This was the context of Pavlov's speeches, delivered at the Women's Medical Institute in April and May 1918. The answers to all these questions, Pavlov told his audience, were evident in his lab results. By sounding a tone and then feeding a dog, the scientist explained, he established in the dog's brain an association between the tone and the food. Different animals, however, responded to such trials very differently. Well, one can say this is a businesslike dog.
Food is a serious affair and the animal aspires to it, prepares itself.
That is how it goes with serious dogs. In other dogs, however, the sounding of the tone only made them listless and sleepy, and only if you put the food in its mouth does the dog give a food reaction and begin to eat . . . You see that for some dogs the thought of food, even for one minute, is unbearable, they already need sleep. Dogs also displayed varying abilities to accomplish differentiation, the process by which they distinguished between related elements of their environment. For example, Pavlov would feed a dog after exposing it to a metronome beating at 40 beats per minute.