You drop a hot potato long before you actually feel the pain that comes from burning your hand. That’s because as soon as you touched it, your nerves quickly sent a message saying, “too hot” to your spinal cord. The nerves in your spinal cord answered this message right away, they didn’t even wait for the message to reach your brain.
These nerves made you spread out your fingers so that you dropped the potato. You didn’t even have to think about spreading your fingers because the reaction was automatic. This kind of movement is called a reflex action.
There are many other kinds of reflex actions your body performs. If a light is flashed in your eyes, you will blink. If you sniff pepper, you will sneeze. And if someone scares you, you will jump. The muscles that make you blink, sneeze, or jump went to work even before your brain knew what was happening.