Conditioned reflex is an acquired reflex gradually formed in the course of life after birth. It is done through a certain process on the basis of unconditional reflex and with the participation of cerebral cortex. It is a kind of higher nervous activity and the basic way of higher nervous activity.

For example, a person who has eaten delicious food many times will drool at the sight of it. This is done on the basis of eating delicious drooling, so it is a conditioned reflex.

There are two kinds of conditioned reflex, one is the conditioned reflex caused by the direct stimulation of the five senses, which is called the first signal system reflex, and the first signal system reflex is the desire to quench thirst; The other is the word conditioned reflex, which is called the second signal system reflex, such as "Speaking of Mei Jinsheng".