichromacy, and anomalous trichromacy. There are also several subtypes within these main types. The most severe type is Monochramacy. This is the condition of possessing only a single channel for conveying information about color. The technical term for this is achromatopsia, or total color blindness, which is the complete inability to see color. Although the term may refer to acquired disorde such as cerebral achromatopsia, also known as color agnosia, it typically refers to congenital color vision disorders (more frequently rod monochromacy and less frequently cone monochromacy). In cerebral achromatopsia, a person cannot perceive colors even though the eyes are capable of distinguishing them. Some sources do not consider these to be true color blindness, because the failure is of perception, not of vision. They are forms of visual agnosia. The most common type of color blindness is red-green color blindness. This when one is unable to or has difficulty distinguishing red and green hues because of the absence or mutation of the red or green retinal photoreceptors. This type is part of the dichromacy color blindness. This when someone can match any color they see with some mixture of just two primary colors. This is different from people with fully functioning color perception that require all three primary colors. Because of this, certain pairs of colors, like red and green, that seem quite different to the normal viewer might appear to be the same color to someone with this type of color blindness. Dichromats often have difficulty with daily tasks like picking out clothes to wear or distinguishing between the colors of a stoplight. The final type is anomalous trichromacy. People with this type require different color matches from people with normal vision. For example, in order to match a given spectral yellow light, they may need more red light or green light in a red/green mixture than a normal viewer.
Color blindness has been cured in monkeys using gene therapy, but this will not be available to humans until it can be proven to be safe. The only other treatment available for color blindness is filtered lenses that enhance color perception. These lenses can be difficult to find, though, as they are only available from a limited number of eye care practitioners. It is mostly up to the affected person to adjust their lives accordingly with the condition. One may need to memorize the order of stop lights rather than the colors or organize their clothes in a way that will prevent them from accidentally put on clashing colors.

Terms: Color blindness, Cones, Achromatopsia, Photoreceptors, Monochromacy, Dichromacy, Anomalous Trichromacy, Perception

https://www.youtube.com/watch?v=8Aaivktz8G0 I used this source, because it had all of the basic background information on the topic and presented it in an easy to process manner.
http://en.wikipedia.org/wiki/Color_blindness I used this source, because it had a lot of technical information that went further into depth than many of the other sources I found.
http://www.allaboutvision.com/conditions/colordeficiency.htm I used this source, because it focused more on how people with color blindness are affected by the condition, rather than just the technical information about the condition itself.

(1a) Gender Differences in Color Blindness and the Visual System

(1b) Color blindness was discussed in the chapter but didn’t go into depth on gender differences.

(1c) I was interested in this topic because males and females are quite active now a days providing opinions on why their counterpart, whether male or female are better equipped in society both physically or mentally.

(2) Color blindness, or color vision deficiency, is the inability or decreased ability to see color, or perceive color differences, under normal lighting conditions. The most identifiable cause is that the cones that perceive color in light and transmit information to the optic nerve are undeveloped or damaged. This fault in cone development is sex linked, photopigments are carried on the x chromosome which males have one x chromosome and females have two. Which give males a higher probability to have photopigment problems compared to females. Certain causes linked to color blindness include: acquired through drugs or disease, it could be inherited, genetics, brain damage, retinal damage, and much more. Currently there are no treatment options to cure color deficiencies.

Gender differences in male and female are always a popular but yet sensitive topic in today's society. James Owen, a writer for National Geographic, dove into one of these topics called “Men and Women Really Do See Things Differently.” What he found is that men and women really don’t see eye to eye, literally. Studies have shown that females are much better at discriminating among colors, while males are excellent at tracking fast-moving objects and discerning detail from a distance. These evolutionary differences may be rooted to the hunting and gathering past. Researchers delivered the notion that throughout the visible spectrum, males require longer wavelengths than females in order to experience the same hue. Longer wavelengths are associated with warm colors, like red and orange. The neuron development in the visual cortex is said to also contribute to seeing shades of blue, greens and yellows. Mens visual cortex is boosted by hormones also, 25 percent more to be exact, which gives them greater ability to see quick changing details from a far, better than colors. The studies findings go on to support the hunter-gatherer hypothesis, which states that sexes evolved distinct psychological abilities to fit their prehistoric roles. Males being the hunters, and females being the gatherers.

My last source provides some good information in regards to the perception of color and the visual system. Men and women look at different things because they interpret the world differently. No matter what, women and men have their own ways of seeing the beauty of things, sometimes the same might I add. Men examine pictures and the environment using a rapid eye movement, women more so tend to gaze. It is natural for men to look for a threat since it is evolutionary part of their make up. Women on the other hand tend to gaze and acknowledge the more social aspect of a picture or the environment. We both see beauty, we just tend to look at it differently.

(3) Terms : color blindness, color discrimination, color deficiencies, color in visual cortex

(4) http://en.wikipedia.org/wiki/Color_blindness
This source provided credible information that I used to define color blindness, show the causes of color blindness, and the treatments of color blindness. This source provided more thorough information on color blindness than the textbook.

http://news.nationalgeographic.com/news/2012/09/120907-men-women-see-differently-science-health-vision-sex/
This source provided credible information that I used to discuss gender differences in color perception rooted back to the evolutionary idea of hunters and gatherers.

http://www.sciencedaily.com/releases/2012/11/121130222243.htm
This last source was the best I could find, other sources tended to repeat information from my previous sources. So I used the information from this article to explore how men and women view the visual world differently.