Please
read chapter 5.
After reading chapter 5, please respond to the following questions:
What were three things from the chapter that you found interesting? Why were they interesting to you? Which one thing did you find the least interesting? Why? What did you read in the chapter that you think will be most useful to in understanding Sensation & Perception? Finally indicate two topics or concepts that you might like more information about.
Note:
Keep in mind that there are no scheduled exams. When you make you posts
make sure they are of sufficient caliber that the could be used as
notes in a test - since the posts are what we are doing in lieu of an
exam. Be sure to use the terms and
terminology in your posts.
While reading chapter 5, I found many things interesting, but found a few things particularly interesting. I enjoyed learning that color is not a physical property of things in the world, but it is related to a physical property. It is actually a creation of our minds. Objects in our world appear to be certain colors because of our particular visual systems. As we have learned, the human visual system sees a small range of the electromagnetic spectrum between the wavelengths of 400 and 700 nm. The “color” we see is correlated with the wavelengths of the light rays reaching the eye from the object the light is being reflected from. Most of the light we see is actually reflected light. Light sources can range from the sun to light bulbs, and they emit a broad spectrum of wavelengths that hit surfaces in the world around us. Some wavelengths are absorbed, making the object appear darker; while some are reflected and some of those reach the eyes. I really enjoyed the quote by Steven Shevell because it really helped me to understand how color isn’t a property, but an interaction that our brain perceives. Shevell said, “There is no red in a 700 nm light, just as there is no pain in the hooves of a kicking horse.” Color is the result of the interaction of a physical stimulus with a specific nervous system. I think this is an important concept to review because it is important to understand how we see our world, and that this is another example of how our brain ‘lies.’
I also enjoyed reading about trichromacy because I enjoyed reading about rods and cones in chapter 2. The two kinds of photoreceptors in the retina are rods and cones. Rods are sensitive to scotopic light levels; these are dim light levels at or below the level of bright moonlight. There are three types of cones named for their position on the spectrum of the height of their sensitivity. S-cones are sensitive to short wavelengths, M-cones are sensitive to middle wavelengths, and L-cones are sensitive to long wavelengths. I liked that this is easy to remember because each type has the letter that corresponds to the length of the wavelength each is sensitive to. After reading about the univariance problem, I learned that you can make any wavelength look like any other just by adjusting the intensity of the light. This doesn’t work in the three-cone world of our color vision as humans. With humans a specific light produces a specific set of responses from the three cone types. The idea that the color of any light is defined in our visual system by the relationships among three numbers is known as trichromacy, or the trichromatic theory of color vision.
My favorite concept from the chapter was color space, because I love art and really enjoy learning about colors. The range of our experience of color can be described by reference to a three-dimensional color space. The useful terms used for defining color space in regard to color space are hue, saturation, and brightness. A hue is the chromatic aspect of a light, each point on the spectrum defines a different hue. The saturation dimension corresponds to the amount of hue present in a light. For example, white light has zero saturation. Brightness is the perceptual consequence of the physical intensity of a light. The sun’s light is physically more intense than the moon’s intensity. I thought it was interesting that there are nonspectral hues that can only result from light mixtures that are not present in the spectrum. I really enjoyed reading about color space, because I love how beautiful colors make our world but haven’t taken the time to really investigate the concept.
I found the concept of lateral geniculate nucleus to be the least interesting thing from the chapter because I did not enjoy learning about it in chapter 3 and reviewing did not make it more interesting to me. The lateral geniculate nucleus is a relay on the pathway from the retina to the visual cortex. It is a structure in the thalamus of the brain that receives input from the retinal ganglion cells and has input and output connections to the visual cortex. I know that this is an important part of the visual system, as is every part, but I just don’t find it very interesting to read about.
I think that the concepts of trichromacy and the problem of univariance will be very important to further understanding sensation and perception. The problem of univariance is the fact that an infinite set of different wavelenfth-intensity combinations can elicit exactly the same response from a single type of photoreceptor. One photoreceptor type cannot make color discriminations based on wavelength. Trichromacy is the theory that the color of any light is defined in our visual system by the relationships between a set of three numbers, the outputs of three receptor types now known to be the three cones. I did not understand the complexities of how our eyes/brains perceive wavelengths and light spectrums before reading this chapter. I think this is important because we should appreciate how our eyes allow us to see, or not see and perceive the color in our world. After reading about these concepts I better appreciate how I perceive the beauty in the world around me.
I would like more information about the concept of metamers, because I understand that they are mixtures of different wavelengths that look identical but I would like further explanation on the subject to better understand it. I would also like more information about achromatopsia because I think it is interesting how a person could lose their color vision after damage to their brain/central nervous system. I 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 damage to that area of their brain.
Terms: wavelengths, trichromacy, retina, rods, cones, scotopic, S-cones, M-cones, L-cones, univariance problem, trichromatic theory of color vision, spectrum, color space, hue, saturation, brightness, chromatic, nonspectral hues, lateral geniculate nucleus, visual cortex, thalamus, retinal ganglion cells, metamers, achromatopsia
No love for the LGN??? Nobody ever loves the LGN. haha. Anyway, glad you liked the color vision stuff. Definately interesting material. There are people I go to school with that just study color vision. I took a seminar from Mike Webster on color vision and there is definitely a lot to know about the various phisiological, psychological, and even phenomenological aspects of it. solid post.
I really enjoyed reading about the Problem of Univariance. I am not sure if I completely understand this topic, but I specifically found it really interesting that we fail to see colors when in a dimmer light. Dim light only stimulates our rods, which is our shape photo receptors. So, basically the light is always there, but we don't see them! Our S-cones, M-cones, and L-cones are all based around photopic or scotopic light. This was interesting to me because it almost sounds like we make our own night and day with our rods and cones. Maybe I am not understanding it correctly, but this idea popped into my head when reading, and it sounded pretty rad!
Secondly, I found learning about afterimages, adapting stimulus, and negative afterimage very interesting. I found them interesting because this often happens in everyday life that is kind of out of the ordinary and I never really knew why. Afterimages seem to be like taking a picture. If the flash is used, you can see a flash when you blink your eyes.
Lastly, I found it very interesting to learn that people see colors the same way. I have always wondered about this. If we see different colors different, if some are brighter or dimmer for people. obviously, I knew that cases like deuteranope were around and protanope, but even then, this is all new information and very interesting to finally learn!
I did not find the history of Trichromatic Theory very interesting because I just really am not interested in it. With perception, things are so hard to understand, I just like to be told why certain things are a certain way and that be that!
One thing I found that will help me understand sensation and perception the most in this chapter would have to be the information in the beginning of the chapter about wavelengths. The graphs really gave me a good understanding of how we see them, and how we don't see them!
I would like to learn more about achromatopsia. It seems very out of the ordinary and I would like to research people who might have this condition and see what they are like.
Another topic I would like to research further would be Agnosia. Basically for the same reasons I would like to learn more about achromatopsia. Ideally, I would like to find some case studies for these conditions.
Terms:achromatopsia, agnosia, rods, s-cones, m-cones, l-cones, Trichromatic theory, photopic, scotopic, problem of univariance.
It's it a trip to think there is all that energy out there that we can't even detect? It makes you question the veridicality of your own perception. There's a lot we can't sense out in the world, which in my opinion means there's a great deal we could potentially be wrong about. I think the color stuff is interesting as well.
I found the part of the chapter about rods and cones to be interesting. In the retina there are two different kinds of photoreceptors, rods and cones. The rods detect low light levels. These are also known as scotopic light levels, below or at the brightness of moonlight. There are three different cone photoreceptors in the retina that have different photopigment wavelength sensitivity. The short-wavelength cones (S-cones) have a peak at about 440 nm are known as the “blue cones.” The middle-wavelength cones (M-cones) peak at about 535 nm and are known as the “green cones.” The long-wavelength cones (l-cones) peak at about 565 nm and are known as the “red cones.” You cannot just call them red, green or blue cones because if you only had one set of cones you would see the world in a shade of grey. These cones are the reason we can tell the difference between different wavelengths and interpret color. I found this interesting because it was something that I didn’t know before.
I also thought the section of the chapters labeled lights and finger-paints was interesting. I did not know that to make yellow on a computer screen they actually use a combination of red and green dots. This is called an additive color mixture because the perception of the color is added together. This can be done in other ways besides on the computer screen. The pictures done with little dots of color are another example of this. George Seurat’s painting La Parade is an example of additive color mixture. A subtractive color mixture is combining two pigments that subtract light from each other leaving the remainder to contribute to the color we perceive. This is like mixing red and green finger paints together making the color we perceive as brown.
I also really liked reading about the Young-Helmholtz theory. This is a color matching technique where an observer would try to use different amounts of primary colored lights and match another color. This experiment showed that you only needed these three colored lights to match any light color. I thought it was interesting that Young and Helmholtz discovered that these three colors were responsible for the human experience of color before physiology could prove it.
I thought the concept of lateral geniculate nucleus was the least interesting part of the chapter. The lateral geniculate nucleus is a structure in the thalamus of the brain that receives input from the retinal ganglion cells and has input and output connections to the visual cortex. I thought this was a little bit confusing.
I think the most important thing in the chapter pertaining understanding sensation and perception is the concept of the different rods and cones we have in our retina that help us perceive color.
I would like to learn more about metemers and color constancy.
Terms: retina, rods, cones, photoreceptors, scotopic, photopigment, short wavelength cones, middle-wavelength cones, long-wavelength cones, additive color mixture, George Seurat, subtractive color mixture, Young-Hemholtz theory, primary colors, lateral geniculate nucleus, thalamus, retinal ganglion cells, visual cortex, metemers, color constancy.
Yeah, the paints versus lights color mixing is a trip. The thing about computer monitors is they used to all be CRT which meant they had 3 "guns", red, green, blue, which varied in intensity and of which pixels they lit up and which combinations of the firings would lead to a certain "color" on the screen. Even today, you have RGB values and codes that correspond to different color properties. For example, make something 0 0 0 and its black on the screen. Make something 255 255 255, then this is a white color on the screen. 128 128 128 standard neutral gray color. Values of each of these references get you different hues.
The first topic I found to be interesting in chapter 5 was trichromacy. Trichromacy has to do with rods and cones again like we had read about earlier in the book. We use rods for our night time vision and we use cones for our daylight and color vision. Trichromacy really deals with the three types of cones, S-cones, M-cones, and L-cones. S-cones are our short wavelength receptors, M-cones are our middle length wavelengths, and L-cones are our long wavelengths. A specific set of light will induce a response for a specific wavelength. If we are to mix wavelengths then we can create metamers, which are different mixtures of wave-lengths that look identical. More generally, any pair of stimuli that are perceived as identical in spite of physical differences. We can create different colors through adding and subtracting wavelength. Additive color mixture is a mixture of lights (many different wavelengths) and combining them. So many wavelengths of red and green will create a color of yellow when added together. Obviously yellow isn’t made from red and green. Subtractive color mixture tells us that a mixture of pigments in will be subtracted by each other and that is what we perceive.
Another topic of interest was afterimages. An afterimage is a visual seen after the stimulus has been removed. I can relate to this, and so can most people, when we look at a light and then look away we have an image in stuck in our head. When we look at a color and then look away, the opposite color to the original will appear. The first color we look at is the adapting stimulus and the color we see after we remove the original color is the negative afterimage. An example would be looking at something yellow and then removing to see blue in your afterimage.
Lastly, I thought the section on “Does everyone see colors the same way?” to be very interesting. In general, most people have the same type of standards for color variation with some differences arising from age. Some people have color blindness though, which is usually when the gene code for M and L cones is messed up. Both L and M cones are on the X chromosome so it’s rare for women to have it because they have two X chromosomes. 8 percent of men have some sort of color deficiency. A person who suffers from an absence of M-cones is deuteranope and a person who suffers from an absence of L-cones is protanope. In rare cases someone will suffer from an absence of S-cones which is called tritanope. There are also two forms of color blindness. Cone Monochromat people have only type of cone and see the world in gray scale with no color. Rod monochromat people have no cones and see no color either. They are also visually impaired in bright light because of the absence of cones.
My least favorite thing in this chapter was the parts about illuminant. I didn’t really understand how some reflective light can hit our eyes while other reflective light can’t. Also, I didn’t really understand why some colors change when they hit different types of illuminants.
I think the most useful information in this chapter was the parts about trichromacy. I think it was important to understand how our cones create and decipher color. It was also interesting to see how we mix wavelengths of cones to create new colors.
Topics I would like to learn more about would be color constancy, Illuminants, and metamers.
Terms: illuminants, metamers, color constancy, trichomacy, L-cone, M-cone, S-cone, protanope, tritanope, deuteranope, monochrmat, color blindness, afterimage, adapting stimulus, negative afterimage, additive color mixture, subtractive color mixture.
I think we do not really see color the same way. Even in non-color deficient humans, there is genetic variation in the opsins that code for the photopigments for each cone type, leading to different spectral sensitivities for each person based on this. Thus the 540 nm light that looks "green" to you, might look like a different hue of green or "greenish-yellow".
Over all, I found this whole chapter interesting, as an artist and seeing color in my art it makes this chapter interesting for me. Trichromatic theory of color vision, the theory that the color of any light is defined in our visual system by the relationships of three numbers, the outputs of three receptor types now known to be three cones. Odd how our cones can interpret colors that in our word actually don't make that color (red + green = yellow). Like this theory there is also the opponent color theory. The theory that perception of color is based on the output of three mechanisms, each of them based on an opponency between two colors (red-green, blue-yellow, and black-white). Amazing how we can perceive our world in only a few colors and with the help of only three types of cones. Another interesting thing I found in this chapter was the afterimge, a visual image seen after the stimulus has been removed. Lest interesting was the topic of hue, the chromatic aspect of color; saturation, the chromatic strength of a hue; brightness, the distance from black in color space. Why I found these least interesting was I've dealt with them before.
Probably the most important thing with dealing with sensation and perceptions is the fact of the theories of color vision. As color vision is such a key thing in our daily lives.
Terms: hue, saturation, brightness, cones, afterimage, trichromatic theory of color vision, opponent color theory, sensation, perception, color space,
Good deal. I like how you've found the relevance to your own life and interests. Hopefully it will inform your work and art in a positive way.
After reading this chapter, I realized that there was more to color perception than simply memorizing ROY G BIV. In fact, I learned that color doesn’t technically exist in the form that we typically think that it does. The objects our eye sees are not actually colorful; instead the color we see depends on the wavelengths of reflected light that the photoreceptors in the retina absorb. Different wavelengths determine what kind of light is reflected. As we talked about in past chapters, the reflected light is received by two types of photoreceptors: rods and cones. When the rods pick up the light, then there is typically little color variance, this is also known as problem of univariance.
The cones are the main source of color. There are three types of cones, S-cone, M-cone, L-cone, each detecting different wave lengths and eventually perceiving the light as different colors. These cones combine and work together to form different combinations of colors. In fact, the book says that the photoreceptors can tell the difference between 10,000 different colors. In addition to deciphering colors, the cones are also responsible for the three dimensional aspects of color, or color space. Color space is used because it discriminates between different variations of the same color. Color space focuses on the hue, saturation and brightness of each color. Hue is described as determining the most colorful part of color, or I think to think of it as the amount of vibrance in a color. The saturation depends on the amount of the hue that is present. There are typically two scales of saturation, white balance or a incredibly vibrant color. Brightness is the intensity of the light. It looks at how we see colors at night and how it differs from day. This is because at night time, we see what we expect to see. With this logic, if I had been in my room and I knew the walls were red, I would see them as red even though they never were in the first place.
The most interesting point I found was that the ability to see color is perceptual. This theory is called Trichromatry, which states that how we see color depends on the visual system. With this logic, I’m curious as to what other people see as color. Are different color interpretations different between different individuals? Does my blue look like your blue? These are interesting questions that would be tricky to test. This is a relatable topic because it will relate well with today’s American society. With so many people using photoshop or editing pictures will appreciate how the chapter goes into detail about the 3 cones because gives more insight on how to edit specific pictures.
Terms: wavelengths, problem of univariance, s-score, m-score, l-score, photoreceptor, cones, rods, retina, hue, saturation, trichromatry, visual system, brightness, color space, color, visual light, univariance.
I think we do not really see color the same way. Even in non-color deficient humans, there is genetic variation in the opsins that code for the photopigments for each cone type, leading to different spectral sensitivities for each person based on this. Thus the 540 nm light that looks "green" to you, might look like a different hue of green or "greenish-yellow". You could test this. See what kind of opsin the person has for each photopigment for each cone type and then plot their spectral sensitivity functions for various colors that you show them.
Three things from the chapter that I found interesting was the section about the rods and cones, the section about seeing color the same way, and color vision in animals. The section about rods and cones was interesting because it gave us further information about things we already knew and gave us a more in depth knowledge of the subject. Rods are sensitive to low light levels. These low light levels are called scotopic light levels. These are light intensities that are bright enough to stimulate the rod receptors but low enough to not stimulate the cone receptors. In contrast to that, photopic light levels are those that have enough intensity to stimulate the cone receptors and not the rod receptors. Thus, rods are all made to have the same sensitivity to certain wavelengths. Although it is possible to determine a light from a dark object, it is hard to discriminate colors when it is really dark outside. This is due to our rods. Cones on the other hand come in three different types. There are S-cones, M-cones, and L-cones. S-cones or short wave cones have a peak of sensitivity at 440nms. M-cones or middle-wave length cones only have a sensitivity peak of 535 nm, and long-wavelength cones have a sensitivity peak of 565nm. Because of these three cone types, we are able to distinguish the differences in light.
The book outlines the section about seeing color differently in a really interesting way. It comes from all possible angles and gives an explanation about if it could be true, maybe true, and false. If one was to say that yes, it is true, that people see color the same way. They could say it was because usually when there are two lights that look very similar, than those around you are able to be more tempted or able to agree with you. Also there may be some variances in this issue. Depending on your age, you may disagree but this is just because as we get older, the lens in our eye becomes yellowed. If you were to say that no, color is not perceived the same way by everyone. Your reasoning would be because males, in particular, have only one X chromosome. If this X chromosome is damaged than the male will be color blind. Females on the other hand have two X chromosomes, so if one chromosome gets damaged, this will not inhibit their color perception abilities. If someone is a deuteranope, this means that they suffer from color blindness because they do not have any M-cones. If they do not have any M-cones they will be unable to see “green” and redish orange”, the light frequencies associated with the M-cone outputs. If someone was a protanope, this means that they do not have any L-cones. A tritanope is someone without any S-cones. These types of issues would deter a male or female’s ability to see color and there for answers the question and gives evidence to say that not everyone can see color the same way. If you were to say that it maybe possible to see color the same way, your backing would be the color terms across languages. This brings into effect the idea of cultural relativism. This means that basic perceptual experiences may be determined in party by your cultural environment. But speakers of different languages have different terms to describe red, blue, green etc. but they divide the actual physical “color” by light and darkness.
Color vision in animals was also really interesting to read about. The importance of color is so key to so many animals. Evolutionary theory tells us that color is important for looking for food, or else why would it be worth our time to be able to see different colors? Color is also used in cases where flowers emit wavelengths in colors that humans cant even see or the colors of fish and birds as a sexual selection process. Even fireflies and other animals that are able to produce something called bioluminescence can use color to communicate.
I really didn’t find anything the least interesting. The only downfall that I thought about this chapter was that it was so lengthy. They did do a good job at trying to keep you drawn to the text by inserting animals, color graphs, and other pictures. The most useful thing I found in this chapter was about the rods and cones. I found this to be useful because it was something that was covered in Chapter 2 and was now being explained more in depth in this chapter. I would like to know more information about opponent processes.
Terms: opponent processes, rods, cones, scotopic light, photopic light, S-cones, M-cones, L-cones, deuteranope, protanope, tritanope, cultural relativism
It would be strange to not be able to perceive various colors, but also I think that for humans in a mainly artificial environment, the color deficiency issues are not a huge problem for us. It seems like it would make appreciating aesthetic qualities of certain stimuli rather difficult.
For chapter 5 I found the information on additive color mixture to be interesting. This topic was interesting to me because I enjoyed learning about how we perceive light from different wavelengths as one color. I found the example in the chapter to be really interesting because if we were to just look at the picture the man’s face looks to be one color, but when we look very closely at the image of the face we can that there are many different colors used on the man’s face. We just perceive the color to be one and not many.
I also found the information about colorblindness to be interesting. This was interesting to me because it is very rare for someone to be truly colorblind. It is more usual for someone to be missing a set of cone receptors in the retina (like the L,S, or M cones). The L, S, and M cones are used to perceive light. Although someone may be missing one cone receptor they will have the other two, so they are not truly colorblind. To be truly colorblind someone would be either cone monochromat (where they would only see gray) or rod monochromat (where they would find it difficult to see in daylight.)
Another topic I found to be interesting was if everyone sees colors the same way. What I found interesting about this was the cultural relativism. Although people’s cultures may be different in defining color research shows as long as there in not a deficit in the color vision than everyone does see the same colors. We may not describe them the same way or have the same words for a color. We all for the most part can distinguish the difference in two colors. I also found it interesting that we really can perceive about 10 million different colors.
I found the information on hue, saturation, and brightness to be least interesting. This was the least interesting to me because it seems to be a lot of information going back and forth. This made it a bit confusing. The chapter made it seem harder to understand than what it really was.
What I found to be most helpful in understanding sensation and perception would be the information on the cones. Most importantly the L,S, and M cones. I found this to be most important because it is how we “see” different colors, and they deal directly with our color vision. And without these cones we would not perceive color the same way. Although our brains fill in some of the information about colors, the cones are important in perceiving color.
I would like to know more about additive color mixture because I find it interesting that we perceive may colors to be one. I would also like to know more about anomia (the inability to name colors) because I also found this to be interesting because it is abnormal and is something we really do not hear about.
Terms: additive color mixture, cone receptors, retina, L,S, and M cones, cone monochromat, rod monochromat, hue, saturation, brightness, cultural relativism, anomia
Its strange, because what we view as anomia or a deficit in naming colors, others might view as normal. In some countries where tribal communities are prevalent, there are only a few color categories. Some only differentiate by luminance (light or dark), and some only have a red and then everything else. So you might ask a person from one of these places to name a green object, but they might not have a name for it. But does this mean they are unable, or just do not have a need to differentiate between the two based on their culture? Interesting.
Additive and subtractive color mixture was the first thing that caught my eye (sorry, bad pun) because it added to what I already knew. I knew that different colored lights shining onto different colored surfaces would still only reflect the light wave that would be reflected with white light. But I guess I just never thought of it in math terms before when it came to adding and subtracting colors from one another when being combined and reflecting off a surface. The second thing I recognized was negative afterimage. I like learning about things that I can relate to something I have already experienced like afterimages. I’m quite sure that at some point a teacher in high school had us playing around with negative afterimages. It was a lot of fun since anyone can do it and experience it. When I was reading about hue, saturation and brightness I started to wonder if females are more sensitive to these then males? My reasoning for this is that in my parent’s house, my Mom is the one who tries to have things match when decorating. While my Dad (who does care) does not have the same reaction to things as my Mom. He may think something along the same lines but he won’t bother to really go out of his way or be bothered by it enough to want to change it. If looking at it from a stereotypical viewpoint; women tend to go for things that have lots of colors that please them (my Sister and I) while for men color just happens to be an accessory to the thing they want (my Dad and guys I work with).
The section on Opponent Processes: Repackaging the Information (page 114) and Opponent Processes: Opponent Cells in the Lateral Geniculate Nucleus (page 115) I didn’t find to interesting. I just felt like it was just a review of previous information from earlier chapters.
How we perceive color from wavelengths and how those wavelengths can be changed/manipulated. We see our world in color and rely on it for so many things like knowing when a light it red so we know when to stop. Animals and plants use color all the time for survival and mating. Like the Poison Dart Frog. They are cool to look at because they are an assortment of neon colors that you don’t usually find on animals. But those colors hold a very specific purpose, they say “Don’t even try to eat me, I’m covered in poison!”
Achromatopsia and Color-Anomalous. I’m more curious about how many people have these conditions and if any research is looking at how to revers them.
Terms: additive color mixture, subtractive color mixture, negative afterimage, hue, saturation, brightness, wavelengths, achromatopsia, and color-anomalous.
It's interesting because the differences between men and women might actually be based on the different opsins that code for photopigments in the cone types for males versus females. This means we could have different spectral sensitivity functions that allow us A) to have a different experience of color B) perhaps value it differently or have different preferences.
Out of the gate I was interested in this chapter because it started with a section that laid out the basic principles of color perception. The information was not especially dense in this section so it was very easy for me to grasp what was being explained. This section discussed the absorption and reflection of light. As I already knew the color of something whether light or dark depends on the amount of light that the surface absorbs. What was interesting to read in this section was how it was stressed that wavelengths don’t have color. The example used was a statement that said “there is no red in 700 nm of light, just as there is no pain in the hooves of a kicking horse”
Next came the question of whether or not everyone see color the same way. This was interesting to me because the answer ended up being yes, no, and maybe. How can that be? When the answer is yes it is because people generally agree on matches of metamers. When the answer was no, the book began to talk about color blindness. I then learned that there were a number of different types of color blindness, one for each type of cones a human has. For individuals who suffer due to the m cones they are called a dueteranope, l cone are protanope’s, and s cones are tritanopes. Cultural relativism played a big role in the answer being maybe. It assumes that the cultural environment may be able to somehow influence everyone to perceive colors the same way.
Color constancy was also pretty interesting. It was cool to read about why things remain the same color to us even when the illuminant is different. This is possible because we are able to discount the role that the illuminant plays. I think that we would all be in a world of hurt if we were unable to do that. Although I wasn’t really able to grasp how spectral reflectance function and spectral power distribution were being explained I know they play a pretty vital role in all of this.
Afterimages were not that interesting to me. These images are what is present after a stimulus is removed. I would say that for the most part I was uninterested because I did not really know how to do the interactions with the figures in the section. I always look forward to doing those and I didn’t understand the ones on afterimages.
What I believe was best for my understanding of sensation and perception was understanding what color vision really is. The book states color vision is strictly a mental phenomenon and not a physical one. That is essential to understand because it indicates that the mind is interpreting something in a different state than what it’s really in. In this case it is doing for good reason. By being able to interpret things into colors people and animals are able to more easily identify things that are essential for survival. On the flipside of that colors can be clear indicators of potentially harmful things also. Although I do not believe in full out evolution this phenomenon really makes me think.
The two concepts that I would like to know more about are the spectral reflectance function, and also the spectral power distribution. I would like to know more about these because the color constancy section was probably the most interesting section to mw overall. I know that these two things play a part in that and I did not quite understand how.
Key terms: cones, color blindness, protanope, dueteranope, tritanope, metamers, cultural relativism, color constancy, spectral reflectance function, spectral power distribution, afterimage
I think these points not only tell us about color perception, but about how the brain actually works. It has a lot of problems that it is faced with that it has to overcome in order to carry out certain functions for our safety and survival. Mechanisms like object constancy, color constancy, etc. are all pretty amazing given that the environment changes our perception so rapidly with something as simple as the presence or absence of photic energy.
First of all, I surprisingly enjoyed the segment about the three-dimensional color space. It was not particularly deep or anything but I liked how it described color vision in a way I had never thought about before. We have all grown up messing with the knobs on our television sets and have a pretty intuitive idea of what hue (the chromatic aspect of color), saturation (chromatic strength), and brightness (distance from black) are. However, I had never really thought about this relationship specifically as a three-dimensional relationship before - it may seem a bit silly, but I thought this was kind of neat.
I also thought the relationships of wavelengths and how they are perceived was well articulated. Too often we get caught up in classifying the trichromatic receptors as "red", "green", and "blue" - I thought driving home the fact that they are S-, M-, and L-cones was a very important distinction to make. The description of additive and subtractive color mixtures was also extremely easy to understand - it is still a bit mystifying how green and red light mix to form yellow given my own personal experience with fingerpaint, but I much better understand the mechanisms behind these mixtures than I did before. I think the least intuitive part is that differing wavelengths average themselves out into metamers when combined, however this is far easier to conceptualize when using an analogy such as the pointillism movement of Postimpressionist France.
I also enjoyed the section on illuminants a great deal, if only because it caused me to think more than any other section of this chapter. Color constancy of an object remaining unchanged despite changes in the environment is a bit difficult to wrap my head around right away without having some sort of active demonstration, but the book did a fairly good job of describing this concept relative to spectral reflectance and spectral power.
The section I did not like was the portion on color vision in animals. This was not because it was uninteresting or anything, but merely because it only grazed the surface and did not provide much substantial knowledge to do anything more than merely pique my interest. I would enjoy learning more about color constancy and achromatopsia in class.
Terms: three-dimensional color space, hue, saturation, brightness, trichromatic, S-cone, M-cone, L-cone, additive color mixture, subtractive color mixture, metamer, color constancy, spectral reflectance, spectral power. achromatopsia
Good points. It does make you think about this stuff in a different way once you learn about it.
There were many things within this chapter that I found both useful and interesting. One of the more interesting subjects was cultural relativism, which is the idea that basic perceptual experiences may be determined in part by the culture environment. The example of the book gave two different types of choices between different colors. I enjoyed this because I remember once taking a quiz with very similar questions that let you know what career would best fit you based on your favorite color. The second item I found to be very interesting was color vision in animals. I loved the example the book gave of the two pictures that showed the strawberries. One of the pictures was in color whereas the other was in black and white. Just by viewing that example made me realize how vital color is for humans to have survived and evolved over time. Another item I found fascinating was color constancy. Color constancy is the tendency of a surface to appear the same color under a fairly wide range of illuminants. I also enjoyed reading about the lateral geniculate nucleus or otherwise known as LGN. The LGN is a structure in the thalamus that receives input from the retinal ganglion cells and has input and output connections to the visual cortex. Some information that I found to be the least interesting was the information that dealt directly with the hue of a certain colors. I understand the importance of why colors have a certain saturation and brightness to them however I find that information the least interesting. I think the two most important items in this chapter that will help explain the perception of color in greater detail is if everyone perceives color the same way and also explaining the wavelength of light. The spectral reflectance function seems very interesting and important as well. The two items I would like more information about would be if people perceive color the same and also animal color vision.
Terms: Cultural relativism, color constancy, lateral geniculate nucleus, retinal ganglion cells, visual cortex, hue, saturation, brightness, spectral reflectance function.
See above comments I made on other people's posts for the differences in the phenomenology of color perception. There are a variety of species that can see and not see certain colors. I took a class from a color vision expert who has tested squirrels, dogs, cats, monkeys, dolphins, sea turtles, all kinds of animals for color vision. Pretty amazing stuff. Different types of sea turtles are more sensitive to certain colored light, and fisheries for years used a certain light to attract certain fish and shrimp into their nets and hooks. So this study this professor I had did involved them identifying what colors the turtles were least sensitive to so that the fisheries could use these colors so as to not attract the sea turtles (who are endangered). Pretty cool stuff.
When we consider color that we visualize it seems rather simplistic, but chapter five includes the underlying information of the perception of color in a more in depth and complex way. When I started reading this chapter the first thing I noticed was the moonlight picture of figure 5.3. We have all experienced a dark night with a brightly glowing moon, it appears that everything is colorless around us, we are unable to discriminate wavelengths and we see no color. If we think back on the retinal level we are able to understand that the retina is light sensitive. The retina is located in the back of our eyes and includes rods and cones. Rods and cones are two essential types of photoreceptors important for vision. Photoreceptors are light sensitive. One photoreceptor, rods, is especially important for allowing us night vision. The other photoreceptor cones, help us to depict color, light, and visual acuity. In terms of trichromacy both rods and cones are sensitive to scotopic light levels. Scotopic activity refers the ability of rods to become stimulated by these light intensities but unable to stimulate cones in the same way. Rods and cones are part of a duplex system. This means that humans use both cones and retinas that function in differing conditions. It is possible to distinguish light and dark when considering this scotopic state, yet we are still not able to identify colors. The wavelengths that allow us to see color during the day when it is light out does not have the same effect at night under a dim moonlight. There are three types cones we can use to further conceptualize the trichromatic theory of color vision. S-cones are shortwave lengths, M-cones are medium wave length, and L-cones are the greatest wave lengths. Each one of these peaks at a capacity. Color is shown and we are able to determine differences between light and wavelength but S-cones and L-cones produce a different output and give us a different response for the cone types. I also found it very interesting about the idea that three numbers can produce such a wide array of various color images. Color space helps tell us that in this three dimensional space is due to the three cone types: S-cones, M-cones, and L-cones. These help us to identify sets of colors. When we compare colors we are able to notice mixing colors produces a whole new color. Say for example we combine the two colors of red and green we get a yellow color. Using darker and lighter shades of the original colors makes a hue. The various color shades are also attributed to saturation. White is the very least saturated color, while green is much more highly saturated. Furthermore, light intensity is attributed to brightness. The greater the light intensity the brighter the color, while less light intensity induces a lower level of brightness. One other concept sparked an interest was how or whether we all see color the same. There are exceptions for certain people that don’t allow them to visually depict color like the general population. Achromatopsia is one example, because this condition stops individuals from seeing color due to some injury that has harmed the brain or central nervous system. In other instances some people lack one of the three cone types. For example someone who has protanope means they do not have the L-cone. I find it interesting that there are exceptions to color vision and many instances may be genetic. Probably the most commonly thought of distortion, or lack of color availability is seen in color blindness. The thing I found least interesting was probably the section on unrelated and related colors. It is interesting because of how we get brown or gray, but there wasn’t a whole lot of information on this topic. The most useful information from the chapter was all about trichromacy and the importance of rods and cones and how we see or don’t see color. I believe the important details are the most important to learning sensation and perception because of how detailed and complex they are. Two concepts I would like to learn more information about include agnosia and anomia. I find these two topics particularly interesting because it doesn’t entail information about how we recognize or name objects, but reveals to us how certain people are unable to instead.
Terms: retina, photoreceptors, rods, cones, scotopic, duplex, trichromatic theory of color vision, color space, hue, saturation, brightness, achromatopsia, protanope
Typically some area of visual cortex, probably near or within V4, gets damaged and the result is intact retinal catch of the various wavelengths, but no way to process the information once it gets to the cortex. Fascinating acquired color deficiencies.
I thought this chapter was really interesting in that I was never aware that color does not really exist. It is always described as a physical property and that is always how I have thought of it as. Color is actually just a small part of the light spectrum that we are able to see. There are three main types of cones we use to see color: M,L,S. M-cone is primarly used to see blue color, L-cone is primarly used to see red, and the S-cone is primarily used to see green. These cones are particular to each color because they are most senseative to the frequence that each travels at. However, your sensativity to light is not that easily explained. Rods also play a part in your ability to distinguish color. They are more senseative to low levels or whats known as scotopic light levels. Colors can also be added or subtracted because of mixture of lights and pigments. These are whats known as the additive and subtractive color mixtures.
Another thing that I thought was interesting is how relatively common colorblindness is. I have heard of it before reading this chapter, but was unaware that 8% of men and .5% of women have it. I thought that maybe 1/300 people had it. I also thought it was interesting that not all animals see the same way as humans. I had just assumed that animals see the same way as humans, but with different levels of quality. However, not all animals are trichromats as humans are. My guess is that animals (like humans) have evolved over time to get the levels of vision necessary for survival.
I find it interesting in learning how we precieve color because a very thought prevoking topic. However, being such a relatively new idea to me and such a conceptual idea, I did find it difficult to understand the chapter. It took a few readings to get a decent grasp on the chapter and even now I still need some clarification.
Terms: Cone, M-cone, L-cone, S-cone, Rods, Scotopic, Additive color mixture, Subtractive color mixture, trichromats.
The strange thing about color blindness is that people who have these color deficiencies can still see some colors, it just depends on what cone type they are missing. If they have acquired colorblindness (achromatopsia) that might be a different story, but it all depends on the extent of the damage.
First of the three things that I found interesting from this chapter is the cones. There are three types of cones in the eye, the S-cone (blue cone), M-cone (green cone), and L cone (red cone). These cones are the primary reason we see color, and without any of these cones we would be seeing things in a colorless black and white setting. It is amazing how complex our vision is and how much we take it for granted. The second thing I will remember is color-anomalous. Color-anomalous, or better known as color blindness, according to the text affects these individuals because typically they have three cone pigments, but two of them are so similar that these individuals experience the world in much the same way as individuals with only two cone types. The reason I thought this was interesting was because after reading about the cones I thought it was neat to see how the cones are affected, thus causing color-anomalous. Lastly, I thought anomia was kind of interesting. Anomia, according to the text is an inability to name objects in spite of the ability to see and recognize them. They say that this is typically caused due to a brain injury. I thought this was interesting just because I have never heard of it before so I just found it interesting.
The thing I found least interesting was the section about the opponent process. I thought it was boring, dry, and a little to all over the place. This section had me lost and confused. Something from this chapter that I think will be most useful in understanding sensation and perception is knowing about the cones, and the different disorders dealing with those cones. Two topics I would like to know more about is anomia, and agnosia.
Terms used- S-cone, M-cone, L-cone, color anomalons, anomia, agnosia, and opponent process.
The opponent channels are a bit difficult to wrap your head around at first pass. Think of it like this. Can you see a reddish-greenish hue or color? Can you see a bluish-yellow? Not under normal states of perception. This is the basis of the color opponency and the color axes in color space.
The perception of color is a unique topic altogether. It is very intriguing to learn about how we truly perceive color and all the fundamentals that come with it. For instance, color is based off of three types of cone photoreceptors, also known as color space. When I think about seeing color, all that comes to my mind is oh hey, I recognize that color. I don't take the time to realize that it actually has to go through processes to get to our retina, such as the hue, saturation and brightness. The hue is light, saturation is the process of the hue and brightness has to deal with the intensity of the light.
I knew of people being born color blind but I had never heard of somebody becoming color blind due to a head injury, which is called achromatopsia. This makes me think of all the times I was younger and how many bumps and bruises I got on my head. I am very very very fortunate that I have not lost my color vision and that I can see colors. I'd be sad if I couldn't see.
As Otto mentioned today in class, when we see the light coming through a window and reflecting on a wall, we know that the wall is still the same color, even if the light is making it look a different color. This is also known as reflectances, which deals with the precentage of light that hits a surface.
Everything in this chapter was educational and interesting to learn about. This chapter was an easy read and it all related to sesation and perception by the way that it described the retina, how we perceive colors, the different rods and cones that are used to affect the process, the wavelengths, and more things that contribute to it. I would like to learn more about animal color and why certain animals don't see color and others do.
Terms: color space, photorecptors, retina, hue, saturation, brightness, achromatopsia, reflectances, rods, cones.
Pretty amazing and intricate process to understand how it even works. The crazy thing is that we have to learn about this stuff that our brain does naturally for us all the time.
First of all, the most interesting part of this chapter was how our cones obtain specific wavelengths and convert that into something we perceive constantly every day, color. Color can’t be perceived by one cell, or only one type of photoreceptor. Instead color receptive cells need constant communication between each other to pinpoint what specific wavelength is in the environment. This is due to the retinal cells being categorized into three types: L-cone, M-cone, and S-cone. They each are more adapted to different heights of wavelength; long, middle, and short (respectively). When a wavelength is presented to these cells, the corresponding excitement from these three types of cells pinpoints the specific color. If only one type of cell was used, there would be much more confusion and errors in the visual processes. This theory of vision, of having three different types of photoreceptors, is called that trichromatic theory of color vision.
Secondly, another topic I was interested in was how our color visual system responds to a changing environment. As discussed in the previous paragraph, the color visual system seems fairly simple. However, this is mostly due to a generalized concept of the outside world. In the natural environment, there are many different wavelengths at once, and they blend together. Also, objects change color throughout the day, how do we perceive an object as the same color? First, why do we perceive a single color, when we know some of them are just a mixture of wavelengths? These are called metamers, and they work just the same as individual wavelengths. If you mix a red light and a green light, you will perceive an effect of a yellow light; this metamer is slightly different than pure yellow light. The red and green light will stimulate the photoreceptors in the same ratio as yellow light would. Even though pure yellow light is physically different in the natural world, we perceive it as the same as a metamer.
Another part that I was interested in that relates to the color visual system in everyday life was color constancy. As we go throughout our day, the color of objects changes fairly rapidly. Through the sun setting, or turning on different lights in your house, different wavelengths are being introduced to your visual system; even from the same object. While looking at an apple, you may notice that it is red; however, if somebody turned a blue light on in the background, the apple would emit a different wavelength. You may notice that the apple looks more blue, but you would still describe the apple as red. This is called color constancy, and this is due to the blue light in the background being emitted into your entire visual system, and your brain will account for this environmental change.
My least favorite aspect of this chapter was the history of the trichromatic theory. Even though it serves a purpose, I personally am not very interested in history. As you may have noticed in my previous posts, I am more interested in conceptual ideas and the anatomy and physiology of the sensory systems.
Terms: photoreceptor, L-cone, M-cone, S-cone, trichromatic theory of color vision, metamers, color constancy
I was really excited and curious when I figured out what this week’s chapter was about because it is difficult to fathom the idea that color exists only when our brain and eyes work together. The sentence I found most important for my understanding of sensation and perception was on page 105 and says, “like pain, color is the result of interaction of a physical stimulus with a particular nervous system.” This helped me to understand this idea a little better by relating it to something pain, which I understand because of Health psych. Since I enjoyed most of this chapter I am going to begin with the tiny thing I did not like because in reality most of it interested me. On page 118 figures 5.15 there was an experiment where you had to look at a dot in the middle of a circle of dots and switch back and forth between the one with colored dots and the one with grey dots. The colored ones were suppose to make the grey ones turn colors because of negative after image. I could not get this to work and it was frustrating! I have seen similar experiments to this and I have generally gotten good results so I am not sure why this happened.
I had a plethora of information that I enjoyed about this chapter. The part that stands out most was pages 119 and 120 because I had been wondering about this question since the first day of class! Since our brain creates color it seems to me that all people would see it differently but then again I could see how this could go both ways. In psychology we learn about how many people’s memories have similar properties and their language develops in the same way so it makes sense that people could have the same perception of color but it just seems as if this could easy go the other direction for the same reason only different examples. While people have the same physical make up their individual parts differ greatly which is why I thought it could be the same case for the perception of color. Funny though, the book did not really have an answer to my question, research has shown that MAYBE people see colors slightly differently but much of what we see is the same, colorblindness being one of the exceptions.
Closely related to this idea of color perceptions and the similarities within it is the concept of color constancy. This has to do with illumination of light on a surface and how our cones perceive the color. Although the light is being reflected in different ways we still see it as the same color, thus we have color constancy. This helps us because when things in nature stay the same we can recognize them and concentrate on other parts of the environment that may be of danger or changing so that we notice them.
While I was busy being curious about humans and how they see color I had not even thought about how animals see color, so I was delighted when I came across this section. What is believed and accepted within the scientific community is that an animal’s ability to see color is linked with their need to eat certain types of food and sex. This makes sense because passing on DNA and eating to survive seem to be the most important things in the animals kingdom (even to us humans really). Thus, animals see colors because this allows them to find a mate of a particular sex which in turn creates off spring and an animal sees certain colors because this means that the food is of some nutritional value to them.
Terms: negative after image, color, colorblindness, color constancy, illumination, and cones.
Chapter 5-objects and scenes After reading chapter 5 I really found the following three topics to be interesting; distinguishing objects from background, good continuation, and global image features.
Distingushing objects from a background is more difficult to see like the Rubin’s test of reversible face-vase figure. The technical term of this is perceptual segregation that separates one object from another. A figure stands out from a background in or environment and the background is like the “ground.” A thing like object is more memorable because it stands out. The diagram shows a white vase in a blue background, but the background shows two faces on each side of the vase to make the shape of the vase. This is interesting because this happens in my life when Im looking at objects or artwork. It was nice to understand more on this topic and why it stands out because we perceive may stand out or symmetrical objects may play a role. The second topic I found interesting is the good continuation.
The law of good continuation points that when connected we perceive the object either it is straight or curved. The Celtic knot pattern in the book is an example where it looked interweaved but it doesn’t look broken. An everyday example would be my headphones to my ipod and my headphones for my computer are laying together they could be overlapped but good continuation helps us perceive two separate wires. This made sense to me because I have personally experienced good continuation.
The third topic of global image features is interesting because we consiously break up scene in categories. There are categories or naturalness of a scene, openness, roughness,expansion, and color. We can perceive a scene by understanding textures and visibility, smooth scenes, distance, and colors. When I am in my environment I do not consider these categories until I read this part of the chapter. Now when I have been to the lake or in the outdoors, my perception does know how to describe these specific scenes.
The one thing I did not enjoy reading in this chapter was the physiology of neurons responding to grouping and figure ground perception. It was hard to understand exactly how the neurons work to respond to objects in a scene in our environment. The wording was a little to medical/technical. I would need to do a hands on example or video to completely understand this process.
The most useful information in this chapter was computers are unable to match persons ability of perception. We have all this technology in today’s society, but nothing can compare to how humans perceive. The beginning of the chapter explains that robots are made but there are obstacles that machines cant recognize or distinguish like the human perception.
The two topics I would like to find more information about is robotic engineering of perception and reading or conducting an experiment using Gestalt’s laws of heuristics to the best-guess solution.
Chapter 5 in my book is titled the Perception of Color.
Throughout this chapter, I found several things to be very interesting. I didn't fully understand everything, but I was definitely interested in learning more!
I liked learning about trichromacy because it was a complex way of looking at color based on light. I learned that we see minimal color at night because of this idea of trichomacy. Relationships between the wavelengths help to distinguish what can be seen. I found this interesting because I haven't ever thought about the differences in colors between daytime and nighttime. I always thought this was just the way it was. I didn't really understand what this meant but it is cool to know that there is science behind this difference.
I liked learning about the perception behind things I have known before such as saturation and brightness. My fiance is a photographer and he has taught me the photographic way of looking at these things. I thought it was super interesting to look at color from the point of view of a psychologist. Saturation is how much true color is present within the light and brightness is the intensity of that light. I really would like to look into other terms that we associate with pictures from a psychological perspective.
I really enjoyed the part of the chapter that talked about if every individual sees color the same way. Within this section, I learned about several different disorders that can cause people to see color differently. On of which was color-anomalous or color-blind. I truly thought that there was only one difference in peoples perceptions of color and that was color-blindness. But I was wrong. Our chapter talks about at least 7 different types and I never knew any of them existed. I hope to learn more about different "color disorders" and that is why I chose to do my topical blog on this subject.
I did not enjoy learning about the history behind the theories about color. They were not interesting to me at all. I was struggling to know how some of the theories worked and I wish that would have been explained a little more throughout this chapter. Even though I thought the theories were the least interesting, I would presume they would be what is most important to sensation and perception and relating it to the rest of the chapter.
Trichromacy, saturation, brightness, color-anomalous