Reaction Time Assignment
A child suddenly runs into the road in front of the car you are driving. A friend tosses you the book you just asked for. A frisbee flies towards your head as you are studying in the Dimple.
All of these situations require you to respond quickly, in order to avoid being injured or injuring someone else. How quickly we can respond in a given situation is a measure of our reaction time. Reaction time is a common variable measured in biopsychology. The speed with which we can detect a stimulus, decide whether or not (and how) to respond to it, and then issue that response can tell us a lot about how the brain works.
For example, how is it that a professional baseball player can hit a fastball? Consider that the average speed of a fastball pitch in professional ball is over 144 kilometers per hour, and that the distance between the pitcher's mound and home plate is only a little over 18 meters. That means that the batter has only about 0.4 seconds from the time the ball leaves the pitcher's hand to decide whether or not to swing at the ball!
Fighter pilots also must have very fast reactions--travelling at speeds of over 2500 km per hour (twice the speed of sound) means travelling about 700m every second! So splits of a second can make all the difference; you blink your eyes and you’ve moved an incredible 140m!
Could you respond to outside events with minimal delay and take appropriate action? In this investigation, we will describe the average reaction time of students in the class to a dropped ruler. Note that in this study, we are not asking any questions about cause and effect; rather, we are simply describing reaction time as it is displayed in this class and this situation.
Procedure:
1. Each team of 3-4 students should get one reaction time meter stick from the instructor. (If you do not have a reaction time meter stick, you can use a ruler that has inches or centimeters on it--you just need the conversion table mentioned below.) Each person in the team should have his or her own data sheet on which to record data. You can download a copy of the reaction time data sheet (In MS Excel) here. If you are using a conventional ruler, you can download a conversion chart of inches or centimeters to reaction time here.
2. Take turns acting as subject, experimenter, and data recorders.
3. Once you have decided who will be the first subject and the first experimenter, the experimenter should hold the meter stick near the top, letting it hang vertically.
4. The subject places his/her thumb and index finger over the "thumb line" on the reaction time ruler, ready to catch it when it falls. NOTE: the subject's fingers should NOT TOUCH the ruler! There should be about an inch of space between the subject's fingers and the ruler.
5. When the subject is ready, he or she should tell the experimenter to "go!" once the subject says to go, the experimenter may drop the ruler at any time within the following 10 seconds. At no time should the experimenter look at the subject. The subject should try to catch the ruler as soon as possible. [Hint: To prevent guessing, the experimenter should vary the time before letting go of the ruler].
6. When the reaction time ruler has been caught, the line under the middle of the subject's thumbnail should be estimated. This line represents the number of milliseconds that passed before the ruler was caught. Record this number in the appropriate place on your data sheet.
7. Each subject should be tested
10 times in a row. Then, calculate the average result (add all ten numbers
together and divide by 10). Record the average in the appropriate place
on your data sheet.
8. Repeat until you have tested each of your teammates. Compile your data so that each of you has all of the data the team collected. If instructed to do so, enter your team's data in the class spreadsheet on the computer at the front of the classroom.
9. Take a few minutes and discuss with your teammates what happened. What factors do you think might influence people's reaction time in this or any other study of the subject? How might you test your ideas?
10.Write up the reults of your
investigation using the format
given on the "Helpful Hints" website. Be sure to attach
your data sheet to your written summary.
Writing the Reaction Time Summary
For the next class meeting, you should bring a written summary of your investigation to turn in to your instructor. All summaries submitted in this class must be typed and double-spaced. They should also be short--aim for no more than 2-3 pages. Don't forget to add your name on the back of the last page, and to add and sign the Wheaton Honor Code Pledge.
Your summary should begin with an introduction, in which you briefly describe reaction time, and the purpose of this investigation (to describe reaction times of the students in our class). It should then contain a methods section, in which you describe your subjects and your procedure for collecting the data. Follow this section with "Results," in which you describe the average reaction times of yourself and your teammates, and include any data available on class average reaction time. Finally, finish your summary with a discussion section, in which you offer some interpretations of your data. Why do you think you obtained the results that you did? What factors do you think might influence reaction time? How might you test your ideas in a future study?
Be sure to attach your data sheet with a staple to your written summary! An assignment that does not include the data sheet will not be graded. Also, be ready to discuss in class your ideas about what might influence reaction time, and how we might test your ideas.
More on Reaction Time:
Read this review of reaction time studies by Robert Kosinski of Clemson University.
How quickly can you respond to a fastball pitch?