Pavlov (1927) studied unconditioned reflexes in dogs like salivating in response to food. Later researchers like Watson, Raynor (1920) and Skinner (1957) studied conditioned learning through rewards and punishments in humans and animals. Observational learning theory proposes that behavior can be learned through observing and imitating others. Behavioral therapies for mental health issues are based on classical and operant conditioning principles like systematic desensitization to treat phobias. However, the behavioral approach is limited as it does not consider genetic or cognitive factors in learning and behavior.