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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)
An introduction to statistics.
Material Availability
All volunteers must have access to a personal computer with Internet access.
Very Low (under $20)
No issues

Kristin Strong, 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? If you want to watch how a couple of students investigated whether eating breakfast could improve their scores on a memory test, click the DragonflyTV video link in the Bibliography, and join Cameron and Ashley as they test their entire classroom.

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 illustrates the process of reacting to a visual stimulous

Illustration showing reaction time to a stimulus. First, a blank screen is presented to a user. A red screen is then presented to the user (when measurement of the reaction time begins). In the next sequence, the red screen is detected by the visual system. The brain commands the arm and hand muscles to move. The final tick in the timeline shows a hand pushing a button (when measurement of the reaction time ends).

Figure 1. This drawing shows that reaction time is the time from the presentation of a stimulus (in this example, the stimulus is the red screen) to the time of a reaction to that stimulus (when the hand pushes the 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 source uses a stoplight for a reaction time test:

This science fair project was inspired by this resource:

Materials and Equipment

Experimental Procedure

  1. The first day, have your volunteers familiarize themselves with the Online Reaction Time Test by taking the test a few times. In this reaction time test, when the light turns green, the volunteer clicks on a button, and the reaction time is recorded and displayed. After five tries, the volunteer's average is displayed. This test does not allow a person to "jump the gun" and press the button too soon.
  2. The second day, give each of your volunteers a peppermint and have them each take the online reaction time test right before they go to bed. Ask them to
    1. Take the full test two times first for practice.
    2. Take the full test a third time and record their average reaction time on a piece of paper to give to you.
    3. Take the full test a fourth time, but this time have your volunteers put a peppermint candy in their mouths right before they take the test. Ask them to again record their average reaction time on a piece of paper to give to you.
    So, you should be getting two scores from each volunteer: one score from when they took the test before bedtime without the use of peppermint, and another score from when they took the test before bedtime while eating peppermint.
  3. After all the volunteers have been tested, you should have two bedtime reaction time scores from each volunteer—one from a trial without the use of peppermint, and one from a trial with the use of peppermint. Enter the reaction times from your volunteers into a spreadsheet program, like Microsoft Excel.
    1. In the first column, enter the game score (the average reaction time) when no peppermint was being eaten.
    2. In the second column, enter the game score when the volunteers were eating a peppermint as they took the reaction time test.
    Be sure that each row has reaction times for the same volunteer. For example, row 1 should have reaction times only for volunteer 1. Row 2 should have reaction times only for volunteer 2.
  4. Conduct a paired t-test on your two columns of data. 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. Paired t-tests are often used in situations where you are measuring one variable, like body temperature, and have two points of observation in the same person; for example, both before and after a medical treatment to lower body temperature. People react differently to the same treatment. Some may show a big response, while others may show little response. The paired t-test is a powerful test when the difference in the measurement variable between the before and after groups is small compared to the variation within a group.
  5. 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 before and after the 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.
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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.


  • 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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MLA Style

Science Buddies Staff. "Fast Food: Can Peppermint Improve Reaction Times?" Science Buddies, 20 Nov. 2020, https://www.sciencebuddies.org/science-fair-projects/project-ideas/HumBio_p027/human-biology-health/can-peppermint-improve-reaction-times. Accessed 31 Mar. 2023.

APA Style

Science Buddies Staff. (2020, November 20). 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: 2020-11-20
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