Stress and Continuation of Senses
Part 1: Taste
Because the characteristics of taste receptor cells are genetically determined, people vary in their ability to taste some molecules. Taste papers are small strips of paper impregnated with chemicals that test for the perception of discrete tastes. Phenylthiourea papers, for example, taste bitter to seven out of ten people, and sodium benzoate papers taste sweet, salty, bitter, or tasteless to different people.
Materials:
· video: Are You A Supertaster – Test Your Tongue (02:23)
· blue food coloring
· cotton swab (Q-tip)
· small piece of paper with a hole punch out (can be a piece of notebook paper that you have cut)
· Camera
Procedure:
1. Watch the video and follow the instructions to count the number of papillae on your tongue.
2. Take a picture of your experiment set-up. Make sure the picture includes a piece of paper with your name and UAG student number.
3. Record the number of papillae in the table below.
4. Based on your results, determine if you are a supertaster, average taster, or non-taster.
Number of Papillae
Supertaster, Average Taster, or Non-Taster?
Insert the picture you took of experiment set-up. Make sure the picture includes a piece of paper with your name and student number.
Answer the following questions:
1. Were you surprised about the results of your tasting level? Why or why not?
2. Explain the neurological path associated with tasting.
3. What element is responsible for sour tasting?
4. Does an artificial sweetener have the same response as a natural sweetener? Why or why not?
5. What areas of the tongue are responsible for the different tastes?
6. What physical or health related factors could limit one’s ability to taste?
Part 2: Vision
In this section of the lab, you will test visual acuity, astigmatism, blind spot, color vision, depth perception, peripheral vision, afterimages, and optical illusions.
Materials:
· Snellen eye chart (online) Vision Source Signature Eye Care .
· index card
· astigmatism test chart (online) NVision Centers
· blind spot diagram
· metric ruler
· Color-vision test (online) Color-blindness.com
Activity 1: Visual Acuity
The amount of detail the eye can distinguish is known as visual acuity. The Snellen eye examination chart uses lines of progressively smaller letters to measure how well the subject’s eyes distinguish details, at a distance of 20 feet, compared to the human norm. Visual acuity measurements are stated as a series of two numbers. The first number is the distance from the subject to the chart in feet. The second number is the distance in feet that a normal eye can see as clearly as the subject can at that distance. Normal human vision is 20/20.
1. Follow the directions from this website: Vision Source Signature Eye Care .
2. The subject covers the left eye with an index card.
3. The observer points to each line of the chart and waits from the subject to call out the printed letters.
4. Continue until the subject can no longer read the letters correctly or until all of the lines are read.
a. Visual Acuity right eye:
5. The subject moves the index card to cover the right eye and repeats the test.
a. Visual Acuity left eye:
Activity 2: Astigmatism
Astigmatism is a condition in which the cornea or the lens is irregularly shaped. The light rays do not focus at a specific point on the retina. This results in blurred or distorted images. The test for astigmatism uses a picture that resembles a spoked wheel. A person with astigmatism will see thick, dark lines in certain areas when the chart is viewed from a distance.
1. If glasses are usually worn, the subject should remove them for this test. Contact lenses do not have to be removed.
2. Follow the directions from this website: NVision Centers
3. The subject covers one eye with an index card. The subject then views the astigmatism test chart and states whether or not any thick, dark lines are observed on the chart.
Is astigmatism present in your right eye?
4. The subject then moves the index card to cover the right eye and repeats the test.
Is astigmatism present in your left eye?
If yes, were you aware of the astigmatism before today?
If yes, do you wear glasses to correct the astigmatism?
If astigmatism is present, describe what you saw on the astigmatism chart.
Activity 3: Blind Spot
The blind spot is the area on the retina that contains no photoreceptors.
1. The subject holds the blind spot diagram at arm’s length, with the dot to the outside and the + in front of the right eye.
2. The subject closes the left eye and, staring directly at the +, slowly moves the diagram closer until the dot seems to disappear.
3. The observer measures the distance from the subject’s face to the diagram at the point where the dot disappears.
At what distance did the dot disappear during the blind spot for the right eye? [enter number] cm
4. The subject closes the right eye and repeats the test to find the blind spot on the left eye. This time, hold the diagram with the dot to the outside and the + directly in front of the left eye.
At what distance did the dot disappear during the blind spot for the left eye? [enter number] cm
plus sign and black dot
5. List several circumstances in which it would be important to be aware of your blind spots.
Activity 4: Color Vision
The retina of the eye possesses two types of specialized nerve cells known as photoreceptors. They are called rods and cones because of their distinctive shapes. Rods function in dim light and perceive shades of gray, like what you see when your eyes adjust to the darkness. Cones function in bright light and provide sharp, colorful daylight images. There are three different types of cones – red cones, green cones, and blue cones – and each type is sensitive to a different range of wavelengths of light. If any of the three types of cones do not function properly, color perception deficiency occurs. The most common type is red-green color perception deficiency, which occurs when red cones are missing or do not function. A person with this color perception deficiency cannot distinguish between red light and green light.
1. To your knowledge, are your color perception deficient? Is anyone in your family color perception deficient? If yes, whom?
2. Go to the following website. You will arrange some colored squares in order of their color similarities. Color-blindness.com
3. Take a screenshot of the D-15 Disc Arrangement CVD Test results including the date and time.
4. Summarize what you learned about color blindness in 3-4 sentences.
5. Some cities hang their traffic lights from left to right rather than top to bottom. Explain why this might cause problems for a driver with red-green color perception deficiency.
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