The UCS preexposure effect in taste aversion learning: Tolerance and blocking are drug specific

Abstract

Following drug preexposure, rats were given taste aversion conditioning in either the preexposure environment or the home cage. For animals preexposed to LiCl, only the subjects conditioned in the preexposure environment showed the typical UCS preexposure effect, that is, an attenuated aversion, an effect consistent with a blocking interpretation of the LiCl-induced preexposure effect. On the other hand, all rats preexposed to morphine displayed attenuated aversions, independent of the preexposure and conditioning environments, an effect consistent with a pharmacological tolerance explanation of the UCS preexposure effect to morphine. The specific mechanism underlying the drug-induced attenuation appears to be drug-dependent. © 1982 Psychonomic Society, Inc.