Reaction Time: The Ruler Drop Test Experiment

How fast can you react?
In this activity, volunteers participate in a simple ruler drop experiment and learn about the body’s response behind it. We are testing young versus old.

The neural pathway involved in a reaction time experiment involves a series of neural processes. This experiment does not test a simple reflex. Rather, this activity is designed to measure the response time to something that you see.

Catching a dropped ruler begins with the eye watching the ruler in anticipation of it falling. After the ruler is dropped, the eye sends a message to the visual cortex, which perceives that the ruler has fallen. The visual cortex sends a message to the motor cortex to initiate catching the ruler. The motor cortex sends a message to the spinal cord, which then sends a message to the muscle in the hand/fingers. The final process is the contraction of the muscles as the hand grasps the ruler.

A person’s reaction time depends on a couple of things that can be improved and a couple that cannot. Practice does make perfect because you can create a “muscle memory” that means you do not have to think so much to catch the ruler. But electrical signals to travel along your nerves are involuntary and you cannot control how quickly they occur.
• How fast is your reaction time?
• Does your reaction time improve with practice?
• Why was the ruler caught in the middle (after a lag period) rather than at the end (instantaneously)?
• What causes this hesitation?
• How can reaction time be improved?

What had to happen in your body for you to catch the ruler?
• Explain that in order to catch the ruler a lot of messages have to be passed along different nerves:
• The eye sees the ruler drop.
• The eye sends a message to the visual cortex in the brain.
• The visual cortex sends a message to the motor cortex in the brain.
• The motor cortex sends a message to the spinal cord.
• The spinal cord sends a message to the hand/finger muscle.
• The finger muscle contracts to catch the ruler.

This happens almost instantaneously. How fast it actually happens is called the reaction time.