Adjunctive behaviour

Adjunctive behaviour occurs when an animal expresses an activity reliably accompanying some other response that has been produced by a stimulus, especially when the stimulus is presented according to a temporally defined schedule. For example, in 1960, psychologist John Falk was studying hungry rats that had been trained to press a lever for a small food pellet. Once a rat had received a pellet, it was obliged to wait an average of one minute before another press of the lever would be rewarded. The rats developed the habit of drinking water during these intervals, but their consumption far exceeded what was expected. Many consumed three to four times their normal daily water intake during a three-hour session, and some drank nearly half of their body weight in water during this time. Further research has revealed that intermittent food presentation to a variety of organisms results in an inordinately excessive consumption of water as well as other behaviours including attack, pica, escape, and alcohol consumption.