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Fast Food: Can Peppermint Improve Reaction Times?

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Did you know that some teachers give their students a peppermint candy on state testing days? Is it to give the kids sweet-smelling breath? Or are the teachers hoping for something more on the important testing day? In this human biology science fair project, you'll explore whether or not peppermint influences scores on different types of tests.


Areas of Science
Time Required
Long (2-4 weeks)
Material Availability
Readily available
Very Low (under $20)
No issues
Kristin Strong, Science Buddies Alumni
Ben Finio, PhD, Science Buddies


To determine if peppermint can improve reactions times during periods of mental fatigue.


Imagine that tomorrow is a big state testing day. You may feel a little nervous, and your teachers and parents have probably advised you to "get a good night's sleep" and "eat a good breakfast," so that you can do your best. The biggest predictor of success on a test is, of course, the amount of time you spend studying for it, but can other little things, like eating breakfast, give you an edge, too?

In this science fair project, you won't be looking at memory tests, but at reaction time tests, and investigating whether eating peppermint can improve reaction times when a person is tired, or under mental fatigue. Reaction time is the time between the start of a sensory stimulus and the time when a person responds to that stimulus. For example, if a person is told to push a button when he or she sees the color red flashed on a screen, the reaction time is the time between when red is first flashed on the screen and the time when he or she first pushes the button. During the reaction time, the person's visual system will see and identify the color red, and then the higher thinking centers will command the motor cortex, in the brain, to send a signal to the arm and hand muscles to push the button. That's a lot going on!

The sensory stimulus does not have to be a visual one, though. Reaction time can be measured as a response to other sensory stimuli, too, such as a sound or a touch. In fact, reaction times to sound have been shown to be faster, on average, than reaction times to visual stimuli. Reaction times have also been shown to be dependent upon many factors, such as a person's:

For example, reaction times continue to shorten as a child ages. Reaction times reach their fastest point sometime in a person's late 20's. After this age, however, reaction times slowly begin to increase until the 50's and 60's, at which point they begin to increase even more. Reaction times also lengthen if a person is sleepy or mentally fatigued.

a timeline showing reaction time.

a horizontal timeline showing a white circle, the circle changing to black, eyes detecting the black circle, the brain commanding muscles to move, and a user clicking a mouse button.

Figure 1. This drawing shows that reaction time is the time from the presentation of a stimulus (in this example, the stimulus is the black circle) to the time of a reaction to that stimulus (when the user clicks the mouse button).

In this science fair project, you will look at reaction times during a time of mental fatigue, and see if peppermint has the ability to improve those reactions times. Peppermint is currently used in some school districts in the United States as a snack on state testing days, in hopes that it will help improve test scores. Peppermint aroma has been studied to see if it can increase attention and focus, and even athletic performance. You will study peppermint candies to see if they improve the reaction times of volunteers at a time when they are most drowsy, right before bedtime. So find your favorite peppermint candy and find out if peppermint freshens your breath and your brain!

Terms and Concepts



This source describes how peppermint candies are used in some school districts:

This source describes how many factors—like age, gender, and handedness—can influence reaction times:

This source describes paired t-tests and gives four online sites for conducting these tests:

This science fair project was inspired by this resource:

Materials and Equipment

Experimental Procedure

Working with Human Test Subjects

There are special considerations when designing an experiment involving human subjects. Fairs affiliated with Regeneron International Science and Engineering Fair (ISEF) often require an Informed Consent Form (permission sheet) for every participant who is questioned. Consult the rules and regulations of the science fair that you are entering, prior to performing experiments or surveys. Please refer to the Science Buddies documents Projects Involving Human Subjects and Scientific Review Committee for additional important requirements. If you are working with minors, you must get advance permission from the children's parents or guardians (and teachers if you are performing the test while they are in school) to make sure that it is all right for the children to participate in the science fair project. Here are suggested guidelines for obtaining permission for working with minors:

  1. Write a clear description of your science fair project, what you are studying, and what you hope to learn. Include how the child will be tested. Include a paragraph where you get a parent's or guardian's and/or teacher's signature.
  2. Print out as many copies as you need for each child you will be surveying.
  3. Pass out the permission sheet to the children or to the teachers of the children to give to the parents. You must have permission for all the children in order to be able to use them as test subjects.
  1. Practice using this online reaction time test yourself. If you want, you can customize the test before you use it with your volunteers. For example, you can change the color of the circle, the messages that are displayed, or you can add more things (like other buttons) to the screen.
    1. To take the test, click the green flag. Click the circle as soon as it changes color, and the program will display your reaction time in seconds. Click the green flag again to start a new trial.
    2. This test is made with a programming language called Scratch. If you want to customize the test, first create an account at the Scratch website. Next, click the link for the code or the image below. Click the "Remix" button at the top of the page. This will create a copy of the code in your own account that you can edit. Watch the following video to learn how the code works and how to edit it.
click to edit code image
  1. Divide your volunteers into two groups: one with peppermint and one without. Volunteers with peppermint will suck on a peppermint candy while taking the reaction time test.
  2. Make a data table like Table 1 in your lab notebook. Add enough rows for all of your volunteers.
     Volunteer  Peppermint
    Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average
    Table 1. Example data table
  3. Figure out how you will have your volunteers take the test. Try to have your volunteers all take the test around the same time of day. You can have them do it on your computer, or you can send them a link to the test so they can do it on their own computers at home. To get the link you need to share:
    1. Make sure you are viewing the "Project Page" for the test and not the code. If you are viewing the code, click the "See Project Page" button at the top of the screen.
    2. Click the "Copy Link" button. This is the link you should send to your volunteers.
  4. Have each volunteer take the reaction time test five times. Record their reaction times in your data table. If your volunteers are doing the test at home on their own computers, ask them to write down their results and send them to you.
  5. Calculate an average reaction time for each volunteer. Do this by adding up their five reaction times and then dividing by five.
  6. Calculate an overall average reaction time for all of your non-peppermint volunteers. Do this by adding up all of their average reaction times, then dividing by the number of non-peppermint volunteers. Do the same for your volunteers with peppermint.
  7. Analyze your results.
    1. Make a scatter plot of your data. The horizontal axis should have two categories: peppermint and non-peppermint. Plot each volutneer's average reaction time as a separate point on the vertical axis.
    2. Plot the overall average for each category as a separate point (use a different shape or color, so you can tell the difference between the overall category averages and the individual volunteers).
    3. Is there a difference between your peppermint and non-peppermint volunteers? Does one group have a faster reaction time on average than the other? Is there overlap between the two groups?
    4. You may want to test whether there is a statistically significant difference between the averages for the two groups. See the Variations section to learn more.
icon scientific method

Ask an Expert

Do you have specific questions about your science project? Our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.


  • Conduct a paired t-test on your two columns of data. This test allows you to determine whether the difference between your two groups is statistically significant. You can read more about how to conduct a paired t-test at websites listed in the Bibliography, above, or you can often find one in software that handles spreadsheets. The null hypothesis is the statement that you will be testing with the paired t-test to see if the two data sets (reaction times with and without peppermint) are (statistically) the same. Your null hypothesis is that the mean difference between the paired measurements is zero. The paired t-test will return a p-value.
    1. If p < 0.05, then you can say that the two columns of data are significantly different and that the peppermint affected reaction times.
    2. If p > 0.05, then the two columns of data are not significantly different.

    The lower the p-value, the greater your statistical confidence that the data sets are different.
  • Reaction times have been shown to follow a circadian rhythm. Develop an experiment to determine if there is a correlation between reaction times and body temperature.
  • Develop an experiment to determine if reaction times have greater statistical variation in children than in adults. For each volunteer, you will need to collect all the reaction times from the game, not just the averages, for this variation.
  • To try other science fair projects about reaction times, try these Science Buddies science fair projects:


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General citation information is provided here. Be sure to check the formatting, including capitalization, for the method you are using and update your citation, as needed.

MLA Style

Strong, Kristin, and Ben Finio. "Fast Food: Can Peppermint Improve Reaction Times?" Science Buddies, 1 Mar. 2024, https://www.sciencebuddies.org/science-fair-projects/project-ideas/HumBio_p027/human-biology-health/can-peppermint-improve-reaction-times. Accessed 4 Mar. 2024.

APA Style

Strong, K., & Finio, B. (2024, March 1). Fast Food: Can Peppermint Improve Reaction Times? Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/HumBio_p027/human-biology-health/can-peppermint-improve-reaction-times

Last edit date: 2024-03-01
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