Removing the opportunity to respond induces resurgence

Twenty-four rats were initially trained to press a target lever under a variable-interval 30-s schedule of food delivery. Then, responses on that lever were extinguished and responses on an alternative lever were reinforced under the same schedule. Finally, target responses continued to be extinguished for all rats. For one group of rats, extinction was also arranged for alternative responses. For two groups of rats, the lever on which alternative responses occurred was retracted. No food was presented to one of those groups and food was presented under a variable-time schedule to the other. In all groups, the rate of occurrence of the target response at the beginning of the final condition exceeded the rate of occurrence at the end of the second condition, indicating resurgence. The number of target responses during the final condition was highest in the group with the lever removed and food presented independently of responding, second highest in the group with the lever removed, and lowest in the group with both levers present and no food delivered. These findings demonstrate that removing the opportunity to emit an operant response can induce resurgence, even when the stimulus that maintained such responding continues to be presented. Possible clinical implications of these findings are discussed.