Environment-dependent taste-aversion extinction: A question of stimulus novelty at conditioning

Abstract

In Experiment 1, four groups of rats were exposed to two saccharin(Sac)-lithium chloride(LiCl) pairings in a novel animal compartment. In subsequent daily extinction trials, Sac (two groups) or water (H2O) (two groups) was presented either in the same (as conditioning) or a different compartment. There was no evidence that the presence or absence of the conditioning compartment influenced the amounts of Sac or H2O drunk. Postextinction preference tests (Sac vs. H2O), performed in the conditioning compartment, showed a compartment-dependent extinction effect: There was a significantly stronger aversion in the group drinking Sac during extinction in a different (from conditioning) compartment than in the group drinking Sac in the conditioning compartment. In Experiment 2, four groups were given two Sac-LiCl trials in a novel (2 groups) or a familiar (2 groups) compartment. One “novel compartment” group and one “familiar” group were offered Sac during daily Sac-aversion extinction trials in the conditioning compartment, and the remaining groups drank Sac in a different compartment. Again, intercompartment generalization of the Sac aversion was demonstrated: There was no evidence that the particular compartment present influenced the strength of aversion during extinction. Postextinction preference tests showed the previously observed compartment-dependent extinction effect only in the case of the “novel compartment” groups. Thus, in view of previously reported data, the number of conditioning trials and the novelty of the conditioning compartment were shown to be critical to compartment-dependent taste-aversion extinction.