A previous study reported that explicitly unpairing a conditioned stimulus with an unconditioned stimulus generates the inhibitory property of the conditioned stimulus, as assessed by the retardation task, in an appetitive conditioning setting. This study conducted further experiments to demonstrate the conditioned inhibition induced by explicitly unpaired (EUP) training using the superconditioning and summation tests. In Phase 1, rats subjected to the EUP procedure received training in which light and food were explicitly unpaired. In Phase 2, rats in the EUP group for the superconditioning were trained with pairings of a light-tone compound and food. During the test phase, food-cup responses to either light or tone were measured. Food-cup responses to the tone in the EUP group were significantly higher than those in three control groups designed to rule out alternative explanations. For the summation test, rats in the EUP group underwent the same Phase 1 training as the superconditioning group, followed by Phase 2, which involved pairing the tone with food. In the test phase, food-cup responses to either the tone or the light + tone compound were measured. Food-cup responses to the tone in the EUP group were higher than those in the control group, but no difference was observed between the EUP and control groups for responses to the compound stimulus. These results indicate that EUP of the conditioned stimulus and unconditioned stimulus effectively generates superconditioning in appetitive conditioning. Superconditioning may provide a useful approach for investigating the neural mechanisms underlying appetitive conditioned inhibition. (PsycInfo Database Record (c) 2026 APA, all rights reserved).
Kim et al. (Thu,) studied this question.