ivan pavlov was a Russian psychologist who mainly focused on classical conditioning. The experiment he conducted involved a dog, a bell, a saliva counter machine, and food. it came to be known as Pavlov's dog. anyways in this experiment he placed the dog where a food dish was and placed a machine in its mouth to see how much the dog would salivate. he would ring the bell and food would be produced. this made the dog salivate. they kept on ringing the bell and giving the dog food. eventually the dog associated the sound of the bell to the food appearing and once the bell went off the dog started to salivate. and this is basically what classical conditioning is about. sorry if it's a bit long.