Then, suddenly slam a book on a table to create a loud noise. Have a partner sit with his or her legs crossed so that his leg can swing freely. Hit his leg just below the knee with the side of your hand. This means that there is only 1 synapse in the neural circuit needed to complete the reflex. The tap below the knee causes the thigh muscle to stretch.
Information is sent to the spinal cord.
Another demonstration of these built-in capabilites is the blink reflex . Have a student stand behind a see-through barrier like a window or a wire screen. Throw a cotton ball at the person. This is the blink reflex and serves to protect our eyes from damage. The average person blinks about 12 times per minute.