Classical conditioned reflex is a typical example, which includes repeatable neutral stimulus and unconditional stimulus. Unconditional stimulus (us) can cause unconditional response (UR) without learning. The relationship between unconditional stimulus and unconditional response is called unconditional reflex.
Conditional stimulus (CS) is the initial neutral stimulus (NS) that can cause conditioned response (CR), and it needs to be learned.
Conditional stimulation is psychologically related to immediate and long-term expectations, satisfaction and fear. The relationship between conditioned stimulus and conditioned response is called conditioned reflex. When an unconditioned stimulus is accompanied by a neutral stimulus repeatedly or violently, the neutral stimulus will become a conditioned stimulus and produce a conditioned reflex.