Name: ___________________
Period: _____
Measuring Reaction Time
A stimulus is anything that can cause a reaction. When you sense a stimulus, an
electrical impulse travels from the sense organ through your nerves to your brain.
After a decision is made, other impulses travel from your brain to various
muscles, and you respond.
In some cases, the nerve impulse does not need to be interpreted by your brain
for you to respond. These reactions are called reflexes and happen much more
quickly than conscious decisions. Some of the factors that influence the reaction
time for these reflexes can be investigated with this Gizmo.
On the Computer:
Go to the website: www.explorelearning.com and click on Browse Gizmos.
Next, click on Biology, and then on Human Perception and Behavior. Find “Sight
vs. Sound Reflexes” and click on Launch Gizmo.
1. Read the Gizmo instructions. You will be testing your reaction time to
sight and sound stimuli. Set up your first test: Sight, Circle, Red (this
should be the default setting). Click “Start” and complete the test.
2. What was your average (mean) reaction time? ______________
3. What was your fastest reaction time? _____________
Slowest? ____________
Did you make any mouse-clicking errors? _____________
4. Click on “New Exam” to set up your next test: Sound, Thrump. Click
“Play” so you know what to listen for. Click “Start” and complete the test.
5. What was your average (mean) reaction time? ______________
6. What was your fastest reaction time? _____________
Slowest? ____________
Did you make any mouse-clicking errors? _____________
7. Click on “New Exam” to set up your next test: Sight and Sound. Click
“Start” and complete the test.
8. What was your average (mean) reaction time? ______________
9. What was your fastest reaction time? _____________
Slowest? ____________
Did you make any mouse-clicking errors? _____________
10. On the area of the gizmo that has the directions, click on the tab that says
“Table.” Describe your data – how does your reaction time to sound
compare to your reaction time to sight?
11. For your last test, select sight and sound, and set all stimuli at “Random.”
Click “Start” and complete the test.
12. What was your average (mean) reaction time? ______________
13. What was your fastest reaction time? _____________
Slowest? ____________
Did you make any mouse-clicking errors? _____________
14. Compare your results of the “random” test to the other three tests. Was
this more difficult? Explain.
In the Lab:
1. While you hold the 100-centimeter end of the meterstick, have your partner
position his or her thumb and forefinger around the zero end. Make sure that
your partner does not touch the meterstick.
2. Instruct your partner to concentrate on catching the meterstick as soon as you
drop it. You should move only the thumb and forefinger to catch the
meterstick.
3. When you are ready, drop the meterstick between your partner's fingers.
4. Note the measurement on the meterstick at the point at which your partner's
fingers caught the meterstick. Record this distance in centimeters in the
data table.
5. Repeat steps 1 through 5 four more times.
6. Switch roles and repeat steps 1 through 6.
7. Choose two of the following distractions: (circle and number your two
distractions)
 visual cue only
 auditory clue only
 kinesthetic clue only
 using the opposite hand
 left eye covered
 right eye covered
8. Repeat steps 1-6, except this time your partner is distracting you in the first
manner that you have chosen.
9. Repeat steps 1-6 again, this time with the second form of distraction.
Observations:
Data Table:
Trial
Distance Meterstick Falls (cm)
Without Distractions
With Distraction #1
With Distraction #2
1
2
3
4
5
Average
Analysis:
1. How did your average distance without distractions compare with your
average distance with distractions?
2. Which distraction was more effective – distraction 1 or distraction 2? Explain.
3. Describe two situations in which quick reflexes would be an advantage.
4. Alcohol is a depressant that slows the activity of the nervous system. Why is
it dangerous for a person to drive an automobile while under the influence of
alcohol?
5. Do you think it would be possible for a person to decrease his or her reaction
time (to react faster)? If so, how?