Senses Lab
Name:________________________
Class:________________
In this lab, you will examine an eye model and use tests to detect sensory disorders. At the end of the lab, you will write
2 mini-essays describing the some of the tests and their conclusions. You will be graded upon your answers to this
worksheet, your teamwork and lab skills, and your written paragraphs.
Pre-lab Questions
1. Use the diagrams below to show how light enters the eye and where it comes to a focus point in each of the
following conditions. Normal eyesight has been done for you as an example.
2. Differentiate between conductive hearing loss and sensorineural hearing loss. What are the causes and
treatment of each?
3. What sensory receptors does our body use to determine balance, and where are each located?
Functional Eye Model
Set up the functional eye model as shown in the picture below. You should not put a corrective lens in front of the eye
model. The clear plastic stand that says “EYE model” is the visual stimulus. You should put a bright light in front of the
stimulus (a cell phone flashlight will work). Adjust the placement of the stimulus until you can see a clear picture of the
stimulus on the back of the eye.
1. On the diagram above, label the parts that represent the cornea and the retina.
2. What part of the eye model represents the lens? ________________________________________________
3. Draw how the stimulus appears on the retina, when the model is set up as shown above.
3. Once the stimulus is clearly focused on the retina, move the stimulus closer to the eye model. The image on the
retina should now be blurry. Demonstrate the process of accommodation by adding more saline to the lens until the
image on the retina comes back into focus.
a. What is accommodation?
b. How did you change the shape of the lens?
c. What makes the lens in our eyes change shape?
d. Making the lens flat allows us to see (circle one) distant / nearby objects clearly, while making the lens round
allows us to see (circle one) distant / nearby objects clearly.
4. Position the stimulus so that it is focused on the retina. Now, adjust the top of the eye to elongate the eye. Use
corrective lenses to restore image clarity. Then, answer the questions below.
a. When you lengthen the eye, which eye disorder are you modeling?
b. What are the two major causes of this eye disorder in people?
c. What type (shape) of corrective lens corrects this disorder?
5. Position the stimulus so that it is focused on the retina. Now, adjust the top of the eye to shorten the eye. Use
corrective lenses to restore image clarity. Then, answer the questions below.
a. When you shorten the eye, which eye disorder are you modeling?
b. What are the two major causes of this eye disorder in people?
c. What type (shape) of corrective lens corrects this disorder?
6. This model does not allow you to demonstrate astigmatism. How could you change the design of the model to show
astigmatism?
Vision Tests
1. Test yourself for astigmatism. Stand 8-10 feet away from the chart (the space should be marked for you). Cover one
eye with your hand and look at the image. Repeat for the other eye. If you have corrective lenses, try to do the test first
without your lenses, and then again with your lenses.
If some lines appear darker than others, you are likely to have an astigmatism. Why does this test check for
astigmatism?
2. Test your visual acuity using the Snellen eye chart. Stand 20 feet away from the chart (the space should be marked
for you), cover one eye, and read the letters – your partner will check your accuracy. Repeat for the other eye. Record
the number of the line with the smallest-sized letters read.
If you wear glasses or
contacts, do the vision test
Record your numbers here. Left eye__________ Right eye ___________
both with and without your
corrective lenses!
If it is 20/20, the person’s vision for that eye is normal. Any value less than one indicates myopia (e.g. 20/40 indicates a
person reads objects clearly at 20 feet that a person with normal vision can read at 40 feet). A value greater than one
indicates unusually good far-vision; a person with a score greater than one may, however, not be able to focus on close
objects.
Explain what your numbers mean.
3. Demonstrate your blind spot.
Hold the picture above about 18 inches from your eyes. Close your left eye and focus your right eye on the dot. Move
the figure slowly toward your face, keeping your eye focused on the dot. Eventually, the plus will disappear.
At approximately what distance does this occur? ___________________________
Repeat the test for the left eye. This time, close the right eye and focus the left eye on the plus. Record the distance at
which the dot disappears. _________________________
Explain why we have a blind spot.
Explain why this test doesn’t work if both eyes are open.
4. Test yourself for color blindness.
Look at each picture in the Ishihara’s tests for color deficiency. You may look at a book or your teacher may be show the
images on PowerPoint. Record what you see in the table below. Possible answers include numbers, nothing (no
distinct image), one traceable line, or two traceable lines. Then, check your answers against the key. If you see the
‘correct’ picture, put a check in the normal column. If what you see indicates color deficiency, write down the type of
color deficiency shown.
Image Number
1
2
3
4
5
6
7
What you see
Normal or abnormal vision
8
9
10
11
12
13
14
Viewing the ear canal and tympanic membrane
1. Obtain an otoscope and fit the largest diameter speculum that will comfortably fit in your partner’s ear.
2. Turn the otoscope on by screwing the handle in.
3. Hold the otoscope between your thumb and first finger (like a pencil) and lightly rest the little finger of your
otoscope-holding hand against your partner’s head to brace it.
4. Grasp your partner’s pinna and pull it up, back, and slightly laterally.
5. Carefully insert the speculum of the otoscope into the external auditory canal just far enough to permit
examination of the tympanic membrane. Note its shape and color. The healthy tympanic membrane is pearly
white. Also notice if any redness or earwax is present in the auditory canal.
6. When finished, wipe the speculum with an alcohol swab and turn off the otoscope by unscrewing it.
Describe what you saw below.
What disorders can be detected by viewing the ear canal and tympanic membrane?
Weber test for conductive and sensorineural deafness
1.
Strike a tuning fork with a rubber mallet to make it vibrate. Place the tuning fork directly on top of your
partner’s head, in the middle.
2. Ask your partner whether they hear the sound equally loudly in each ear. If the sound is heard equally
loudly in each ear, then your partner has equal hearing and / or hearing loss in each ear. If
sensorineural deafness is present, the sound will not be heard in the deaf ear. If conductive hearing
loss is present, then the sound will be louder in the ear that has conductive hearing loss.
List your results here and describe what they mean.
Rinne test for conductive hearing loss
1. Strike a tuning fork with a rubber mallet and place it on your partner’s mastoid process.
2. When your partner indicates that he or she can no longer hear the sound, hold the still-vibrating prongs close to
his/her auditory canal. If your partner hears the sound again, then he or she does not have conductive hearing
loss. (AIR CONDUCTION TEST)
3. Repeat the test, but this time hold the prongs close to the ear first. When your partner indicates that he or she
can no longer hear the sound, hold the handle of still-vibrating fork against your partner’s mastoid process. If
the subject hears the sound again, then he or she has conductive hearing loss. (BONE CONDUCTION TEST)
Record your results in the table below. Put a + for each test that demonstrates normal hearing, and put a – for each test
that demonstrates conductive hearing loss.
Can you continue to hear the sound after the tuning for has been moved?
Left ear
Right ear
Placed by auditory canal
first (air conduction test)
Placed on mastoid process
first (bone conduction test)
Do your results indicate conductive hearing loss? Explain.
What are some common causes of conductive hearing loss?
Romberg test for equilibrium
The Romberg test determines the soundness of the spinal cord and proprioceptors. A person with neuromuscular
disorders may have difficulties with balance that are apparent only when their eyes cannot be used to compensate.
1. Have your partner stand with his or her back to the whiteboard (but not touching)
2. Draw one line parallel to each side of your partner’s body. He/She should stand upright, with feet together,
eyes open and staring straight ahead for 2 minutes. You should look for swaying motions.
3. Repeat the test, but this time with your partner’s eyes closed.
4. Repeat the test again, first with eyes opened then with eyes closed, but this time have your partner stand with
his / her shoulder to the whiteboard so that you can pay attention to forward / backwards sway.
Describe the amount of sway you showed in the table below.
Eyes open
Eyes closed
Facing forward
Facing sideways
Explain how this test demonstrates the role of vision in balance.
Mini-Essays
On separate paper, write two essays about any two of the tests listed below:





Snellen vision test
Astigmatism test
Weber test
Rinne test
Viewing of the tympanic membrane and auditory canal
In each essay, you should



Describe the test and explain what disorders it might indicate
Describe and interpret your results
Explain how any disorders that can be detected by this test can be treated
Pre-Lab Questions
Achievement Level
0
1
2
3
Descriptor
The pre-lab questions were not completed before the lab began or little attempt has
been made to accurately answer the questions.
The answers to the pre-lab questions partially accurate.
The answers to the pre-lab questions were mostly accurate.
The answers to the pre-lab questions were completely accurate.
Group Work & Lab Skills
Achievement Level
0
1
2
3
Descriptor
Group members did not follow safe lab procedures.
Group members had difficulty working together. Scholars used equipment carefully
and followed directions.
Group members mostly worked together effectively during the lab. Scholars used
equipment carefully and followed the directions.
All group members worked together safely and effectively during the lab. Scholars
used equipment carefully and followed the directions.
Worksheet
Achievement Level
0
1
2
3
Descriptor
Little attempt has been made to accurately answer the worksheet questions.
The answers to the worksheet questions partially accurate.
The answers to the worksheet questions were mostly accurate.
The answers to the worksheet questions were completely accurate.
Essays
Achievement Level
0
1-2
3-4
5-6
Descriptor
Little attempt has been made to complete the essays
The scholar did not address all points of the essay OR the scholar had major
misunderstandings about how the tests are used.
The scholar correctly addressed most of the points in their essays, but had some
misunderstandings OR the essays demonstrated little use of appropriate scientific
language and/or the essays were not clearly written or organized.
The scholar used appropriate scientific vocabulary to clearly and thoroughly address
each of the following points in two well-organized essays:
 The scholar described the test and explained what disorders it might indicate
 The scholar described and interpreted his/her own results
 The scholar explained how any disorders that can be detected by this test can
be treated
Scoring guidelines
Achievement
level
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
Grade
100
98
96
94
92
90
87
84
81
78
75
72
69
65
60