1) Ivan Pavlov conducted experiments showing that dogs could be classically conditioned to salivate in response to a stimulus like the ringing of a bell through repeated pairing with food, known as classical conditioning. 2) B.F. Skinner expanded on Pavlov's work, applying classical conditioning to human behavior modification using positive and negative reinforcement. 3) Albert Bandura focused on social learning theory and how people learn behaviors by observing others.