Illness-alone exposure as a source of interference with the acquisition and retention of a taste aversion.

Abstract

Four studies were conducted to explore the effects of unpaired LiCl injections, the unconditioned stimulus (US), on the acquisition and retention of a taste aversion. Rats were preexposed to a US; for 1 group the US was paired with a distinctive taste, whereas for a 2nd group it was not. Following this preparation, both groups received the US paired with a novel taste. Only the US-alone group showed a retardation of subsequent taste-aversion conditioning. Exposure to LiCl without a specific gustatory cue will interfere with the avoidance of a specific taste, regardless of whether the US experience occurs before or after a single taste-LiCl pairing. Following sucrose-LiCl pairings, LiCl-alone exposures retroactively interfered with the retention of the prior aversion to sucrose, with the level of post-US interference becoming an increasing function of the number of US-alone experiences. The association of sucrose with LiCl did not interfere with the development of an almond aversion, whereas LiCl-alone exposures following the acquisition of a sucrose aversion proactively interfered with the development of a 2nd taste aversion (almond). A physiological explanation does not adequately account for the results. The results are discussed within the framework of alternative associative models.