Sensation and Perception

1. Sensation and Perception Complete each of the following activities. Answer any questions in the activity and label those questions according to the activity. There are 6 activities- A thru F.

2. Activity ABlind Spot in Vision Instructions: Hold the paper with the X and Y at arm�s length with your right hand. With your left hand, cover your left eye. Focus on the X and slowly move the paper toward your eye. What happens to the Y as you move the paper? Hold the paper with the X, Y and Z at arm�s length with your right hand. Cover your left eye with your other hand. Focus on the Y and slowly move the paper toward your eye. When the Z disappears, hold the paper at that point. Shift your focus to the X. What happens to the Y and the Z?

3. Activity ABlind Spot in Vision How this happens: The area at the back of the eye where nerve fibers from all parts of the retina collect to form the optic nerve is called the optic disc, or the blind spot. This portion of the retina is functionally blind. You have a blind spot in each eye, which means you have two spots in your field of vision. These holes are eliminated by eye movements that shift the parts of the visual field to different portions of the retina. In addition, our visual system tends to fill in gaps in what we see, in a manner similar to the Gestalt principle of closure. As a result, we are unaware of our blind spots and require demonstration such as what you just did to illustrate their existence. Question: 1. What happened to the Y as you focused on the Z? What happened to the Z as you focused on the Y? 2. Based on the above explanation, explain what happened to the Y in the first example and to the Y and Z in the second. Use the correct terms from the explanation.

4. Activity BDepth Perception Instructions: Work in pairs; one student is A and the other is B. Person A: Hold the straw parallel to the ground about two feet in front of B�s face. Person B: Place the toothpick in the straw. Person A: Remove the toothpick and give it back to B. Reposition the straw parallel to the ground and about two feet in front of B�s face.Person B: Cover your left eye and place the toothpick in the straw. Repeat the same process with your right eye covered. Reverse roles and allow the other person to attempt the procedure.

5. Activity BDepth Perception Questions: People use monocular and binocular vision to perceive distance and depth. Look up these two terms in your textbook. Define and give examples of each. How does this experiment test depth perception? How is depth perception perceived differently using one eye as opposed to both eyes?

6. Activity CSensation: Movement Detectors in the Visual Cortex Instructions: Go to the following website: http://www.funlinks.com/spinning-spiral.html Stare at the rotating disc for one minute. Fix your gaze on the disc and try not to let your eyes move. After a minute has passed, shift your gaze to your classmate�s head or your hand. What happens? 2. Try the process with one eye covered. What happens? What does this tell us about the effect of the spiral on the eye itself?

7. Activity CSensation: Movement Detectors in the Visual Cortex Explanation: The visual cortex contains specialized feature and movement detector cells that respond only to a particular type of visual input. When the disc spirals in, you are over stimulating and fatiguing the cells that are programmed to respond to this type of inward movement. When you shift your gaze and the inward movement detectors stop firing, there is a tendency for the corresponding outward movement detectors to start firing for a few seconds.

8. Activity DBalance Sensitivity Stand on one foot without support for 20 seconds. 1. What sensations did you feel in the foot and leg on which you were standing? 2. How are these sensations related to balance? Stand on one foot again without support for 20 seconds, but this time close your eyes. 3. Compare the sensations you felt this time with the way you felt when your eyes were open. 4. What does this mean? What senses are important for balance? 5. What did you do when you felt off balance? Why? With your eyes open, spin yourself around quickly five times and then with your eyes shut, stand on one foot again. 6. Compare the sensations you felt this time to the two previous trials. 7. What did you do when you felt off balance? Why? 8. What do you think caused these differences?

9. Activity ETaste Buds Internet Quest Use the Internet to find the answers to the following questions. What are the four tastes? Draw a tongue and label the areas for each of these tastes. Why do some people disagree with this map of the tongue? How does smoking affect taste buds? Why does toothpaste change the taste of foods? The Japanese claim a fifth taste. What is it called? What does it taste like? What foods have this flavor? Although taste and flavor affect our food preferences, what other factors come into play? Give an example. What is the inability to taste called? Why is this rare? What is more often the cause of a lack of taste?

10. Activity FSkin Sensitivity Research using the Internet to find the following information. How is your sense of touch different from all other senses? In what way is the sense of touch the most aware of the senses? What three body parts are the least sensitive to touch? Why are certain body parts more sensitive than others? Why do people who are blind use their fingertips to read Braille? To what feeling are most of your nerve endings devoted? Why? What is haptic technology? Give an example. Look up the Aristotle Illusion. Try it. How does it work?