Stress increases behavioral resistance to extinction.

Behavioral persistence is required to reach a goal but may impede adaptations to changing environments. Given the well-documented effects of stress on learning and memory processes, we asked here whether stress affects the persistence of behavior. Participants were exposed to stress or a control condition before they learned an instrumental action to gain a food reward. During learning, we presented several extinction blocks in which the food reward was not presented. Stress rendered participants' responding shortly after initial learning insensitive to the extinction procedure. Overall learning curves remained unaffected. Thus, the present findings suggest that stress increases the resistance of behavior to extinction. The cause of the behavioral persistence after stress may be its habitual form.