Interactions between conditioned and unconditioned flavor preferences

Five experiments investigated how rats' conditioned preferences or aversions for aqueous odors paired with sucrose or salt are affected by their unconditioned response to those tastes. Rats preferred an odor paired with 30% sucrose over an odor paired with 5% sucrose when both were presented in 5% sucrose, but they showed no preference or, if thirsty, showed the reverse preference, when the odors were presented in 30% sucrose. These changes in conditioned preference corresponded to changes in the rats' unconditioned preference for the accompanying sucrose solution. Rats' conditioned aversions for odors paired with salt showed a similar dependence on their reaction to the accompanying salt solution. The results were interpreted as showing that conditioned and unconditioned flavor preferences combine additively, as if mediated by the same sensory representation.