Final Blog Entry

Sunday, August 27, 2008

I believe the most interesting thing I learned in Perception this semester is how much of our sensory experiences are subjective and created through the interaction of sensory neurons, pathways, and the sensory areas of the cortex.  I think I was most shocked by the fact that color vision is almost a completely subjective experience and truly a product of the inner workings of our mind.  Its amazing to think that the reason I green grass or a red apple is because that particular object is simply reflecting a specific wavelength of light and absorbing all others of the color spectrum.  From the wavelength information, it is also astounding to believe that it is possible that the photoreceptors in our eye can then only transmit information about light intensity yet because of the different types of photopigments they are able to indirectly communicate the wavelength information.  Had I not taken this class, it would have been hard for me to understand that perception is communicated from our sensory neurons to the cortex of our brain solely through action potentials.

The Aperture Problem

Sunday, April 20, 2008

The aperture problem occurs because each DS neuron responds solely to actions that are occurring within its own receptive field.  Therefore, a DS neuron oriented to respond to rightward movement, will respond to any extended contour moving in this direction and passing through its receptive field.  This means that the neuron will not take into account whether the object is moving to the right and slightly downward, to the right and slightly upwards or directly to the right.  It will respond vigorously in all three of these different situations making the neurons responses ambiguous. Despite this problem, the visual system is able to rectify the issue and allow motion to be accurately perceived by integrating this type of local information higher up in the path of the visual system.  This integration of local information to provide a bigger picture is a common practice throughout the nervous system. For example, the information received by the retinal ganglion cells is a more integrated version of the light information provided by the photoreceptors in the retina. As this information continues its movement through the visual system it is further integrated to provide an organism with a comprehensive understanding of its environment. The transformation of local information to a more global picture is essential to perception.

Synesthia

Sunday, April 13, 2008

Synesthia is a rare condition which causes individual’s senses to mix, meaning that the activation of one sense is aroused by another.  People with this condition can see specific colors when they hear noises or see letters change colors while reading. (Blake & Sekuler, 2006)  Other individuals may have sensations of touch when they taste specific things.  Studies have shown that the perception of color which those with synesthia experience may be do to the neuronal messages occurring in the brain.  Brain imaging techniques have shown that specific areas of the cortex associated with seeing color are activated when synesthetic individuals are experiencing these illusions of color (Blake & Sekuler, 2006).  This shows what a substantial amount of vision and color perception occurs in the visual areas of the brain.  I think it also demonstrates how the brain and neuronal activity controls so much of what we perceive in the world and essentially we must trust that the information our brain is processing and generating is an accurate image of the world in actuality.  Something I have commonly questioned is how I know what I am perceiving of the world is actually there and being portrayed to me accurately.  Perhaps, those people with synesthia have a more accurate and enlightened view of the world than those with “normal” systems of perception.  They certainly have a varied and unique manner and system through which they understand their environment.

 

Blake, R. & Sekuler, R. (2006). Perception. McGraw Hill: Boston.

The Cortex and Processing Visual Information

Thursday April 3, 2008

 I believe that there are so many different parts of the cortex devoted to the processing of visual information because there is such an extensive amount of information present in our environment which we are processing and assessing all of the time during the hours which we are awake.  Being able to recognize specific objects, and consume the visual information around us is essential to navigating and utilizing a person’s environment appropriately and effectively.  Because we take in such an extensive amount of varied information through the visual system, it only makes sense that a great deal of our cortex would be devoted to understanding and making use of this information.  In addition, there are minuet details of objects in our environment of which we must also be aware and have the ability to process visually because without such survival could be threatened.  Such a substantial amount of cortex is devoted to the fovea of the retina, because processing our environment in detail is so crucial.  In order, for people to effectively navigate and understand their surroundings, a great deal of cortex needs to be devoted to processing visual information.

Cortical Magnification

Sunday March 23, 2008

Cortical magnification allows the brain to most efficiently maintain those bodily mechanisms which require a significant amount of concentration and attention most often dealing with the finer details of perception.  According to Randolph Blake and Robert Sekuler in Perception, cortical magnification is defined as “the mapping of the retina onto the visual cortex so that the representation of the fovea is exaggerated or magnified” (2006).  A greater portion of the visual cortex must be devoted to the representation of the fovea because that area of the retina has neurons specialized for seeing fine details.  Perceiving the images with great detail requires that these neurons have more of the brain to use.  Similarly to the exaggerated cortical magnification of the fovea, the part of the cortex which deals with fine hand and finger movements is larger than that devoted to the elbow.  Because of cortical magnification, more of the visual cortex is devoted to seeing details and more neurons are being utilized for an incredibly important aspect of vision.

Blake, R. & Sekuler, R. (2006). Perception. New York: McGraw Hill

Roger Carpenter Quote

Sunday, March 16, 2008 

When Roger Carpenter stated “The eye is at once the master and the slave of vision,” I believe he was referring to the fact that the eye is the only means  through which we can see the world but does not have any choice in what it sees.  The vision the eye receives is determined by aspects of the surrounding environment making the eye a slave to vision.  It is also a slave because without the ability to see the eye is completely worthless to the organism.  The value of the eye is dependent upon its ability to provide a vision of the world.  The eye is simultaneously the master of vision because it is all an individual has to see the outside world.

Misperceptions Encountered When Living on a Boat

Sunday, March 9, 2008

For Spring Break this year, I went with forty of my closest friends at Vanderbilt to the British Virgin Islands (BVIs).  Our group of college seniors lived on two catamarans for seven days traveling around the BVIs and exploring the land and sea.  It was one of the most amazing experiences of my life. I learned a great deal about myself and my friends as well as the misperceptions that one can encounter when living on a boat for an extended period of time.  Specificially, I found that when I would go on to land after spending a great deal of time on the boat, I felt as though I was still rocking on the water eventhough I was on solid ground.  I thought that perhaps after several hours off the boat the rocking feeling would go away; however, I have been off the boat for two day now and the rocking sensation continues to come and go.  I think this may happen because when I was living on the boat my body and balance system had to adjust to life on the water.  Then, when back on land, my body remained apt for life on the sea and caused the rocking sensation.  Several days may be needed for my body to readjust to living on land.  However, this is only my own speculation and I must do further research to truly understand why the misperception occurs.

My Eyes and Optical Illusions

Friday, February 29, 2008

I feel as though my eyes and brain are incredibly typical in regards to optical illusions.  My eyes fall for the majority of optical illusions such as the picture of the three circles with a little slice taken out of them and arranged so that it creates the image of the triangle.  However, there is actually no triangle drawn in the picture, I just perceive it to be there.  My brain seems so convinced that the triangle exists that I most often must be clued into the fact that there is no triangle by another individual.  In addition, I can never see the optical illusions that are  pictures that if you stare at long enough a number of repeated objects such as sailboats becomes a completely different image. I am always the person who has to say they see it to keep people from nagging me.  I think the reason for the occurrence of both of these instances is because my eyes are use to seeing things in a certain way.  It is as if they have been trained to look for certain common things in my environment and not see those images that are out of the ordinary.  And it is this thought, that makes me wonder what I may be missing out on that is present in my environment.

The Price of Mistaken Words

Saturday February 23, 2008

 It is amusing and entertaining to other people when a person mishears a few words and as a results sings a song out loud that makes no sense or assigns an alternate meaning to a simple statement.  However, if you are the person who makes such a mistake it is incredibly frustrating, confusing, and a little embarrassing.  I feel as though I often make these mistakes for example until just a year ago I was convinced that the lyrics of the song by Tracy Chapman, “Give Me One Reason,” were: “Give me one reason of steal, and I’ll turn right back around.” It took  bet with one of my friends about the lyrics to set me right in my ways and accept that the words are actually: “Give me one reason to stay here.”  This mistake cost me around twenty dollars, and I found it quite frustrating.

However, this example does not do justice to the time I misheard two friends talking about going to get a manicure and pedicure.  One of my friends told the other “I cannot wait until our mani and our pedi.” I was listening to them talk using about half of my attention span and thought I heard that they could not wait to go to Armenia and Arpedia.  From that statement, I interpreted that they were leaving the U.S. to travel to two faraway lands, one that I had not even heard of called Arpedia.  I was distraught and devastated but did not want to comment on my feelings for fear of making them feel bad for going.  Finally, I gained the courage to ask them what they were taking on their trip to Armenia and Arpedia, and they looked confused and asked what I was talking about.  I then explained and the situation was rectified.  However, I do not believe I nor my friends will ever forget that day.  They still laugh at me about it occasionally.

“Deafness cuts me off from people” -Helen Keller

February 14, 2007

I believe Helen Keller’s quote, “Blindness cuts me off from things; deafness cuts me off from people,” captures the true importance of the human sense of hearing.  The ability to listen to others’ words whether it be spoken or put to music creates an understanding between people.  The tone, inflections, and emphasis in an individual’s words and statements allows them to communicate themselves efficiently to another person. Whether someone is expressing an emotion, giving a lecture, or telling a joke, not being able to hear them would impair your ability to truly comprehend the truth and meaning of the statement and the speaker.  Without hearing the different aspects of a person’s voice, it would be incredibly difficult to assign the appropriate meaning in a individual’s words and expressions.  I understand that not being able to see would keep one from knowing the structure and composition of things, but I believe that sacrificing the connection made through hearing and understanding others thoughts and feelings would be significantly more disappointing.