Russian physiologist Ivan Pavlov’s experiment on dogs is one of the most famous examples of classical conditioning. In these well-known investigations, minor surgery was performed on a dog so that its saliva could be measured. From there, the dog was deprived of food, a bell was sounded, and meat powder was placed in the dog’s mouth. The meat powder caused the hungry dog to salivate—an example of an unconditioned reflex. However, eventually, after many trials, the dog would salivate at the sound of the bell without meat powder being offered. This is classical conditioning, also called a conditioned reflex or classical Pavlovian conditioning. In fact, such conditioning is evident every day in many humans’ lives, such as advertising campaigns that link an unrelated stimulus with a desired behavior. For example, a beautiful woman in a beer commercial entices men to buy beer, or a commercial of a handsome man influences women to buy a certain perfume.