Nervous System Lab
Problem: Is there a measurable difference between the rate at which one can process sensory
information obtained visually, orally, and tactually?
Procedure:
Visual
1. Obtain a meter stick.
2. Hold a meter stick vertically with the “0 cm” end down and approximately at waist height.
(The 100 cm end would be high in the air)
3. Have your partner hold her writing hand with her thumb and forefinger held even with the
bottom (0 cm end) of the meter stick with one digit on each side of it as if they were going to
squeeze it.
4. Prepare to drop the meter stick.
5. Drop the meter stick and have your partner try to catch it as quickly as she can. Don’t give
any verbal warnings of when you will drop it. Record the distance the meter stick fell before
your partner grabbed it by looking at the part of the meter stick their fingers grabbed.
6. Repeat this procedure until you have recorded ten data points. Then, switch positions and
repeat with your partner.
Auditory
1. Repeat the procedure above, but this time have the “catcher” close his or her eyes. The
dropper indicates when the meter stick is dropped by saying “Now”. It is very important that
the dropper says, “Now” exactly when the meter stick is dropped.
2. Repeat the exercise for the other partner.
Tactile
1. This time, the catcher closes his or her eyes again, and the dropper indicates the meter stick is
being dropped by tapping the catcher on the shoulder.
2. Repeat the exercise for the other partner.
Data
Visual Data
Person 1
Person 2
Auditory Data
Person 1
Person 2
Tactile Data
Person 1
Person 2
Analysis of Data:
The big question is how to make sense of all this data. For this, we will need to use a statistical
tool known as a two-sample t test. The two-sample t test allows you to determine if two sets of
data are statistically different. We can expect to get different means for each method, but can we
say that the difference in mean is a meaningful, valuable piece of data, or is simply the result of
chance (sampling error, the whole if-you-flip-a-coin-ten-times thing)?
Because this is a TWO-sample t test, we will only be able to compare two samples at a time.
Thus, we will need to repeat our calculations three times: 1) compare visual and auditory, 2)
compare visual and tactile, and 3) compare auditory and tactile.
SHOW ALL CALCULATIONS NEATLY ON A SEPARATE SHEET OF PAPER!
1. Calculate the mean of each category. USE YOUR CALCULATOR to do this. Record in the
table below.
2. Write the null hypothesis and alternative hypothesis in the data table below for each of the
three experiments.
3. Calculate the degrees of freedom for visual/auditory using the following formula:
Degrees of freedom = n1 + n2 – 2
4. Calculate and record the difference between the means.
5. Use the instructions at the end of the lab to enter your data into your calculator and calculate
the p value.
6. Record the data in your table below.
7. Use the p< 0.05 to accept or reject the null.
8. Repeat the entire procedure for visual and tactile, and for auditory and tactile.
Visual
Auditory
Mean (x)
Visual and Auditory
Null hypothesis
Alternative hypothesis
Degrees of freedom
Difference between the two means
P value calculated from calculator
Accept or reject null
Is there a statistical difference?
Is so, which is faster?
Visual and Tactile
Null hypothesis
Alternative hypothesis
Degrees of freedom
Difference between the two means
P value calculated from calculator
Accept or reject null
Is there a statistical difference?
Is so, which is faster?
Tactile and Auditory
Null hypothesis
Alternative hypothesis
Degrees of freedom
Difference between the two means
P value calculated from calculator
Accept or reject null
Is there a statistical difference?
Is so, which is faster?
Write 2-3 sentence conclusion on the results obtained in this experiment.:
Tactile
T test instructions for TI 83+
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Press stat
Edit should be highlighted, ENTER
In the column L1 enter a data point and ENTER
Continue to enter all 10 data points
In column L2 enter a data point and ENTER
Continue to enter all 10 data points
Press STAT
Tab over to TESTS at the top of screen
Move down to #4 2 sample T-Test
Enter
It comes up Data
Move the arrow down to u1 =/ u2
Enter
Move to pooled data YES
Enter
Move down to calculate
Enter
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x is given (mean). Record it
p value is given. Record it.
This is the chance that the differences between the group is just due to randomness. Therefore 1- p is the
chance you are sure that there is a difference between the data groups.
ex. P=.02 means 98% chance there is a difference.
Repeat this process or have your partners do it for the other 2 comparisons
Visual to auditory
Visual to tactile
Auditory to tactile
Determine which ones if any are significant in their impact on reaction time.