# Stimulus and Response

This experiment will evaluate which sense produces the fastest response time: hearing, touching, smelling or seeing.

### Research Questions:

• Which sense elicits the fastest response time?
• Do the observed reaction times differ between male and female test subjects?

Which sense would you rely on if you needed to react quickly: sight, hearing, smell or touch? This experiment will evaluate which of these senses sends the fastest message to the brain and produces the quickest response.

### Materials:

• Calculator
• Meter stick
• Blindfold
• Test subjects (approximately 10 males and 10 females)
• Notebook for recording results

### Experimental Procedure:

1. Place your thumb and index finger above the 100 centimeter mark on the meter stick. For each test subject, perform the following steps:
2. Ask the test subject to place his or her thumb and forefinger on either side of the meter stick at the 0 centimeter mark. When you drop the stick, the test subject will attempt to catch it by closing his or her thumb and forefinger.
3. Test reaction time through vision first. Drop the meter stick and record the distance (in centimeters) that the stick falls before the test subject is able to stop it.
4. Perform five trials and calculate the average score.
5. Repeat the test using a blindfold to evaluate reaction time through hearing. Say the word, “DROP” when you let go of the meter stick.
6. Perform five trials and calculate the average score.
7. Repeat the test using a blindfold to evaluate reaction time through the sense of touch. Touch the shoulder of your test subject as you drop the meter stick.
8. Perform five trials and calculate the average score.
9. Repeat the test using a blindfold and scented candle. Place the candle directly under the nose of your test subject as you drop the meter stick.
10. Perform five trials and calculate the average score.
11. Repeat steps 2-10 for many male and female test subjects.
12. Evaluate your data and calculate each participant’s average reaction time for each sense. Use the formula: d=0.5a*t2. Solve for t when d equals distance traveled by the meter stick and a equals the acceleration due to gravity constant (9.8 meters per second squared).
13. Which sense leads to the fastest response time? Do you observe differences among male and female participants?

Terms/Concepts: senses, reaction time

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