Simultaneous Overshadowing and Potentiation of Taste and Contextual Cues by a Second Taste in Toxicosis Conditioning

Three experiments examined the effect of sucrose consumption in a novel context on the conditioning of an aversion to that context. In Experiment 1, rats were injected with LiCl after drinking either sucrose (Group SUC-LI) or water (Group WAT-LI) in a novel context (context 2). An unpoisoned control group consumed water in context 2 and was injected with isotonic saline solution (Group WAT-SAL). On test, when presented with saline in context 2, Group WAT-LI consumed less than Group WAT-SAL, suggesting that a conditioned aversion to context 2 developed in Group WAT-LI. Group SUC-LI consumed less than Group WAT-LI, suggesting that the sucrose had potentiated a context aversion in Group SUC-LI. Experiment 2 was similar to Experiment 1, except that rats drank a novel vinegar solution in context 1 before entering context 2 for conditioning. On test, Group SUC-LI drank more vinegar in context 1, and less saline in context 2, than Group WAT-LI, suggesting that sucrose had simultaneously overshadowed vinegar and potentiated an aversion to context 2. Experiments 3a and 3b confirmed that the results of Experiment 2 were due to potentiation rather than generalization of a sucrose aversion to familiar saline. © 1996 Academic Press, Inc.