Over the course of the semester, I have become more and more impressed with the complexity of the human sensory systems. Probably the most interesting sense to learn about has been gustation, or taste. I thought it was interesting that taste is so unique, in that it sends its neural message over two cranial nerves (instead of just one, like vision, hearing, and smell). I also thought it was interesting to learn that when we perceive a sensation of spiciness in food, it is actually due to the tongue’s receptors detection of capsaicin, which signals pain. So, it seems that when my best friend Rachel pours tabasco sauce on everything imaginable (including waffles), she is actually just putting herself in a painful situation! Another aspect of taste that I had never really thought about before, is the fact that satiety is food-specific. This explains why, after eating a giant basket of greasy French fries at Noshville, I have no trouble immediately downing a chocolate milkshake. 

Last summer, I tried to take up cooking as a hobby. I realized that it’s perfectly easy to follow instructions of a recipe, but without a recipe, it’s  very difficult to successfully play with the specific flavors in every food. Cooking with this kind of intention requires knowledge of taste suppression, where one taste is toned-down by another one. 

 

In conclusion of this blog, I would like to say that this class has given me a huge appreciation for the systems that govern human perception. Many weeks, I came back from class to tell my roommate about topics we discussed, and how astonishing the complexity of perception is. I have really enjoyed this class, and hope I can learn more about perception in my future classes. Thank you, Professor Boucher!

We already talked in class about how pre-Renaissance painters used occlusion to indicate depth. The effect of this is that it makes painting seem much “flatter” or two-dimensional than later paintings. One thing we did not talk about in class, though, is that pre-Renaissance also, to paint objects as being in the distance, artists would use lighter, duller colors, while using darker, more intense colors for objects close-by. 

The aperture problem refers to the “inability of a motion sensor with a restricted field of view to register unambiguously the direction of motion of an extended contour moving through the sensor’s field of view.” This is because every Direction-Selective neuron can only respond to actions that occur within its own receptive field. If an object moves through a neuron’s receptive field at the right speed and direction (for this example, let’s say it prefers objects moving towards the left), it will give a strong response. However, the neuron cannot send information that explicitly indicates whether the object was moving to the left and upward, or to the left and downward — all movements to the left at that specific velocity will send the message that it is simply moving to the left.

When Professor Boucher told us about synesthesia, it was a real eye-opener for me (so much so that I even added “synesthesia” as one of my official “Interests” on my Facebook page). It really helped me understand how incredibly unique each of our experiences are. Synesthetes obviously have a very distinctly differently way of seeing things, but I think that my experiences are probably just as different from my roommate’s as mine are from synesthetes. We all inhabit our own worlds that are unavoidably different from others’. This is something that I think everyone senses and guesses on some level, when we realize that no one EXACTLY knows what it’s like to be in our shoes. This can feel isolating at times, and I imagine that synesthetes may sometimes feel cut-off from the rest of the world because of their unique experiences. It seems to me that one main reason why humans have such a need for community — if we all have such different experiences, it seems like each of us has a piece of the puzzle that only a good deal of collaboration can make sense of.

 

Hearing about synesthetes made me think about the fine line between something like synesthesia (which is sort of romanticized, an idea that everything in life produces a specific colorful identity) and mental disorders that doctors insist must be medicated. In medicating certain disorders, is it possible that we’re unjustified in suppressing someone’s reality on the basis that it doesn’t resemble what the rest of us claim are “normal”? Who is to say what’s “correct” perception, anyways?

 

It’s amazing to me to find out that objects are not themselves made up of colors–that actually, color is just a supplementary aspect of an object that my brain attributes to it. The complexity and intricacies of all of the systems that make perception possible are astounding. Every section in this class gives me a feeling like being a homeless person living out of a BMW car: I have done nothing to deserve or have earned this brilliantly constructed body — heck, until this year, I knew very little about the way a lot of my body even worked. 

The Universe of the Eye

Universe of an Eye

The nature versus nurture debate seems to crop up in just about every discussion of human development, and the development of the visual system is no exception. There is convincing evidence on both sides for us to conclude that both nature and nurture influence the development of the visual system, and so we see that “nature” and “nurture” are not mutually exclusive. One piece of evidence that nature controls the development of the visual system is the findings that infants have a preference for lines of certain orientation (horizontal or vertical, rather than diagonal). However, nature’s role in development has been noted in experiments that involve kittens being placed in environments that only have lines of certain orientation (e.g. vertical lines only). When the kitten is taken out of such an environment, we see that it responds differently in the visual cortex to vertical lines than it does to lines of other orientation. 

 

Thus, it seems that an adequate equation for the relationship between nature, nurture, and development might look something like this: 

     Development = Nature + Nurture + (Nature x Nurture)

 

There could be several consequences of having an underdeveloped visual system. An infant with abnormal vision will not be able to interact with the world in quite the way that a “normal” child can. Much of our development in childhood depends upon our visual system and the actions that the system enables (e.g. learning how to judge depth and grasp a toy at arm’s length in one attempt). Thus, our visual system in our early years affects our development of other skills, like motor coordination. 

Even beyond developmental effects of having an impaired visual system, there are often social consequences as well. Especially during childhood, much of how children define themselves is through abilities like athletic skill. Those children who cannot participate in sports or join other children on the monkey bars could become at risk of being excluded because of their handicap. Thus, an abnormal visual system could also result indirectly in slower social development.

Cortical Magnification refers to the number of neurons that are present in the visual cortex, neurons being responsible for processing stimuli information. While there are significant benefits to this process, there are also disadvantages that come with it. And yes, some of them are not only bad — they are ugly.   THE GOOD: The small region that is the center of the visual field (the fovea) is represented by a large number of neurons, which means that our visual acuity is greatest at the center of our visual field, at a focal point. In other words, the thing that we are most focused on gets the best representation. This is a good thing; it would be rather inefficient and impractical if we got more visual information about the things that we weren’t really interested in. THE BAD: Our peripheral vision acuity is not that great. We aren’t usually aware of how inadequate our peripheral vision is, because we instinctively make head movements to compensate for its inadequacy. It makes sense, though: since there are fewer neurons in this area, each neuron is responsible for a relatively large part of the visual field, which necessitates an increase in the size of the neurons’ receptive fields. THE UGLY: As if all the things I mentioned under “THE BAD” weren’t enough, there are some ugly ways that cortical magnification hinders us in life. For example, when you are trying to look like you are paying attention in class, but really want to look at your neighbor’s computer to see the latest celebrity gossip, it’s pretty impossible unless you actually make an obvious head-turn. Consequently, countless hours per year have to be spent actually paying attention in class, when we could have been getting the most recent updates on Britney Spears’s tragic meltdown and. 

“The eye is at once the master and slave of vision.” – Roger CarpenterObviously, the organ that facilitates vision is the eye, so in that sense, the eye is master of vision. But truly, visual perception operates on its own rules; sometimes our perception of objects or events in our visual field is deceptive (as is evident in the myriad of optical illusions we have seen, like the Necker cube, Magic Eye art, etc).This quotation really brings to mind what has been a theme for me lately — understanding the different ways that people perceive, and how we are all unavoidably limited in our perception of reality. This semester has been an experience of learning to be more accepting of others’ opinions, perceptions, and reactions to ideas and events. Before I learned so much about the ways that our brains construct a unique perception of reality, I felt more frustration towards others when we didn’t see eye-to-eye. Now I recognize that my “reality” may be different from others’ “realities” but that neither one is more “right” than the other. In the past, I was more likely to feel that other people can be willfully ignorant, but now I acknowledge that we all experience life in a unique way.

The best use of optical illusions is seen in animation. Animation is something that we tend to take for granted in perceiving a series of pictures that run rapidly, one after another. Even though the pictures are in reality stagnant, the rapid succession produces the illusion of movement. This optical illusion has greatly contributed to my enjoyment of Saturday mornings throughout my life, as well as many nights laughing at the antics of the characters on the show “Family Guy.”   The Necker Cube is an optical illusion that shows a cube made with lines of ambiguity. The lines seem ambiguous when two lines cross, and the drawing does not necessarily show which line is in front or behind of another. In this way, the viewer’s perception of the cube is that is flip-flops forward and backward. This is called a multistable perception.  It is made possible when the human visual system is forced to pick an interpretation of each ambiguous line that makes the cube consistent as a whole. In my research on the Necker cube, I found that it is often used in testing artificial intelligence systems, to determine whether the system can achieve a consistent interpretation as humans do.  

Mondegreens are one of the most entertaining mistakes someone can make. With a couple of parents who aren’t getting any younger, it seems that mondegreens in my household become more common and more outrageous every year. There are several instances of misinterpreting lyrics or sayings in my family.

* When the song “Two Tickets to Paradise” comes on, my parents like to sing, “Two chickens to paradise!”

* My uncle thought that the phrase “It finally dawned in me…” was “It finally donged on me”

 * In Queen’s song “Bohemian Rhapsody,” there is a line that says, “Bismillah no, will not let me go,” which my mom            misheard as, “Ms. Miller no, will not let me go” 

 * Several years ago, there was a popular R&B song called “Where My Girls At?” My mom thought they were saying,            ”Where my pearls at?” which doesn’t make much sense with the rest of the song about getting a gang together to                  fight a rival girl. 

We talked in class about how there are many different uses for hearing. Localization of objects and sound sources, recognition of sound sources, communication,  motor coordination, and enjoyment of music are all important components of our conscious experience that hearing is involved in. All of these things are important; all (except the enjoyment of music) are essential to our efficiency in movement and communication. However, if one suffers hearing loss, the other senses can compensate for these abilities. (Even if you can’t hear, you can still maintain a level of motor coordination; even if someone can’t communicate through speaking to you, they can still write their message, or you can read their lips.)

 The only one of these benefits of hearing that cannot be compensated for is the enjoyment of music. Someone who is completely deaf cannot use any other sense to hear music. Because of this, and the importance of music in inspiring, encouraging, and comforting us, listening to music is the most valued and irreplaceable use for hearing.

 In spite of my appreciation  for music, I feel that being deaf would not be as debilitating as being blind. Helen Keller said, “Blindness cuts me off from things; deafness cuts me off from people.” This seems to imply that deafness is more debilitating than blindness. However, I would argue that being cut off from “things” is more dangerous than being cut off from people. Most of the dangers that one encounters in daily life come from “things,” and not people. Dangers come from cars speeding around corners as you’re beginning to cross the street, from holes in the ground that you can trip into and hurt yourself. Granted, there are dangerous people in the world — but you’re generally more likely to be harmed by slipping on some ice that you couldn’t see, than by a mugger.

 The acoustic reflex’s job in dampening one’s own voice is important because of our ears’ close proximity to our mouth. Dampening our voice probably gives a more gentle experience of listening to our ears, and protects our ears from damage. 

(2/16/08, 06:19PM) 

Smell is definitely an influence on my buying behavior. The best example I can think of this regards the Exxon gas station next to the Green Hills Mall. Most of the time when I am filling up my car with gas, I meander inside the gas station to drink a Coke, perhaps buy a couple of granola bars to snack on while I wait for my car to fill. This Exxon in Green Hills is the one exception to my habit. Tt smells so consistently horrendous in their store that I rarely go inside. If I do go inside, it is for some bare necessity, and I retreat out of the chemical-smelling stench as soon as possible. If that Exxon was not home to such a putrid smell, I would definitely be spending more time, and thus money, in the store.

My favorite smell is probably that delightful one that oozes out of every corner of a greasy cheese pizza. There are few things that can make me salivate like fresh pizza. Over the years of my life, pizza has been connotated with a plethora of good experiences. At any classroom celebration or birthday party, you can bet that Papa John was there.

Smell is often described as the “Fallen angel” of the senses, because we abandon our appreciation for it the second it ceases to please us. It is a good thing that the rotting corpse of a rat smells so horrible, or else we would never know that such a health risk was lying under the refrigerator. However, when a bad smell is in our vicinity, we try to plug our noses and block it out.