Sensations and Perceptions of RDT

Hello everyone!

I hope that fall is treating everyone well as we get ready to welcome in October! This next post is corresponding with an assignment for my psychology course designed to have me to reflect on personal experiences which exemplify various ways in which humans sense and perceive the world around them. The topics about which each paragraph is written can be see italicized above each entry. Enjoy reading a little about me!

Sensation vs Perception

Recently I was studying with two friends when one of them began to play a song on their phone which I had heard multiple times before. However, my friend asked me if I knew the significance of the song and understood its meaning. I confessed that I had never really listened to the words. Therefore, I later listened to the song this time paying close attention to the words and soaking in its meaning on a deeper level. After doing so, my appreciation for the significance of the song, understanding of why it had grown so popular, and my ability to critically analyze the meaning behind it dramatically increased. Prior to this, I had only ever sensed the song in that my ears heard its melody, instrumentation, beat, and words. But I had not perceived the song in that I had never devoted the mental energy to deciphering what those sensory inputs meant. In this example, sensation without perception was a significantly more superficial experience.

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Top-Down Processing

When I was four years old I was attacked by an unleashed dog, and this experience caused me to develop a fear of dogs that lasted for years. In fact, my fear grew to the point that I became afraid of nearly all large animals both domesticated and wild. When I would see a dog, deer, horse or even goose, I would run to my mother not wanting to get close to it. This continued till I was nearly nine years old. I believe that this fear was partly motivated by top-down processing. In this form of mental processing, one constructs his or her perceptions from past experiences and expectations. My past experience with the violent dog was very negative; therefore, that experience shaped an expectation that all dogs will attack me. This mindset motivated my fear. Fortunately, age and the arrival of my own family’s dog cured me of my growing phobia.

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Signal Detection Theory

My family has an older dog who suffers from a number of health struggles. During the night, he often will need to be let out to relieve himself as we have woken up too many times to unwanted surprises on our living room or kitchen floors. Whenever he needs to go outside, he will begin to pace up and down the hallway producing a soft and subtle clicking noise with his toenails. To many, that clicking noise may be imperceptibly quiet. But for members of my family, we are attuned to it so that once he starts pacing,  we will hear it, wake if necessary, and take him out. This is an example of signal detection theory in that I and my other family members are able to detect the very weak stimulus of his pacing paws, and this can likely be largely attributed to the fact that we have an expectation that he will pace at that time of day, we have negative experiences with him not being taken out in time, and our brain has a developed a particular alertness to that sound.

Parallel Processing

My brain performs parallel processing all the time, just as nearly everyone else’s brain does as well. An example of this occurred a few days ago in which I was walking out of the parking lot about to cross the street at which time a car drove me rather quickly. For a split second I had the chance to look inside the car and see a profile view of the driver as well as the color of his sweater. I did not see his face though. Amazingly, I was immediately able to identify who it was based on his profile and sweater. Parallel processing played a role in the example because there would have been no way for me to have made all of the same observations – car make and model, color of sweater, profile view of driver – sequentially. Therefore, they must have occurred simultaneously as in parallel processing.

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Opponent-Process Theory

This idea, developed by Hering, states that retinal neurons which “see” red color travel down the same series of axons that “see” green color; however, only one color (red or green) can be seen at once thus preventing the human eye from seeing reddish-green. The same can be applied to yellow-blue, and white-black. While this is a difficult concept to apply personally, I can relate it to the image of the American flag I have included below. After staring at the flag for 30 seconds and then looking away onto a white sheet of paper, the stars portion of the flag in the upper left hand corner, which is yellow in the figure, appears blue on the paper. This transformation occurs because the neurons that perceive yellow are fatigued by our eyes’ staring at the flag for 30 seconds. When one looks at a white sheet of paper, only the neurons that can see blue are able to transmit information, and since white contains all colors, the inability of the yellow neurons to see yellow allows for the yellow-blue axons to only see blue.

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Figure-Ground relationship

While studying with a group of students last week, I had an experience in which my figure-ground relationship changed. At one point in the conversation, a girl began sharing a story to our study group and became the focal point of my attention. During her story, however, a professor in the room adjacent to mine began engaging in a conversation with another professor about a class I was interested in. At this point my attention shifted to the professor and what he was saying. In this example my original figure was the girl and her story, and everything around her including all the other people in our presence were part of the ground. However, when I listened to the professor, he became the figure and everything else, including the girl became the ground.

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Shape Constancy

My largest hobby is photography, and as a photographer I have learned how the shapes of objects can be manipulated depending upon how the photographer may shoot those objects. For instance, the two following photos are taken of the exact same scene within the basement of my college’s library; one was taken with a wide angle lens and the other was taken with a mid-range telephoto lens. The perspective between the two photos is very different; one has a  wide, pulled-apart, spacious feel in which the shelves appear spread apart from each other. The other has a compressed feel in which the shelves are appear bunched up together. Interestingly, however, when viewing these photos, our minds are able to perceive the correct shape of the shelves even though the shelves appear slightly different in these images. This is an example of shape constancy in mental perception.

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Binocular Cues

This summer I had an internship at the College of Medicine at the University of Kentucky in Lexington, and one night I was at a gathering of friends at the home of the pastor of the Lexington church I attended. That evening I was playing a game when one of my contact lenses became dislodged from its proper position on my cornea and became wedged in the upper right corner of my eye. Since I wear gas permeable hard contact lenses as opposed to flexible soft ones, I could not easily remove it. I desperately attempted to remove it on my own in the bathroom, but it would not budge and my eye became increasingly irritated. Therefore, I had to drive back to the campus with one eye effectively shut and one eye open. As well, I had to enter my dorm and room and get my contact tools all with one eye incapacitated. I recall that my vision that night was significantly different while riding in a car with only one eye open. This can almost certainly be attributed to the fact that I did not have any binocular cues during that period since I was viewing the world through only one functioning eye.

 

Image References

1 http://www.futurity.org/teen-brains-predict-hit-songs/

2 http://www.mayfirm.com/blog/attacked-dog-santa-maria-ca/

3 http://hackingphotography.com/motion-blur/

4 http://gettingstronger.org/2010/05/opponent-process-theory/

5 http://michaelwillyamz.com/2011/10/03/the-disciplined-prophet-running-back-to-the-lord-jonah-part-2-of-5-post-93/

6 and 7 Personal Images, RDT Photography

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