Effects of interference stimuli on the acquisition of learned aversions to foods in the rat.

A learned food aversion paradigm was developed to investigate characteristics of aversion learning likely to be involved in nutrient selection. The development of aversions to a relatively familiar, complete food was examined in rats with continuous access to that food. Learned food aversions were observed which were specific to the particular diet present during a sequence of toxic drug injections. In subsequent studies, novel liquids and solids were introduced in association with drug treatment to examine their effectiveness as interference stimuli. Flavored solutions, which have previously been reported to interfere with conditioned taste aversions, had little or no effect on learned aversions to the diet. This lack of interference by novel flavored liquids was coupled with significant conditioned aversions to the novel liquids themselves. Novel flavored solutions were contrasted with novel foods, which were extremely effective as interference stimuli in this paradigm. Possible bases for the observed differences in interference effects of foods and drinks are examined.