Behaviorism is a theory that all behaviors are acquired through conditioning and interaction with the environment, without consideration of internal mental states. John B. Watson established behaviorism, which was influenced by Ivan Pavlov's experiments conditioning dogs to salivate when they heard a bell. B.F. Skinner expanded on this with operant conditioning, where behaviors are reinforced or punished to increase or decrease the likelihood of their recurrence. A classroom example is positively reinforcing good academic performance with rewards, while punishing late assignments with zeros to encourage timely submission.