Learning involves relatively permanent changes in behavior or capacity that result from experience. There are two main theories of learning: association/stimulus-response theories which view learning as the strengthening of connections between stimuli and responses, and cognitive theories which focus on internal cognitive processes rather than external stimuli. Famous association theorists include Thorndike, Pavlov, and Skinner, while cognitive theorists include Köhler and Bandura. Key concepts in learning theories are conditioning, reinforcement, extinction, generalization, discrimination, and observational/social learning.