Final answer:
Pavlov accidentally discovered classical conditioning while studying the digestive processes of dogs. He observed that the dogs began to salivate not only at the taste of food but also at various other stimuli. This led him to realize that an organism has unconditioned and conditioned responses.
Step-by-step explanation:
Pavlov accidentally discovered classical conditioning while studying the digestive processes of dogs. Initially, Pavlov was measuring the amount of saliva produced in response to various foods. However, over time, he observed that the dogs began to salivate not only at the taste of food but also at the sight of food, the sight of an empty food bowl, and even at the sound of the laboratory assistants' footsteps. Through his experiments, Pavlov realized that an organism has two types of responses to its environment: unconditioned (unlearned) responses, or reflexes, and conditioned (learned) responses.