In order to understand what was controlling this unexpected behavior of salivating when the laboratory assistants were seen, Pavlov placed an inexperienced (naive) dog in a harness and occasionally gave it small amounts of food powder. Just prior to placing the food powder in the dog's mouth, Pavlov sounded a bell, a buzzer, or some other auditory stimulus (Carlson, 1997).
At first, the dog showed only a startle response to the sound. The dog salivated only when the food powder was placed in the dog's mouth. After only a dozen or so pairings of the bell and food powder, the dog began to salivate when the bell rang (Carlson, 1997).