Schedule-induced polydipsia consists of a pattern of post-food drinking that occurs when rats are intermittently fed small pellets of food. Rats are typically given a food pellet once a minute for 30-60 minutes per day. After a few of these sessions, most rats will drink following each food pellet delivery like the rat in the movie above. The rats do not have to be food or water deprived. Essentially, the repeated feedings turn drinking into a powerful reward through a process known as "sensitization." In sensitization, repeatedly eliciting the same reflex, in this case the normal eat-drink pattern shown by rats, can cause the reflex to reach exaggerated levels. Allergies are a form of sensitized reflex.

The water becomes such a powerful reinforcer that if the food and water are placed at opposite ends of a runway, the rat will run from one side to the other alternately eating and drinking. However, if the rat doesn't receive a small food pellets, it will drink normally. Schedule-induced drinking can be controlled by the same drugs that control obsessive-compulsive behavior in humans. This leads us to believe that schedule-induced drinking and some kinds of compulsive behavior may be the same behavior manifested in different ways. Schedule-induced behavior is sometimes also called "adjunctive-behavior."

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