Revaluing overselected stimuli: Effects of degree of posttraining extinction on stimulus overselectivity

When responding to a stimulus exerting overselective control over behavior is extinguished, control by underselected stimuli may emerge. We investigated how the degree of extinction influences control by underselected stimuli. Adult humans (N = 459) chose between rapidly presented compound S+ and S- stimuli in a simultaneous discrimination. Then, participants chose between individual compound-stimulus elements in an unreinforced testing phase. The S+ element that was chosen most often underwent revaluation, during which choice of that element was reinforced with a probability ranging from 0 (complete extinction) to 1 no extinction) in different groups. In post-revaluation retesting, choice of the overselected element was lower than in pre-revaluation testing; this decrease was greater when the overselected element had been reinforced with a lower probability during revaluation. For the underselected element, choice decreased when the overselected element was completely extinguished and increased when the overselected element was sometimes or always reinforced. This highlights the role of the contingency change in post-revaluation changes in stimulus control. Our findings are consistent with comparator theories of overselectivity and suggest that control by underselected stimuli may emerge after partial extinction of an overselected stimulus. Future studies should establish the generality of these findings with clinical populations displaying overselectivity.