Elizabeth D. Capaldi

Why we eat what we eat : the psychology of eating

Ingestive Homeostasis: The Primacy of Learning - Douglas S. Ramsey, Randy J. Seeley, Robert C. Bolles, and Stephen C. Woods - Taste Aversion Learning - Glenn E. Schafe and Ilene L. Bernstein - Conditioned Food Preferences - Elizabeth D. Capaldi - The Early Development of Human Flavor Preferences - Julie A. Mennella and Gary K. Beauchamp - The Role of Experience in the Development of Childrens Eating Behavior - Leann L. Birch and Jennifer A. Fisher - Sensory Factors in Feeding - Valerie B. Duffy and Linda M. Bartoshuk - Brain Mechanisms and the Physiology of Feeding - Neil E. Rowland, Bai-Han Li, and Annie Morien - Social Influences on Food Preferences and Feeding Behaviors of Vertebrates - Bennett G. Galef, Jr. - Sociocultural Influences on Human Food Selection - Paul Rozin - Sensory-Specific Satiety: Theoretical Frameworks and Central Characteristics - Marion M. Hetherington and Barbara J. Rolls - The Behavioral Phenotype in Human Obesity - Adam Drewnowski

Taste, experience, and feeding

There has been a recent surge of work on taste, experience, and feeding. This development reflects several factors, including behavioral work on taste aversion, which has led to a concern with how positive consequences can affect taste preferences, progress in understanding the physiological basis of taste, as well as a practical concern with human obesity and how it is affected by taste and experiential factors. This volume has been divided into six parts, each dealing with a different aspect of taste and feeding. The first part of this volume deals with the current perspective of and approach to feeding used by most researchers. Taste perception is the focus of the second part. The third part of this volume deals with the genetic and the developmental aspects of taste and feeding. Learning and feeding are the concerns of chapters 10, 11, 12, and 13 in part four. Part five concerns work done with taste preferences, food consumption, and human obesity.

Conditioned Food Preferences

Publisher Summary This chapter explores that humans have receptors for four basic tastes: salt, sour, bitter, and sweet. Initial affective reactions to these four tastes appear to be genetically mediated. Initial reaction to the four basic tastes appears to be genetically mediated, in omnivores such as rats and humans most food preferences are produced by experience. This may seem anti-intuitive because individuals seem to have strong preferences upon initial contact with food. In theory at least, many of these preferences can be accounted for in terms of differences in individual experiences with foods. Individuals differ widely in their experiences with foods, and laboratory research has shown that different experiences with foods can produce long-lasting conditioned food preferences. By the age of 6 months, large individual differences in preference for sweet develop shows differences that can be traced to experience. Some infants are given sugar water as a pacifier, while others are not. When tested at 6 months of age, infants who have been given sugar water show a greater preference for sweet than those who have not had this experience. Differences in sweet preference between those given sweetened water and those not given sweetened water are still present when the children are 2 years old, even if sweetened water was discontinued. The chapter also discusses that food preferences are affected by learning the consequences associated with ingestion of foods and by associations formed between foods that are experienced together. It aims to review the data from laboratory showing increases in preference for flavors paired with beneficial consequences.

Conditioned Flavor Preferences Based on Delayed Caloric Consequences

In four experiments we showed that rats prefer a flavor associated with a delayed edible consequence if the delayed consequence contains calories; the greater the number of calories, the greater the preference. We obtained conditioned preferences with delayed consequences of dextrose plus quinine, 8% polycose, 8% sucrose, 10 g of high fat mash, and 14 g of lab chow. No conditioned preferences were obtained with delayed consequences of saccharin, 10 g of low fat mash, 1% polycose, or 1% sucrose. Thus, it seems that flavor preferences based on delayed caloric consequences occur only if there are appreciable calories in the consequence.

Decreasing dislike for sour and bitter in children and adults.

Strategies for preference conditioning were investigated in children (Experiment 1) and adults (Experiment 2). In Experiment 1, subjects were 49 children, between the ages of 2 and 5 years old. The results showed that initially mixing grapefruit juice with the sweet taste of sucrose increased liking for the sour taste of grapefruit juice (without the added sucrose) and that this increased liking persisted weeks later. In Experiment 2, subjects were 62 undergraduates with a median age of 18 years. Consistent with Experiment 1, the results showed that initially mixing broccoli or cauliflower with the sweet taste of sugar increased liking for the bitter taste of these vegetables. The results are discussed in terms of decreasing dislike for fruits and vegetables.

Conditioned flavor preferences based on hunger level during original flavor exposure

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 low-deprivation 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.

Effects of food deprivation on learning and expression of flavor preferences conditioned by saccharin or sucrose

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 of sweetness 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.

Taste preferences as a function of food deprivation during original taste exposure

It has been reported previously that rats prefer a flavor they consumed under high deprivation to a flavor they consumed under low deprivation (Revusky, 1967). Here it was found that this preference occurs only if nutritive solutions are used and the flavors are given preceding and following eating. If flavors are given separately from the daily feeding, rats prefer the flavor given under low deprivation, whether or not a nutritive solution is used (Experiment 3). If flavors are given before and after the daily feeding, rats prefer the flavor they had under high deprivation (before feeding) more if sucrose solutions are used than if saccharin solutions are used and more on a high-deprivation test than on a low-deprivation test (Experiments 1 and 2). It was concluded that the “incentive value” of consumption is not necessarily higher under high deprivation than under low deprivation. The preference for the low-deprivation flavor obtained here may reflect a greater proportional rewarding effect of consumption under low deprivation or may reflect an aversion to the flavor consumed under high deprivation. Perhaps a small taste of flavor under high deprivation initiates responses of digestion that are unsatisfied and thus aversive, and the more so the higher the deprivation level.

Flavor-nutrient learning independent of flavor-taste learning with college students.

Flavor preference learning is mediated by associations with other liked tastes (flavor-taste learning) or calories (flavor-nutrient learning). The present study asked whether flavor-nutrient learning could be exhibited independent of flavor-taste learning in humans (as has been shown in animals). Subjects were 24 undergraduates with a mean age of 19 years. Half the subjects received the bitter-tasting cream cheese crackers with high fat cream cheese, half with low fat cream cheeses. Half the cream cheeses were flavored orange, half banana in each group. Results showed that subjects who had high fat flavored cream cheese rated the flavor more pleasant in plain crackers than subjects who had the flavor in low fat cream cheese (flavor-nutrient learning), although all cream cheese crackers were bitter tasting in training (flavor-taste learning).

Isocaloric meal and snack foods differentially affect eating behavior

The present study tested whether foods categorized as meals reduce subsequent intake more than isocaloric foods categorized as snacks. The study was repeated three times with variations. In each variation we manipulated whether subjects received meal or snack foods in an isocaloric load. In Variation 1, subjects consumed less following a load of meal foods than snacks. Variation 2 found this effect to be short-term, affecting food choice 20 min following a load but not 3 h later. Variation 3 demonstrated: (1) this effect occurs independent of the effects of the weights of foods, and (2) this effect varies specifically with subject perceptions of foods (i.e. whether they are part of a meal or snack). These results are discussed in terms of how cognitive representations of preload foods can influence subsequent consumption.