Motivational state regulates the content of learned flavor preferences

Rats acquired a preference for an aqueous odor (almond) presented in simult aneous compound with sucrose. Separate presentations of saccharin reduced t his preference in rats with ad-lib access to food during training or at tes t, but not in rats that were hungry during both training and test. In contr ast, separate presentations of sucrose reduced the preference for the almon d irrespective of deprivation state during training and test. We interpret the results to mean that a hungry rat forms odor-taste and odor-calorie ass ociations, and its motivational state on test determines which of these ass ociations controls the preference. In contrast, a rat that is not hungry du ring training only forms an odor-taste association, and its performance on test is independent of its level of hunger.