Operant conditioning and classical conditioning are two major concepts in behaviorism. Operant conditioning involves using rewards and punishments to shape behaviors, while classical conditioning uses association to link stimuli and responses. Some classic studies that demonstrate these principles include Pavlov's dogs, which showed classical conditioning, and Little Albert, which showed a phobia could be conditioned in a human. Behaviorism takes a scientific approach but has been criticized for ignoring internal mental processes and long-term effectiveness of only targeting behaviors.