Devaluation of a conditioned reinforcer requires its reexposure.

A change in motivational state does not guarantee a change in operant behaviour. Only after an organism has had contact with an outcome while in a relevant motivational state does behaviour change, a phenomenon called incentive learning. While ample evidence indicates that this is true for primary reinforcers, it has not been established for conditioned reinforcers. We performed an experiment with rats where lever-presses were reinforced by presentations of an audiovisual stimulus that had previously preceded food delivery; in the critical experimental groups, the audiovisual stimulus was then paired a single time with a strong electric shock. Some animals were reexposed to the audiovisual stimulus. Lever-presses yielding no outcomes were recorded in a subsequent test. Animals that had been reexposed to the audiovisual stimulus after the aversive training responded less than did those that had not received reexposure. Indeed, those animals that were not reexposed did not differ from a control group that received no aversive conditioning of the audiovisual stimulus. Moreover, these results were not mediated by a change in the food's reinforcement value, but instead reflect a change in behaviour with respect to the conditioned reinforcer itself. These are the first data to indicate that the affective value of conditioned stimuli, like that of unconditioned ones, is established when the organism comes into contact with them.