喂狗的過(guò)程中，在給肉（無(wú)條件刺激）前加入鈴鐺刺激（條件刺激），狗會(huì)逐漸習(xí)得二者之間的聯(lián)系，從而在鈴鐺響起時(shí)也會(huì)流口水（條件反射）。

實(shí)驗(yàn)發(fā)現(xiàn)有三：

1. 習(xí)得的速度取決于兩點(diǎn)，一是刺激的明顯與否; 二是條件刺激和無(wú)條件刺激（即鈴聲與給肉）的間隔時(shí)間，間隔時(shí)間越短，習(xí)得越快。

2. 所習(xí)得的條件反射很容易消失，只響鈴而不給肉幾次后，狗就不會(huì)對(duì)響鈴刺激分泌唾液。但當(dāng)重新結(jié)合兩個(gè)刺激時(shí)，這種習(xí)得又很容易重新出現(xiàn)。

3. 習(xí)得可被泛化，即狗會(huì)對(duì)與鈴聲相似的刺激做出反應(yīng)；狗也可學(xué)會(huì)區(qū)分刺激，只對(duì)正確的刺激產(chǎn)生反應(yīng)。

When continuosly combine?feeding (unconditioned?stimulus, US) with a bell ringing (conditioned stimulus, CS), the dog would learn to salivate alone with the sound of the bell. It is called the learning of conditioned response (CR).

Pavlov's experienment found that

1. The rate of acquisition is dependent on the noticeability of the stimulus, and?also the time between the neutral stimulus?(aka the conditioned stimulus designed by the researcher, in this case, the bell ringing) and the unconditioned stimulus. The shorter the latter one is, the quicker the acquisition would be.

2. The conditioned response is vulnerable to extinctioin. Once the researcher stop to feed the dog and only ring bell, the dog would stop to salivate. But if the combination of US and CS appear again, the learing would recover.

3. There are generalization and discrimination for the stimulus learning. The dog would response to similar stimulus (e.g. ringtone on the phone) and was able to only react to the right stimulus once trained.

參考：

Classical Conditioning StatPearls [Internet], NCBI book shelf