Extinction in psychology refers to the gradual weakening and disappearance of a behavior that was previously learned by association with another event. It is a behavioral phenomenon observed in both operantly conditioned and classically conditioned behavior). In classical conditioning, extinction occurs when the animal is re-exposed to the conditioned cue or conditioned context in the absence of the unconditioned stimulus. As the animal learns that the cue or context no longer predicts the coming of the unconditioned stimulus, conditioned responding gradually decreases or extinguishes). In operant conditioning, extinction refers to the process of no longer providing the reinforcement that has been maintaining a behavior. For example, a child who climbs under his desk, a response which has been reinforced by attention, is subsequently ignored until the attention-seeking behavior no longer occurs).

Extinction is considered successful when responding in the presence of an extinction stimulus is zero). When a behavior reappears again after it has gone through extinction, it is called spontaneous recovery). Extinction is not an unlearning process, but rather a form of new learning called extinction learning. Instead of erasing previous learning, the individual learns a new association.

Extinction can also occur with people. For example, in the case of learning a fear reaction in a place where a distressing event has occurred, extinction may happen if the person practices exposure to the location and learns that they are safe. The involuntary reaction to the setting may become extinct, and the person might go there without having any physical or emotional reaction.