Cutaneous Sensations
Purpose: In Activity A, you will test and document stimulus sensitivity using a medical monofilament,
studying whether or not certain parts of the hand and arm are more sensitive to single-point pressure
than others. In Activity B, you will study cutaneous sensitivity to hot and cold stimuli. In Activity C,
you will map and measure the receptor density and receptor field size of different parts of the body using
two-point discriminators to identify two-point thresholds.
Background: The skin is the largest sensory organ of the body. The skin has many receptor sites for
cutaneous sensations (from the Latin cutis, meaning "skin") and is sensitive to many different kinds of
stimuli, including touch, pressure, temperature, and pain. The ability to perceive these sensations is
determined by specific sensory receptors and their pathways to the brain. The distribution of receptors
varies at different locations on the body surface. Areas of the body such as the fingertips and the palm of
the hand contain a higher receptor density and can therefore sense stimuli more accurately. Give some
background information on free nerve endings, Meissner’s corpuscles and Pacinian corpuscles. (3 pts)
Hypothesis: none
Variables: Control set up: specific parts of the skin, and a stamped grid
Manipulated: temperature, specific parts of the skin
Response: you figure it out
Materials:
 Stamp pad and grid stamp
 Monofilaments
 Aluminum temperature probes
 Dry heat incubator
 Two point discrimination tool
Procedure: paraphrase the three activities (6 pts)
Activity A: Stimulus Sensitivity Testing
Each team (or pair) of students should have a Student Guide. Each individual student should have a Data
Sheet. Record the data provided by the test subject by coloring in the corresponding dot on the Data
Sheet each time a stimulus is felt by the test subject.
1. The test subject sits with blind fold over their eyes and with the stamped hand palm downward
and motionless on the desk. The experimenter begins with the grid labeled "Back of Hand."
2. The experimenter begins in one quadrant of the dot grid and gently touches each dot with the
medical monofilament. Hold the monofilament by the paper handle and touch it lightly to an ink
dot on the test subject's skin. The test subject reports whether or not he or she feels a stimulus.
3. Repeat this activity, touching the other dots on the grid, reporting the sensation, and recording
the response on the Data Sheet. Continue until all of the dots (or the required number of dots)
have been tested.
4. Repeat this procedure for the palm and forearm locations and record the results. Remember that,
in order to analyze and interpret data correctly, it must be organized, complete, and recorded
accurately.
5. Average the number of sensitive spots for each of the four stamp quadrants starting with the
upper left box and proceeding in a clockwise rotation. QUAD 1, QUAD 2, QUAD 3 and QUAD
4 for all your tested body areas.
Activity B: Temperature Sensation
Page 1 of 6
Each team (or pair) of students should have a Student Guide. Each individual student should have a Data
Sheet. Record the data provided by the test subject by coloring in the corresponding dot on the Data
Sheet each time a stimulus is felt by the test subject. There are two parts to this activity.
1. Get an aluminum temperature probe from the freezer of my small refrigerator. Make an ice water
bath and place the probe in the water bath. Let it cool further until it is icy cold.
2. The test subject sits with eyes blind folded and with the stamped hand palm downward and
motionless on the desk. The experimenter begins with the grid labeled "Back of Hand."
3. The experimenter begins in one quadrant of the dot grid and gently touches each dot with the
temperature probe. The probe should remain on each dot for about two seconds. The test subject
reports whether or not he or she feels a cool stimulus (don’t confuse cool sensation with pressure
sensation.)
4. Repeat this activity, touching the other dots on the grid, reporting the sensation, and recording
the response on the Data Sheet. Continue until all of the dots (or the required number of dots)
have been tested.
5. Replace the probe back in the ice bath periodically in order to keep it cold. Repeat this procedure
for the palm and forearm locations and record the results. Remember that, in order to analyze and
interpret data correctly, it must be organized, complete, and recorded accurately.
6. Repeat steps 1 through 5, this time using a warm temperature probe to map warmth receptors.
Give the sensor time to warm up and then follow the same protocol, mapping warmth receptors
for the back of the hand, the palm, and the forearm.
Activity C: Two-Point Discrimination
Each team (or pair) of students should have a Student Guide. Each individual student should have a Data
Sheet. Record the data provided by the test subject by filling in the blanks in the data table on the Data
Sheet. Test five different locations three times each. Gather data from the following body areas:
fingertip, palm, forearm, back of the neck, and back of the lower leg (calf).
1. The test subject sits with eyes closed and one hand palm upward and motionless on the desk. The
experimenter begins by testing the fingertip.
2. Start with the two points on the two-point discriminator touching each other. In increments of
1-2 mm, gradually increase the distance between the two points. Test the subject's skin after each
3. adjustment. Each time the two points are touched to the skin, ask the test subject whether he or
she feels only one point or two distinct points.
4. Repeat this procedure until the test subject reports feeling two distinct contact points. The
measurement at which two distinct points are felt is called the "two-point threshold." This value
is obtained by reading the number found between the two arrows in the middle of the sliding
scale on the two-point discriminator. Record the test subject's two-point threshold in the "Trial 1"
column of the data table.
5. Repeat steps 2 and 3, obtaining a two-point threshold measurement for the following areas of the
test subject's body: the palm of the hand, the forearm, the back of the neck, and the lower leg or
calf. Record each of these results in the "Trial 1" column of the data table.
6. Conduct two additional trials for each of these locations, following the procedure above. Record
the results in the "Trial 2" and "Trial 3" columns of the data table. Average the 3 trials and record
that information in the class data spreadsheet.
Page 2 of 6
Data Collection: (total of 15 pts)
You will need one data sheet (see last page of lab) per person (4 pts). You will need a data table with
every partners results in the ice vs hot warm activity. (4 pts) You need a class data table including the
statistical results for each of the Activities as directed in the data analysis or conclusion questions (7
pts).
Data Analysis: (total of 14 pts)
1. Find the average number of receptor sites located for each area that was tested. Construct a bar
graph using the class averages, that illustrates the data from both Activity A and Activity B.
Numbers of receptors should be on the Y axis and the body regions on the X axis. The legend
should identify what type of receptor was tested. (5 pts)
2. Compare the results if the different activities and determine if gender has a significant role in
receptor distribution. Don’t forget to tell me what t-test you used and explain if or if not, gender
had a significant affect. Cite and explain your results thoroughly. Highlight the those
significantly different cells in your data table. (5 pts)
3. Was anyone significantly different for these activities. Don’t forget to explain, statistically, why
they were significantly different and highlight them in your data table. (4 pts)
Conclusion: use class averages to answer the following questions; total of 29 pts
1. From activity A, compare the results for the different test areas. Using the class data,
determine if there is a significant difference in the fine touch receptor densities for the
regions you tested? This means you must do multiple t-tests; comparing hand to palm, hand
to forearm and palm to forearm. Cite and explain your results thoroughly. (6 pts)
2. From activity B, was there a significant difference between warm and cold receptors? You
need to do t-tests comparing warm hand to cold hand, hot palm to cold palm and hot forearm
to cold forearm. Treat these tests as if they were done before and after, i.e. you are using a
different t-test then the one used in conclusion question #1. Cite and explain your results
thoroughly. (6 pts)
3. From activity C, analyze the data from the three trials. Based upon this data, what inferences
can you make regarding receptor densities and receptive fields based on the two-point
threshold data? This means you must do multiple t-tests; comparing fingertip to palm,
fingertip to forearm, fingertip to neck, fingertip to calf etc.. There will be a total of 9 t-test
results. Cite and explain your results thoroughly. (12 pts)
4. Are some locations significantly more sensitive than others are? Hint: refer to two point
discrimination data to answer this question. (2 pt)
•
Don’t forget to critique the lab to see if there were directions that didn’t make sense or
procedural steps that will influence the results other than what we were manipulating. (2 pts)
•
Make suggestions to correct the errors listed above! (1 pt)
Page 3 of 6
Test Subject: _____________________
Cutaneous Sensations Data Sheet
Activity A: Stimulus Sensitivity Testing
Average # of
receptor sites
________
___________
____________
________
___________
____________
________
___________
____________
Activity B: Temperature Sensation
Warm Test:
Average # of
receptor sites
Cool Test:
Average # of
receptor sites
Activity C: Two-Point Discrimination Test
Location
Fingertip
Palm
Forearm
Back of the Neck
Lower Leg (Calf)
Trial 1 (mm)
Trial 2 (mm)
Trial 3 (mm)
Average (mm)
Page 4 of 6
Test Subject: _____________________
Cutaneous Sensations Data Sheet
Activity A: Stimulus Sensitivity Testing
Average # of
receptor sites
________
___________
____________
________
___________
____________
________
___________
____________
Activity B: Temperature Sensation
Warm Test:
Average # of
receptor sites
Cool Test:
Average # of
receptor sites
Activity C: Two-Point Discrimination Test
Location
Fingertip
Palm
Forearm
Back of the Neck
Lower Leg (Calf)
Trial 1 (mm)
Trial 2 (mm)
Trial 3 (mm)
Average (mm)
Page 5 of 6
Test Subject: _____________________
Cutaneous Sensations Data Sheet
Activity A: Stimulus Sensitivity Testing
Average # of
receptor sites
________
___________
____________
________
___________
____________
________
___________
____________
Activity B: Temperature Sensation
Warm Test:
Average # of
receptor sites
Cool Test:
Average # of
receptor sites
Activity C: Two-Point Discrimination Test
Location
Trial 1 (mm)
Trial 2 (mm)
Fingertip
Palm
Forearm
Back of the Neck
Lower Leg (Calf)
Trial 3 (mm)
Average (mm)
Page 6 of 6