In the video, Christopher and Zahabiya asked their friends to take their pulse rates before and after going on three different rides at their local amusement park. They also asked them to rate each ride according to how scary they thought they were. They found their friends' heart rates increased the most after riding on the ride that seemed the scariest. So their experiment showed a direct correlation between level of fear and increased heart rate.

Scientists have known for a long time that emotions like fear, anger, frustration, and anxiety cause the body to produce an automatic "flight or flight" response. This involves nerve and chemical signals that fire instant messages from the amygdala, a peanut-sized structure deep within the brain, to the heart, lungs, and other organs of the body whenever we sense fear or strong emotions. Additional nerve groups, called the sympathetic system, originate within the brain stem's medulla region and use adrenaline-like chemicals to stimulate the heart and accelerate its rhythm. Neighboring nerve fibers of the parasymphathetic system provide inhibitory signals to the heart and other organs to calm things down again, so we don't stay in a constant state of heightened alert. The balance between these two systems provides the right mix of up and down responses that keeps us safe and aware when danger is near or stress is present, and relaxed and calm after the stressful situation subsides.

You'll learn more about the relationship between emotions, brain, and body once you start this project. In the next section, we've included some suggestions for topics to research before you start your experiment so that you'll have more background and a better understanding of the science related to heart rate and the physiology of fear. You'll also see suggestions for other types of experiments to do in the Variations section below in case you don't have easy access to a great amusement park to run your tests.

Good luck, have fun, and let the screams begin!

Terms, Concepts, and Questions to Start Background Research

To do this project, you should do research that enables you to understand the following terms and concepts:

• Pulse
• Heart rate
• Fear
• Physiology of fear
• "Fight or flight" response
• Adrenaline
• Amygdala
• Medulla
• Sympathetic nervous system
• Parasympathetic nervous system

Questions

• What are you measuring when you take your pulse? What is a typical resting pulse?
• How is heart rate influenced by emotions like fear?
• What happens in the brain and body when we feel afraid?
• What causes the heart rate to increase during a "fight or flight" response?
• What are the sympathetic and parasympathetic nervous systems?
• How do the sympathetic and parasympathetic systems interact to produce changes in our bodies during emotional and nonemotional times?
• What is the amygdala and what does it do?

Bibliography

• Useful website that explains heart rate and how to measure pulse:
  NEMA, 2003. "What you Should Know About Your Heart Rate or Pulse," National Emergency Medicine Association [accessed May 16, 2007] http://www.nemahealth.org/programs/healthcare/heart_rate_pulse.htm.
• Company website with a brief introduction to neural and chemical changes in the brain and body that affect heart rate:
  FitMed Inc., date unknown. "Ways to Change Your Heart Rate," FitMed Inc. [accessed May 16, 2007] http://www.heartmonitors.com/exercisetips/changing_heartrate.htm.
• Brief explanation of the brain's response to fear:
  Arendal, L, 2000. "The Emotional Brain," Brain Connection website [accessed May 16, 2007]. http://www.brainconnection.com/topics/?main=fa/emotional-brain.
• Descriptions of basic brain anatomy and function including labeled images of the human brain:
  Serendip, date unknown. "Brain Structures and their Functions," Serendip website of Bryn Mawr College [accessed May 16, 2007] http://serendip.brynmawr.edu/bb/kinser/Structure1.html.
• TPT, 2006. "Roller Coasters by Christopher and Zahabiya," Twin Cities Public Television [accessed on May 08, 2007] http://pbskids.org/dragonflytv/show/rollercoasters.html.

Materials and Equipment

To do this experiment you will need the following materials and equipment:

• At least 10 friends to be volunteers in your experiment (more is better)
• Amusement park with at least two or three very fast, thrilling rides
• Watch
• Notepads or paper
• Pencils or pens

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Experimental Procedure

1. Recruit at least 10 friends or family members to be volunteers for your study.
   1. Tell them the day for your experiment and explain that you will be asking them to ride some fun but potentially scary rides at your local amusement or theme park.
   2. For tips on how to do experiments with volunteers, see the following Science Buddies resources:
      • Sample Size: How Many Survey Participants Do I Need?.
      • For ISEF-affiliated science fairs, studies involving human subjects require prior approval. For more information, see Projects Involving Human Subjects.
2. Practice taking your pulse. For details on how to take your pulse, you can go to http://www.nemahealth.org/programs/healthcare/heart_rate_pulse.htm.
3. Before the day of your experiment, you might visit the amusement park and scout out the rides to choose those you will want to include in your experiment. Try to select three rides that vary in speed and scariness, and even consider including one ride that is very calm and slow so you have a broad range of rides in your experiment. Check your own pulse rate before and after the rides that you choose to see how you respond to them.
4. The day of your experiment, gather your friends at the amusement park and remind them of your plan. Teach them how to take their pulse and have them record their resting pulse rate a couple of times for practice.
5. Now, the fun begins! Have your volunteers ride the three rides you selected. You can call them rides A, B, and C. Each time ask your volunteers to take and record their pulse before getting on the ride and then again as soon as they can after they get off.
6. Be sure to have them stand still or sit a few minutes before getting on the next ride so that their heart rates have time to return to normal.
7. Ask your volunteers to also rate each ride A, B, and C from 1 to 5 for "thrill factor," where 1 is the least scary and 5 is the most scary.
8. After the three rides, collect the volunteers' data.

1. Determine the change in pulse rate for each volunteer for each ride by subtracting their pulse rate before the ride from their pulse rate after the ride.
2. Calculate the average change in pulse rate for all volunteers for all three rides.
3. Add up the volunteers' "thrill factor" ratings for each ride and calculate the averages for all three rides.
4. Make a bar graph with three bars showing the average change in pulse rate for rides A, B, and C. On a separate bar graph use three bars to show the average "thrill factor" rating for rides A, B, and C.
5. Do you see any differences in the average change of pulse rate between the three rides?
6. Do you see any differences in the average "thrill factor" between the three rides?
7. Is there any correlation between pulse rate and scariness of the rides?

Variations

• If you don't have an amusement park close by, you can still do an experiment to evaluate the connection between emotions and heart rate. Try using short videos or sections of movies as your stimulus for fear or excitement. You could choose a scene from a scary movie or an exciting sports event, for example. As in the original experiment, ask your volunteers to practice taking their pulse rates before watching any video and then before and after each video screening.
• Would blood pressure be a good measurement of fear? Purchase inexpensive blood pressure monitors and use them to record the volunteers blood pressure before and after each ride. Compare your blood pressure data to the pulse rate data of the original experiment.
• Try a more long-term experiment for yourself or with a few friends. Purchase inexpensive wrist heart monitors to wear and record pulse rates during several hours per day. Keep a log of your activities and feelings every hour during the same time period. Perhaps repeat the monitoring of heart rate and logging of activities and emotions for a few days in a row. At the end of each day, note any changes in heart rate and also any highs or lows in activity level or emotion. Do you see any correlations between activity level or emotional state and pulse rate?
• For more Science Buddies projects related to heart rate and exercise, see
  • Heart Rate Recovery Times, and
  • Heart Health: How Does Heart Rate Change with Exercise?.

• For more science project ideas in this area of science, see Human Behavior Project Ideas.

Credits

Darlene E. Jenkins, Ph.D.

Sources

The idea for this project came from this DragonflyTV podcast:

• TPT, 2006. "Roller Coasters by Christopher and Zahabiya," Twin Cities Public Television http://pbskids.org/dragonflytv/show/rollercoasters.html.

Last edit date: 2008-06-17 00:00:00