The effects of stimulus preexposure on taste-mediated environmental conditioning: Potentiation and overshadowing

Abstract

On four occasions, Holtzman rats drank saccharin in a distinctive environment prior to lithium-induced toxicosis. Preconditioning exposure to saccharin either in the home cage or in the distinctive environment interfered significantly with the establishment of an environmental aversion. Animals preexposed to the experimental environment, however, showed environmental aversions substantially stronger than those in animals preexposed to saccharin and only slightly higher than those with no preexposure to either the taste or the environment. Subsequent saccharin tests revealed significantly stronger aversions in the group that received environmental preexposure than in any of the other groups. This pattern of outcomes demonstrates taste-mediated potentiation of novel and familiar environmental stimuli as well as overshadowing of the taste by novel environmental stimuli. Furthermore, it indicates that previous demonstrations of taste-mediated environmental potentiation involve facilitated conditioning of the environmental stimuli and decremented conditioning of the taste stimuli. © 1986 Psychonomic Society, Inc.