FINAL BLOG ENTRY

Constancy

So we’ve discussed multiple forms of constancy. Most recently, color constancy and lightness constancy. This has been a theme throughout the semester, as more often than not, each sense has had a constancy system built into its perceptual procedure. I’ll start off with a quick background with a few of the constancy properties we’ve discussed and read about, and finish with some possible reasons and explanations for this seemingly ubiquitous phenomena.

First, odor constancy. Odor constancy is defined as “the perceived strength of an odor remains constant despite variation in flow rate” (527). As I’m sure we all remember, sniffing helps draw the air up into the nostrils, giving a greater number of smell molecules a chance to be perceived. Therefore, sniffing increases the number of molecules floating by the detectors, but it does not increase the perceived experience.

Next, form constancy which has been explained as the ability to recognize objects despite changes in their 3-d rotation and configuration. (Ch 5 text). This leads to our ability to recognize shapes from different angles and the task of determining size and magnification. Without form constancy, we’d have to have a different representation in our brain for every possible setup of configuration for an object.

Most recently, we’ve discussed color constancy, which is “the name given to [the] propensity of an object’s color to remain constant despite changes in the spectrum of light falling on that object, and thus changes [in the] the light reflected toward the viewer from the object.” (245) The book gives the example that green grass always looks green, and yellow roses are always red. This type of constancy results from different properties of the eye, from light adaptation (which we studied earlier in the semester) to color induction. Color induction is when the “eyes adapt to the prevailing light condition” (245). A great example is when you wear reddish tinted sunglasses and when you take them off, the world looks really weird for a little bit. The book refers to this as when, “preceding color stimulation or . . . the presence of other colors elsewhere in the visual field” influences the current color appearance.  I think I’m rambling now, but you get the point. The visual system has many checks and balances that allow for constant perception of vision, keeping the perception as stable as possible in a  possibly wildly fluctuating world.

Last, and real quickly, is size constancy. It is defined from the book as “perceived size is scaled in terms of perceived distance” I’ll help explain this with a picture:

So heres just an animated version of the example we saw in class, but it moves and it drives me nuts. I even did a print screen to make sure:

The object looks bigger, because it is perceived as being farther away. Its retinal image is the same size as the object that is closer, so it must be larger than the closer image. So thats size constancy. This took a bit more space than I had anticipated, so I’ll wrap it up quickly.

There are all kinds of constancy, but why have they evolved? Well apparently its advantageous, because its involved in both smell and in several forms of visual processing. I’d like to think that constancy helps make understanding the world a bit easier. I mean, the world is already an incredibly complex place, just go out and take a look at how many things you see in your visual field, and how many molecules are floating around in the air. Constancys make the job of the brain a bit easier by taking shortcuts and not processing all ridiculous possibilities. What if I had to incorporate how hard I was sniffing and factor that into the amount of smell, and then make a decision; by that time the dangerous smell could have already killed me. The job of perception is to “put us in contact with the word we live in; it shapes or knowledge of that world, and knowledge is power. Our chances of survival improve markedly if we can detect object and events in our environment and if we can, then, distunigish safe from the dangerous.  Knowing about our world allows us to predict the consequences of our action, a critical skill in a constantly changing world.” (1) Sounds to me like constancys are a critical part of perception, as they are essential tools in the acheivement of perception.

Color Filters

I first want to start out by showing this really funny video I stumbled upon while doing some background research.

You can watch the whole thing, but it basically starts to get good at the 1:15 mark.  Both guys only have one eye, and they end up working together to combine their eyes to get depth perception. At the end theres a segment where I think you’re supposed to wear 3-D glasses, but I couldn’t test it and am not sure how well it came out. Regardless, I think its both hilarious and informative during the scenes where they collaborate to achieve depth perception. The obvious effect here from colored filters (the 3-D glasses) is the perception of depth.

I’m going to switch gears a little bit here away from the 3D effects of colored filters, and toward their possible application to help alleviate dyslexia symptoms.

Heres a couple websites that deal with some of their specific findings doing this kind of worl:

http://www.dyslexiaservices.com.au/4.html

http://youtube.com/watch?v=MKfs2nev-mw (an example from the institute referenced above)

http://precedings.nature.com/documents/1729/version/1/html

I’ve got a cousin who is 12 years old and has symptoms of dyslexia, and she uses filters. She has told me that sometimes they help her, and other times they don’t. The nature.com article says, “The selection of colored filters . . . is based on adjustments of saturation and hue of light illuminating the page of text until visual distortions and discomfort are minimized.”  According to our text, Jay Neitz and colleagues suggest, “the visual system assumes that the light illuminating the environment is always broadband “white” light, and when we wear filters that disrupt that whiteness the visual system simply recalibrates the relative strengths from the L, M, and S cones to recover a balance that yields an overall equal response from each cone type.” It discusses how because this process can occur in only one eye, but affect both eyes, then it must take place in the visual cortex. Its possible that by minimizing the noise that the visual system sends along to other areas of the brain, then the other areas of the brain may be able to better accomplish their tasks.

Clearly there in an incredibly complex system with all kinds of signals and noise being thrown into the brain. Color vision is incredibly complex, and as our text shows, new research is currently being done all the time. Especially in the color vision chapters, the text constantly just mentioned new theories, and then just moved along.  It was as if the book did not even know what to make of the wealth of possibilites. Color vision is incredibly complex, and I could write for hours about it, but I’ll end here.

Doppler effect

We’ve recently talked about what causes and constitutes the perception of color. At one point in the discussion, it was brought up that there is not necessarily a property that causes a certain perception of color. It involves the wavelengths of light that are reflected off of the object and are processed by the three different cones. In conclusion, the perception has no direct link to do with the object itself; however, often cases there is an even more separation between perception and reality. In physics there exists a phenomenom known as the doppler effect. The doppler effect is caused by objects in motion either away or toward the observer, and this motion causes changes in the wavelength of the light coming off the object. Here in our daily experiences we see this most often with sound waves, as a firetruck comes close to us its siren increases in frequency, and then decreases as it passes and goes away from us. Here’s a quick explanation of the effect:

This effect, however, also can be applied to the perception of light. Granted, in order for the doppler effect to have a significant effect on the wavelengths, the objects must be moving at incredible speeds. So I want to apply this to our perception of the universe. While images are taken of very distant objects, the perceived object has a characteristic wavelength of light that it emits. From this information it is possible to determine a lot of properties about far away places. But alas, our perceived data has failed us yet again. As explained in the video, most objects experience a doppler effect causing the redshift.

The reason I’m trying to bring this up is to show just another reason of how the perception of color does not necessarily reflect any direct property of the object. If I were to ask you to describe about a tomato, you probably would describe its color. We take colors as a very real and intrinsic value of any object, yet it is such an indirect link. Granted, we don’t experience high velocity items that may cause a doppler effect in light waves, but it adds to the feeling that color perception is largely due to the setup of the eye than with the objects themselves.

Nature vs. Nurture-ish

I hate the nature vs. nurture question. It drives me nuts; the answer always is both! So rather than trying to off an explanation of one over the other, I’m going to take a different approach. We’ve discussed how the visual system develops as it receives information. The reception of information leads to forward information which eventually leads to feedback. So what happens if a person never gets those initial signals. What if a blind person never got any signal from the eyes, so how do those areas of the visual cortex develop?

The reason I ask is I’d like to compare the possibility of some sort of implant similar to the cochlear implant. Is it possible to place some kind of signal into, for example, the LGN and will this stimulus pass through the visual systems as it does in a normal person. I’m no expert, and I’m sure some advanced research is going on at this point. However, I’m going to give it a very elementary examination with some information that I could gather in jsut a few web searches.

So if this actually could happen, would the upper level visual systems no what the heck these signals are? Is it possible to bend nature to accept this new response? I think its pretty intriguing. I want also to suggest that the brain systems would not accept this signal, because sometimes they are used for other things. For example, http://query.nytimes.com/gst/fullpage.html?res=9C06E2DD153BF930A1575AC0A961958260 says that visual systems are used in other tasks, if they don’t receive any signals. So suddenly, the question of whether nurture can bend nature becomes relevant, and theres no doubt: as technology progresses, so will our ability to create perceptions for those who can not naturally perceive.

Trickery

I’m a huge fan of sports, and I can’t tell you how many times I’ve seen trick plays attempted. A trick play in any sport is when you try to deceive your opponent that you’re doing one thing, but in reality you’re going to do a completely different thing. Since we’re in the middle of March Madness, I’ll start with a basketball trick play. Keep an eye on who is inbounding the pass and where everyone else on the court is.

I love this trick. So at half-time you switch sides, so the team inbounding the ball would line up under the WRONG basket going the WRONG way. The defense would not notice this and would also line up under the wrong basket. THen the inbounding team would pass it in and score easily under the un-defended basket. Really they  ought to have been paying closer attention.

Next, the sport where trick plays are attempted much more often is football. In high school, we would run a play where everyone would do a normal activity, except for one guy. One guy would do run parallel to the line of scrimmage and pick the ball up and no one ever saw him do it. The paralell movement of the runner was so strange, that no one ever noticed it. I wish I had a video of it, but man, this worked like a charm every time. It was amazing how a completely out-of-place movement went completely unnoticed by anyone.

I’ll leave you with a fairly famous trick play which was recently voted by ESPN as one of the greatest highlight clips of all time. In this play, the quarterback makes a throwing motion, but then someone else discretely picks up the ball from him and runs the opposite way. Everyone usually is so focused on the quarterback, that no one ever notices the runner. It’s quite amazing that trick plays actually work. It is a testament to how much we really miss when we’re looking at something. Its called the Statue of Liberty play; here’s a clip:

Keep an eye on the Orange player who starts farthest to the left on the screen. Watch as he tries to go unnoticed and takes advantage of the inattentional blindness.

Cortical Magnification

 

Other Eye Balls

At first, I could not figure out why the human eye looked so odd to me. Then I realized it didn’t really make much sense for the light to have to go through all the horizontal cell, GRC, and bipolar cells before it gets to the photoreceptors. So in my quick investigation. There seems to be two distinct types of eyes at first. There are compound eyes consisting of more than one lens and a single lens eye setup. The compound lens is represented by an insect eye and here is an example.

The next distinction is between the vertebrate eye and eye employed by the cephalopod and the squid. The cephalopod eye has the photorecptors in the outermost layer, so the light strikes those first. This seems like it makes the most sense, since it would prevent any scattering by those cells. A sketch of the vertebrate eye on this picture:

Then here is a human eye compared to a cephalopod eye.

The squid eye has the rod cells on the outter layer, being struck first. So I think this reinforces the idea that the you have to understand the eye before you can understand vision. In this study, vision is a slave to the eye, because the eye setup determines what information is made available for vision. Not only that but it determines in what form the information arrives at the brain. Clearly, a study of the anatomy of the eye is essential for a sudy of vision.

References:

http://www.bio.davidson.edu/people/midorcas/animalphysiology/websites/2003/Muller/images/ov2.gif

http://www.bio.davidson.edu/people/midorcas/animalphysiology/websites/2003/Muller/development%20of%20the%20cephalopod%20eye.htm

Cochlear Implants Game

Because the cochlear implants examples didn’t work in class the other day, I decided to try to make a game out of it. The purpose of the game is to match each example, which is what the person with cochlear implants would ‘hear,’ to how many number of channels that example has. The options are 1, 2, 4, 6, and 8 channels. The number of channels represents basically relates the amount of information in the sound, with higher channels containing more information. So try to rank each of these examples in an order of increasing channels. Also, try to pick out the level at which you can think you can reliably understand what is being said. The answers for which examples go with which channels are at the bottom of this blog, along with what is being said in each example. Don’t cheat.

Example 1

Example 2

Example 3

Example 4

Example 5

According to the University Of Texas-Dallas website, adults needed 5-8 channels in order to understand the speech. My first time through I only understood for Channel 8 (example 4). According to one study by Susan G. Fisher, some people with the multi-channel cochlear implants could even understand speech on the telephone, which is remarkable because there is no visual clues from he telephone. In other less remarkable cases, the cochlear implants allowed patients to pick up a word here or there, which allowed them to combine this information with some visual clues. I think that with a lot of practice there definitely could be some remarkable skills in hearing with these devices. Definitely the more I listen to the lower channel examples, the more I pick up subtle sounds which I didn’t hear before. Listening to these examples has introduced me to a very basic form of hearing speech, and the struggle has helped me realize how much information I actually get from me years

Also, on quick side-note, in my suite in towers I went out in the common room while everyone was eating dinner. I took my laptop and played some of the mosquito ringtones found here. I could only hear the 17.4kHz and lower frequencies, while one of my suite-mates could hear up to 21 kHz. It was really fun to watch one guy try to figure out where the sound was coming from, while everyone else was calling him crazy, for they did not hear any sound. I suggest playing this prank on a person you know with good hearing, and punishing her for her good hearing.

Example 1=1 Channel; Example 2=6 Channels; Example 3=4 Channels; Example 4=8 Channels; Example 5=2 Channels

Example 1: The boy did a handstand.

Example 2: A tree fell on the house.

Example 3: The dog growled at the neighbors.

Example 4: Her husband brought some flowers.

Example 5: The silly boy is hiding.

http://www.jstor.org/view/00368423/ap070942/07a00070/0?currentResult=00368423%2bap070942%2b07a00070%2b0%2c03&searchUrl=http%3A%2F%2Fwww.jstor.org%2Fsearch%2FBasicResults%3Fhp%3D25%26si%3D1%26gw%3Djtx%26jtxsi%3D1%26jcpsi%3D1%26artsi%3D1%26Query%3Dcochlear%2Bimplants%26wc%3Don

http://www.utdallas.edu/~loizou/cimplants/

Hearing

The loss of hearing definitely affects the relationships between people more than sight. There are many factors that go into the psychological loss of hearing, and these factors can have a large impact on the person. According to an article by Robert Klotz, a hard of hearing person, “often is embarassed by his deficit and, in order to avoid detection, may answer a question which he has not completely understood.” In these cases, a person’s loss of hearing negatively impacts even simple interaction. For example, my 85 year old aunt will nod ‘yes’ to anything. You could ask her anything, and she’ll look at you as if she understands and nod. It definitely seems as if there’s an intangible barrier between us, and sometimes its near impossible to communicate. 

Furthermore, “the patient with a severe hearing loss may have been accustomed to receding into the background.” An example cited in the article which rings true to my aunt is the reluctancy to watch tv. She wouldn’t watch tv because in order for her to hear it, it would be way too loud for our comfort level. The lesson here is that its not just actual human-human verbal communication that is affected by hearing loss, for that can be compensated with the reading of “facial expression, lip reading, and general context of the conversation.” More than just the loss of hearing another’s voice, human relationships such as going to a movie, watching tv, and sports playing/watching are all negatively affected. The things I do which involve hearing are more than just conversation, all my hobbies and things I do which I love, all involve hearing. This loss would definitely cut me off from people, as nearly every relationship hinges on this hearing ability.

Feb 16, 2008

10:44 PM

http://www.jstor.org/view/0002936x/ap060758/06a00250/0?searchUrl=http%3a//www.jstor.org/search/BasicResults%3fhp%3d25%26si%3d1%26gw%3djtx%26jtxsi%3d1%26jcpsi%3d1%26artsi%3d1%26Query%3duses%2bfor%2bhearing%26wc%3don&frame=noframe¤tResult=0002936x%2bap060758%2b06a00250%2b0%2c07&userID=813b1ca9@vanderbilt.edu/01c0a848691ad32118258fbf11&dpi=3&config=jstor

No Smelling

So while we’re still dealing with senses around the nose and mouth, I’m going to continue my recap of the effects of the surgery. For a period of about a month my nose was blocked off, and I couldn’t smell anything. The thing I missed the most was definitely the smell of food. This got me thinking. What do I really smell? How often do I smell non-food? Granted, every now and then we’ll smell something bad in a room or a smell a new car smell, for example. Thats basically it.

So looking back on this I realized that I really only use my sense of smell when it comes to food. Even in the in-class experiment where my classmates smelled the smell on the q-tips, most of them were food (coffee, lime juice, etc). The other smell was acetone. But this just shows that almost all the smells we smell are dealing with food, which I think is pretty cool. This is really important and further illustrates how interwoven smells and tasting are.

 Feb 9, 2008

6:00 PM