SaH: Reaction Time

Have you ever wondered how fast your brain can send signals? In this experiment, you will be reacting to a signal sent to your brain and trying to improve your reaction time. You will need a friend or family member to help with this one. Share a picture of you and your partner in action!



How fast is your reaction time?



  • Ruler
  • Partner to work with
  • Wall


What to Do

  1. One person holds the ruler flat against the wall with the 12” side at the top. The second person holds their finger at the bottom of the ruler, about ½” away from the wall.
  2. The first person should let go of the ruler.
  3. The second person should try to stop the ruler between the wall and their finger.
  4. The shorter the distance the ruler falls, the quicker the reaction time.

Which person has a quicker reaction time?

Do both of your hands have the same reaction time?

If you try the experiment multiple times, does your reaction time continue to improve?


What is Happening?

Human brains are divided into many parts that all work together. For this activity you are using multiple parts of your brain – one to see where the ruler is, another to process how the ruler is moving and yet another to move your finger to stop the ruler. You are testing how quickly all this information passes from your eyes, through your brain, and to your finger.


Activity add-ons:

Try this experiment with your eyes closed. Have your partner make a sound as they release the ruler. Is the reaction time of your eyes or ears faster?

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