Rats were used to examine the extent to which extinction of an acquired conditioned taste aversion retards subsequent reacquisition. A saccharin-flavored solution (sac) was paired with LiCI and then followed by C8-alone extinction trials with this flavor. A control group received a different flavor, decaffeinated-coffee (coff) , during initial conditioning and extinction. Sac was then paired with LiCIfor all rats during a second conditioning phase. Reacquisition of the aversion to sac was retarded relative to the acquisition of an aversion to sac by the control group. A similar experiment with fewer extinction trials, but still with complete loss of the initial aversion, did not obtain slow reacquisition. The results are discussed with respect to an interference view of extinction and the slowreacquisition effect.

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Using a conditioned taste aversion preparation, overshadowing of flavor-illness association was produced through the presentation of a second flavor during the interval between the fIrst flavor and illness. The modulatory effects of extinguishing the association between the second (overshadowing) flavor and illness on conditioned responding to the target flavor was investigated.In Experiment 1, we found that, following one-trial overshadowing, extinction of the overshadowing flavor had no effect on conditioned responding to the target flavor. In Experiment 2, we found a similar absence of an effect of extinction of the overshadowing stimulus in a multitrial overshadowing paradigm. Experiment 3 conflrmed the results of Experiments 1 and 2 using conditioning parameters that were designed to weaken the association between the overshadowed flavor and illness. In Experiments 4 and, 5, we used simultaneous presentation of the flavors during conditioning and obtained a weakened aversion to the overshadowed flavor when the overshadowing CS was extinguished. These findings are inconsistent with previous observations in conditioned fear preparations that suggest that extinction of the association between the overshadowing stimulus and the unconditioned stimulus attenuates overshadowing. Possible reasons for the discrepant results are discussed.

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