Is Smiling Contagious? *

Areas of Science Human Behavior
Time Required Average (6-10 days)
Prerequisites None
Material Availability Readily available
Cost Very Low (under $20)
Safety Adult supervision is recommended when collecting your data.
*Note: This is an abbreviated Project Idea, without notes to start your background research, a specific list of materials, or a procedure for how to do the experiment. You can identify abbreviated Project Ideas by the asterisk at the end of the title. If you want a Project Idea with full instructions, please pick one without an asterisk.


You've probably observed from your own personal experiences that some actions are contagious. Yawning is a great example. When one person in a room yawns, several other people usually do, too. Coughing, clearing your throat, these are other actions that often seem contagious. But what about smiling? Have you ever walked down the street and had a random stranger smile at you? Did it make you happy? Did you smile back? In this science fair project, you'll investigate whether smiling is contagious. You'll need to think of a way to design your experiment. One option would be to take a walk around a park and keep track of how many people smile at you, and whether those numbers change based on whether you smile at them or not. Or maybe you want to see if smiling has a chain reaction by having a friend walk a little ways behind you and see if the number of smiles he or she receives changes depending on whether you smile at the passersby first. However you design your experiment, make sure you're observing many people so that you can draw accurate conclusions. The Science Buddies guide Sample Size: How Many Survey Participants Do I Need? will help you determine how many observations you need to make. So put on a smile, because science is fun!

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Science Buddies Staff. "Is Smiling Contagious?" Science Buddies, 28 July 2017, Accessed 14 Oct. 2019.

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Science Buddies Staff. (2017, July 28). Is Smiling Contagious? Retrieved from

Last edit date: 2017-07-28

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