Observations and results
Did you and your partner usually catch the ruler around 15 centimeters (six inches)? What took so long?
On average, reaction time takes between 150 and 300 milliseconds. If that sounds like a long time, think about how much has to happen for you to react. When your eye sees the ruler falling, information travels from sensory cells called neurons from the eye to the brain's visual cortex, an area devoted to understanding what you see. Next, the motor cortex—the part of the brain that directs movement—has to send signals along your spinal cord and to your arm, hand and finger muscles, telling them to respond in the proper sequence to catch the ruler—quick! That's a lot happening in less than half a second—and a pretty amazing feat!
More to explore:
Experience versus Speed from Scientific American MIND
Brain Brakes Car Faster Than Foot from Scientific American
Reaction Time Test from the Human Benchmark
How fast are your reactions? from the BBC