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Published: May-2024 | Category: Secondary Science


A reaction time is the quickest time an individual can respond to a stimulus. A reaction time is the total time for a message travel up to the Central Nervous System [CNS] and come back again and produce a response. 

Reflex reactions are different from reaction times; they by-pass the brain to give a very quick response. You may be familiar with the eye blink response, knee jerk (as seen in many cartoons) and ankle twitch.

In This Activity

This activity involves quite a lot of brain power and has a conscious response to a stimulus. For example, saying OUCH!! to something that hurts is not a reflex, it has a bit of brain power involved. If you were hiding and hurt yourself, you could stop the OUCH! But, you can’t stop an eye blink.

Because of the way the body works you would be unlikely to see a reaction time below 0.02 seconds (unless there was a bit of cheating!).

In this activity your student investigators will be able to see how reaction times vary to different stimuli, and perhaps any other factors that you and they may think might be important. For example, is it true that sporty people have better reactions?

Learning Outcomes

  • Scientific method.
  • Creating and testing a hypothesis.
  • The fair test.
  • Observation.

You Will Need

  1. A data logger with a pair of external push button switch sensors (attached to the computer linked to your interactive whiteboard, projector or other large display)
  2. Software showing the product of the logger as a Time from A to B.
  3. A CD or something to hide the testers finger movements but allow the subject to see the light.
  4. Things and ideas to test that may alter reaction times, e.g. music, phones, flashing lights or any other distractor
  5. A long tape measure (e.g. a field tape).
  6. Some calculators (for extension work)

Download the full teachers worksheet here!

Products to help you achieve this activity:

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