In five experiments, rats' preference for a flavor was greater if the flavor had previously been consumed under low rather than high deprivation. This preference was conditioned in as few as three flavor-deprivation pairings (Experiment 1), and persisted through 28 test days, half under each deprivation level (Experiment 2). Rats never preferred the flavor associated with high deprivation even when calories were increased by giving 40 ml of 8% sucrose or when caloric density was increased to the equivalent of 20% sucrose. The preference for the lowdeprivation flavor was greater when saccharin solutions were used rather than sucrose solutions, but the preference did emerge when sucrose solutions were used as testing proceeded and when a lower concentration of sucrose was used. We suggest that these preferences may be a result of flavor-taste associations rather than associations between flavors and postingestive consequences, and that the taste of the solutions under low deprivation is preferred to the taste under high deprivation.We recently found that rats' preference for a flavor was greater if they had previously consumed it under low rather than high hunger when flavors were given separately from the daily feeding (Capaldi & Myers, 1982). Given the widespread assumption that the incentive value of food increases with increased hunger (e.g., Kurtz & Jarka, Revusky, 1967), this finding is surprising. Our aim in the first two of the present experiments was to establish the reliability of this effect and the range of conditions under which it occurs. Experiment 1 looked for the effect with minimal training, and Experiment 2 measured the persistence of the effect. EXPERIMENT 1Experiment 1 used 6 training days. In all our previous experiments, we have used 20 training days. However, taste aversions based on illness can be conditioned rapidly (Logue, 1979), so it was of interest to determine if taste preferences! based on hunger level were also learned rapidly. MetbodSubjects. The subjects were 24 male albino rats, 174 days old at the beginning of the experiment. They were 78 days old on arrival from the Holtzman Co., Madison, Wisconsin, and had been employed in a straight alley instrumental learning experiment in which they had received 14 g of food per day for 69 days. New groups were formed by evenly redistributing the rats from the old groups.Reprints can be obtained from Elizabeth D. Capaldi, Department of Psychological Sciences, Purdue University, West Lafayette, Indiana 47907. 107Materials. Flavored solutions were presented in 50-ml Nalgene centrifuge tubes with rubber stoppers and metal spouts. Flavor cues consisted of 111fo cinnamon (211fo imitation cinnamon flavoring mixed with 100llfo ethanol) or 111fo wintergreen (211fo imitation wintergreen flavoring mixed with IOOllfo ethanol) dissolved in a saccharin solution with water (.15I1fo saccharin) or a sucrosewater solution (811fo sucrose).Procedure. All training and testing occurred in the rats' home cages. Ad-lib water was available throughout the experime...

his chapter reviews the various ways animals, including humans, form T preferences for foods through experience and how these preferences might be changed. As will be seen, in omnivores such as rats and people, most food preferences are produced by experience. This fact is counterintuitive because individuals appear to have such pronounced likes and dislikes on their first encounter with a food; yet few of these preferences are built in. Exposure to food with no consequences increases liking; however, if there are consequences of consuming food (getting sick, feeling full), these consequences determine preference. The taste and other sensory qualities of food also contribute to preference. The taste of food produces liking and disliking that appear to be genetically mediated, whereas, the other sensory characteristics of food (odor, temperature, texture, appearance) appear to produce their effect through learning.Most of the work in this area has been done with animals because their experience can be precisely controlled. The principles derived from the animal work have been validated with humans, however, and human experiments are also described in this chapter.There are four known ways to increase preference for a food: mere exposure, the medicine effect, flavor-j7avor learning, and flavor-n u trien t learning. In mere exposure, consuming a food repeatedly increases preference for that food. As mentioned in chapter 4, human infants prefer the odor and taste of foods consumed by their mothers. This process continues throughout life and is believed to have a biological basis. Because foods that are 53

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In four experiments, food deprivation was varied during conditioning and testing of conditioning of flavor preferences by sweeteners. Conditioned preferences for a flavor associated with a more concentrated solution were enhanced by increased deprivation in training whether sucrose or saccharin was used when rats consumed solutions freely during training. When consumption of solutions was controlled and higher deprivation levels were used, preference for the higher concentration of sucrose was still enhanced by increased deprivation in training, but this did not occur with saccharin. We suggest that deprivation may enhance the reinforcing value ofsweetness only when calories increase along with sweetness. We also suggest that deprivation can enhance flavor preference learning by increasing consumption and thereby increasing exposure to ' the flavored solutions.

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