Classical conditioning and operant conditioning are two prominent theories of learning. Classical conditioning, studied by Ivan Pavlov, is a type of learning where a neutral stimulus becomes associated with a reflexive response through repeated pairing. Operant conditioning, developed by B.F. Skinner, is a type of learning based on the idea that behavior is shaped by its consequences. Behaviorist psychologists draw conclusions based on observations of what organisms do in their environment, and their theories include classical conditioning, operant conditioning, and other types of cognitive, observational, and social learning.