Van H. Blog Post 3: Adjunctive Behavior in Rats


What is Adjunctive Behavior? 

Adjunctive behavior is the excessive pattern of behavior that emerges due to the reinforcement of another behavior. Simply out, because of one behavior, another behavior emerges as a result. 

An example of adjunctive behavior, which is also known as schedule-induced behavior, is an experiment with rats. In this experiment, conducted by psychologist John Falk, trained rats to press a lever for food. The food however, was dispensed on an intermittent schedule. To combat this, the rats would drink water during the duration of waiting before pressing the lever for more food pellets. 

The act of drinking water to combat hunger, is the behavior that emerges in adjunction to pressing the lever for food, which is the original act. Within this experiment there were a couple distinction Falk had made about the experiment; 

  • Adjunctive behavior occurs within the period following the consumption of the pellets. This meant that the rats would eat the food pellets instantly as it was delivered, and then quickly went to drink water.
  • Adjunctive behavior is affected by levels of deprivation. The more hunger deprived the rats were, the more they drank!
  • Adjunctive behaviors can function as reinforcers. In other words, using adjunctive behavior, it can act as a reinforcer for an additional behavior. This means that not only would the rat be able to press the lever for food, it can also be trained to press the lever for water. 
  • In adjunctive behavior, is an optimal time between the reinforcer. In this study, there were varying intervals between 5 seconds and up. The optimal time for the rats to engage in adjunctive behavior ranged between 1 to 3 minutes. 


Honey, P., Powell, R., & Symbaluk, D. G. (2016). Introduction to learning and behavior (5th ed.). CENGAGE Learning Custom Publishing

Killeen, P.R., Pellón, R. Adjunctive behaviors are operants. Learn Behav 41, 1–24 (2013).