Testing Reaction Time with Rulers
Test your reaction time by catching a ruler.
Reaction time is a measure of how quickly an organism responds to some sort of stimulus & a change in the environment that an organism reacts to. The time it takes from when your eye first notices the ruler to when your arm catches the ruler is an example of reaction time. Even though stimuli travel very quickly along your nervous system as messages, your body doesn't react instantly. The ruler experiment is testing reaction time and voluntary movement.
What You Need
A ruler.
Safety Notes
Do not hold the ruler too close to your body to avoid dropping it on your feet.
What To Do
- Person 1 should hold the ruler vertically at the top end between their thumb and index finger. The ruler should be held
away from the body. - The person who wishes to test their reflexes (person 2) should put his/her thumb and index finger around the ruler at the bottom end (the 0 mark) but not touch it.
- Person 1 drops the ruler without warning.
- Person 2 tries to catch the ruler where it is caught.
- Repeat at least 3 times and get the average of the three measurements where the ruler was caught.
- The distance (cm) the ruler falls before being caught (if at all), is a measure of their reflexes. Check the chart to see how fast you reacted.
Discovery
Reaction time is a measure of how quickly an organism responds to some sort of stimulus – a change in the environment that an organism reacts to. The ruler experiment is testing reaction time and voluntary movement.
A reflex is an involuntary response that the body uses to protect itself. A reflex is faster than a reaction. Examples include blinking, withdrawal (i.e. when something is hot), or the rubber mallet below your knee at the doctor office (patellar reflex).
The nervous system helps information travel through your body. It consists of your five senses, your brain, your spinal column, and the nerves that connect them all together. As the ruler drops, your eyes send a message to your cerebrum in your brain through your nerves. Your cerebrum sends this information to the cerebellum, which then decides what to do. The cerebellum sends this decision as a message through other nerves to the arm and hand, activating the muscles used to catch the ruler. Of course, all this takes time!
The time it takes from when your eye first notices the ruler to when your arm catches the ruler is an example of reaction time. Even though stimuli travel very quickly along your nervous system as messages, your body doesn’t react instantly.
For more information about reaction time, and to calculate your reaction time, see:
What's Happening
Reaction time is a measure of how quickly an organism responds to some sort of stimulus – a change in the environment that an organism reacts to. The ruler experiment is testing reaction time and voluntary movement.
A reflex is an involuntary response that the body uses to protect itself. A reflex is faster than a reaction. Examples include blinking, withdrawal (i.e. when something is hot), or the rubber mallet below your knee at the doctor office (patellar reflex).
The nervous system helps information travel through your body. It consists of your five senses, your brain, your spinal column, and the nerves that connect them all together. As the ruler drops, your eyes send a message to your cerebrum in your brain through your nerves. Your cerebrum sends this information to the cerebellum, which then decides what to do. The cerebellum sends this decision as a message through other nerves to the arm and hand, activating the muscles used to catch the ruler. Of course, all this takes time!
The time it takes from when your eye first notices the ruler to when your arm catches the ruler is an example of reaction time. Even though stimuli travel very quickly along your nervous system as messages, your body doesn’t react instantly.
Resources
For more information about reaction time, and to calculate your reaction time, see: