Superconditioning and overshadowing

Abstract

Conditioned lick suppression by water-deprived rats was used to investigate the phenomenon of superconditioning. In Experiment 1, animals received explicitly unpaired conditioned inhibition training with CS A or CS B and a footshock US. Both groups then received pairings of a CS A-light compound with shock. In testing, animals for which CS A was inhibitory displayed enhanced responding to the light, relative to animals for which CS A was associatively neutral. Thus, superconditioning relative to the conventional control group was demonstrated. However, an additional control group that first received inhibitory training with CS A and then the light alone paired with shock exhibited as much suppression to the light as the superconditioning group. This control, which was omitted from previous demonstrations of superconditioning, suggests that superconditioning is merely attenuated overshadowing of the added element by CS A as a result of prior inhibitory training with CS A. In Experiment 2, superconditioning was not obtained when partial reinforcement of CS A occurred during negative contingency training, despite the fact that in prior research the identically trained CS A had passed both summation and retardation tests for inhibition. In Experiment 3, exposure to CS A alone (i.e., latent inhibition treatment) sufficed to produce a superconditioning-like effect with respect to the light when the CS A-light compound was later paired with shock. In Experiment 4, conditioned inhibition and latent inhibition treatments of CS A were found to yield equivalent superconditioning-like effects with respect to the added element. Collectively, these studies suggest that superconditioning arises from a reduction in overshadowing and a comparable effect can be obtained through any initial treatment that diminishes the associability of the overshadowing CS.