HEDONIC HUNGER AND SELF-CONTROL: THE IMPACT OF PALATABILITY, POWER OF FOOD AND DIETARY RESTRAINT ON SELF-CONTROL DEPLETION. Kathleen M.

Transcription

1 HEDONIC HUNGER AND SELF-CONTROL: THE IMPACT OF PALATABILITY, POWER OF FOOD AND DIETARY RESTRAINT ON SELF-CONTROL DEPLETION Kathleen M. Young A Dissertation Submitted to the Graduate College of Bowling Green State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY August 2011 Committee: Robert A. Carels, Adviser Susan K. Huss Graduate Faculty Representative William H. O Brien Michael J. Zickar

2 ii ABSTRACT Robert A. Carels, Advisor Individuals utilize self-regulatory resources daily in countless circumstances. The depletion of self-regulatory resources may impair an individual s ability to resist eating tempting (i.e., palatable) foods in a food-rich environment. Certain people may be particularly susceptible to the presence of palatable foods in their eating environment. These individuals are believed to possess a greater propensity to the experience of hedonic hunger. Hedonic, or psychological, hunger represents a condition in which individuals feel a desire to consume palatable foods, even in the absence of physiological hunger. Dietary restraint and power of food represent two individual characteristics in which greater susceptibility to hedonic hunger appears to be a central characteristic. The need to resist hedonic hunger during exposure to palatable foods may result in depletion of self-control resources and depletion in the performance of subsequent tasks involving self-control, particularly among individuals high in the power of food and/or dietary restraint. The present study examined the contributions of dietary restraint and power of food to self-control depletion following a task intended to elicit or not elicit hedonic hunger. It was hypothesized that power of food and dietary restraint would be related to greater self-control depletion following the elicitation of hedonic hunger, and that depletion would be even greater for those who were higher in both power of food and dietary restraint. Participants were 105 undergraduate students recruited from undergraduate psychology classes. Results indicated that power of food was unrelated to self-control depletion, regardless of the elicitation of hedonic hunger. Dietary restraint was found to have an unanticipated relationship with self-control

3 depletion, with individuals higher in dietary restraint demonstrating less self-control depletion across hedonic hunger conditions. A three-way interaction between power of food, dietary restraint, and hedonic hunger emerged, but the results did not support the hypothesized outcome. Implications of the study s findings are discussed, as well as suggested directions for future research related to power of food, dietary restraint, hedonic hunger, and self-control.

4 ACKNOWLEDGMENTS I would like to thank my adviser, Robert Carels, for all of his help and support of me throughout my time in graduate school, and especially for guiding me through the process of completing my dissertation. I would also like to thank my committee members, William O Brien, Michael Zickar, and Susan Huss, for their time, consideration, and suggestions. Finally, I would like to thank Andrea Hulme, Claire Hoover, and Emily Myers for their help in collecting the data that was utilized in this project.

5 TABLE OF CONTENTS Page INTRODUCTION... 1 Self-Control... 4 Studies demonstrating self-control strength Hedonic Hunger... 9 Power of Food Dietary Restraint Dietary Restraint, Power of Food, and Hedonic Hunger The Present Study METHOD Participants Study Design Measures Demographic questionnaire Mood Social desirability Self-control demands Self-control strength/depletion Dietary restraint Power of food Hedonic value of food (palatability) Craving Experimenters

6 Procedure Food exposure task (adapted from Baumeister et al., 1998) Self-control task (adapted from Baumeister et al., 1998) Data Analysis RESULTS Descriptive Statistics Hedonic Hunger, Power of Food, and Self-Control Depletion Control variables Hedonic hunger Power of food Interaction between power of food and hedonic hunger Hedonic Hunger, Dietary restraint, and Self-Control Depletion Control variables Dietary restraint Power of food Interaction between dietary restraint and hedonic hunger Hedonic Hunger, Power of Food, Dietary Restraint, and Self-Control Depletion Control variables Hedonic hunger Power of food and dietary restraint Two-way interactions for power of food, dietary restraint, and hedonic hunger... 32

7 Three-way interaction between power of food, dietary restraint, and hedonic hunger Post-Hoc Analyses Hedonic hunger, power of food, dietary restraint, and self-control depletion by gender Hedonic hunger, power of food, gender, and self-control depletion Hedonic hunger, dietary restraint, gender, and self-control depletion Hedonic hunger, craving, and self-control depletion Hedonic hunger, power of food, craving, and self-control depletion Hedonic hunger, dietary restraint, craving, and self-control depletion Power of food, dietary restraint, and craving DISCUSSION Summary Post-Hoc Analyses Integration of Findings with Past Literature Power of food, hedonic hunger, and self-control depletion Dietary restraint, hedonic hunger, and self-control depletion Power of food, dietary restraint, hedonic hunger, and self-control depletion Limitations

8 Implications Future Directions REFERENCES APPENDIX A. DEMOGRAPHIC QUESTIONNAIRE APPENDIX B. POSITIVE AND NEGATIVE AFFECT SCALE (PANAS) APPENDIX C. MARLOWE-CROWNE SOCIAL DESIRABILITY SCALE APPENDIX D. SELF CONTROL DEMANDS ASSESSMENT APPENDIX E. ANAGRAMS APPENDIX F. RESTRAINT SCALE APPENDIX G. POWER OF FOOD SCALE APPENDIX H. FOOD PALATABILITY SCALE APPENDIX I. FOOD CRAVING QUESTIONNAIRE-STATE (FCQ-S) APPENDIX J. SUMMARY OF HEIRARCHICAL REGRESSION ANALYSIS FOR POWER OF FOOD, DIETARY RESTRAINT, AND HEDONIC HUNGER PREDICTING SELF-CONTROL DEPLETION USING UNTRANSFORMED DATA (N = 112) APPENDIX K. INTERACTION PLOTS FOR THE INTERACTION OF POWER OF FOOD, DIETARY RESTRAINT, AND HEDONIC HUNGER USING THE UNTRANSFORMED DATA APPENDIX L. PARTICIPANT CONSENT FORM. 72

9 LIST OF TABLES Table Page 1 Correlation Matrix among Primary Study Measures (N = 105) Demographic Characteristics Summary of Hierarchical Regression Analysis for Power of Food and Hedonic Hunger Predicting Self-Control Depletion (N = 105) Summary of Hierarchical Regression Analysis for Dietary Restraint and Hedonic Hunger Predicting Self-Control Depletion (N = 105) Summary of Hierarchical Regression Analysis for Power of Food, Dietary Restraint, and Hedonic Hunger Predicting Self-Control Depletion (N = 105) Summary of Hierarchical Regression Analysis for Power of Food, Dietary Restraint, and Hedonic Hunger Predicting Self-Control Depletion for Men (N = 30) Summary of Hierarchical Regression Analysis for Power of Food, Dietary Restraint, and Hedonic Hunger Predicting Self-Control Depletion for Women (N = 75) Summary of Hierarchical Regression Analysis for Power of Food, Gender, and Hedonic Hunger Predicting Self-Control Depletion (N = 105) Summary of Hierarchical Regression Analysis for Dietary Restraint, Gender, and Hedonic Hunger Predicting Self-Control Depletion (N = 105) Summary of Hierarchical Multiple Regression Analysis for

10 Craving and Hedonic Hunger Predicting Self-Control Depletion (N = 105) Summary of Hierarchical Multiple Regression Analysis for Craving, Power of Food, and Hedonic Hunger Predicting Self-Control Depletion (N = 105) Summary of Hierarchical Multiple Regression Analysis for Craving, Dietary Restraint and Hedonic Hunger Predicting Self-Control Depletion (N = 105) Summary of Hierarchical Multiple Regression Analysis for Power of Food and Dietary Restraint Predicting Craving (N = 105)

11 LIST OF FIGURES Figure Page 1 Three-way interaction between dietary restraint, power of food, and hedonic hunger. Three-way interaction significant at p < Interaction between gender and power of food. Interaction significant at p < Three-way interaction between dietary restraint, craving, and hedonic hunger. Three-way interaction significant at p < Three-way interaction between dietary restraint, power of food, and hedonic hunger. Three-way interaction significant at p <

12 Hedonic Hunger 1 INTRODUCTION The importance of human self-regulation (i.e., self-control) in health and wellness cannot be overstated. Self-regulation is exercised in some capacity in countless everyday circumstances. For example, inhibiting impulses, actively making choices, persisting in the face of failure, and regulating emotions all depend on successful self-regulation (Schmeichel & Baumeister, 2004). Many health-related choices, such as resisting the temptation to smoke, or going to the gym at the end of a long day, would not occur without the use of self-regulatory resources. For individuals who are trying to lose or maintain weight, successful self-regulation is likely to contribute heavily to their success. In fact, many dieters cite the failure of selfregulation as a barrier to attaining their weight-related goals (Ziebland, Thorogood, Yudkin, Jones, & Coulter, 1998; Johnson, Corrigan, Dubbert, & Gramling, 1990). Considering that approximately 39% of women and 21% of men state that they are trying to lose weight (Hill, 2002), it is important to understand what leads to the successful self-regulation of eating habits. Further, certain individuals, often described as restrainers, appear to be chronic dieters regardless of their size (Herman & Polivy, 1980; Lowe, 1993). Chronic self-regulation of eating behaviors is a hallmark of these individuals. These individuals are also characterized by a preoccupation with forbidden foods and weight, as well as fluctuations between strict dietary restriction and disinhibited eating behavior (Herman & Polivy, 1980; Herman & Polivy, 1984). Finally, the experience of utilizing self-control to resist the impulse to eat a highly palatable food is a familiar situation for most individuals. Thus, self-regulation of eating behaviors is a common experience across individuals with various eating and dieting goals. The growing rates of obesity suggest that the self-regulation of food intake is being undermined more and more frequently. In an attempt to explain the growing number of unsuccessful and chronic dieters (i.e., rising obesity rates strongly suggest that dieting attempts

13 Hedonic Hunger 2 are unsuccessful), weight loss and nutrition experts propose that recent changes to the food and physical activity environments are undermining people s attempts to use self-control to diminish consumption of large portions and highly palatable food (Brownell & Horgen, 2004). For example, in recent decades, the variety of palatable snacks has multiplied (Hodgen, 2003), portion sizes of high-caloric foods have increased (Young & Nestle, 2003; Young & Nestle, 2002), and opportunities to eat generous portions of appetizing foods have grown (Farmer, 2005). These changes in food availability, variety, and portion size have implications for both eating behavior and self-control. Research shows that without being aware of it, individuals consume more when food is visible and conveniently located (Painter, Wansink, & Hieggelke, 2002), when there is food variety (Rolls, Rowe, Rolls, Kingston, Megson, & Gunary, 1981), and when food portions are larger (Wansink & Kim, 2005). In fact, people make on average over 200 food-related decisions each day, to most of which they are oblivious (Wansink & Sobel, 2007). In today s obesogenic environment, to avoid overconsumption, individuals must constantly use self-regulation to inhibit their food consumption. Unfortunately, however, research indicates that self-control is a limited resource, and that using self-control appears to have a cost. For example, research has shown that the use of selfcontrol in one domain diminishes self-control resources for subsequent tasks requiring selfcontrol (Schmeichel, Vohs, & Baumeister, 2003; Baumeister, Bratslavsky, Muraven, and Tice; 1998). Therefore, if an individual needs to use a considerable amount of self-control to resist overeating, s/he will have less self-control available for other tasks (including future food-related decisions). For example, it has been shown that when individuals are physiologically hungry, resisting palatable food results in self-control depletion for subsequent tasts (Stucke & Baumeister, 2006).

14 Hedonic Hunger 3 Although physiological hunger depletes self-control resources while resisting food consumption, it is unlikely that physiological hunger is the only food-related condition that depletes self-control. Just as research has identified individual differences in self-control strength, namely trait self-control (Muraven, Collins, Shiffman, & Paty, 2005), there appears to be individual differences in the experience of psychological hunger, commonly described as hedonic hunger. Hedonic hunger represents thoughts, feelings, and urges about food in the absence of any short- or long-term energy deficit [that] may or may not be prompted by exposure to food-related cues, but by definition do not occur in response to prolonged food deprivation (Lowe & Butryn, 2007, p. 432). Resisting the consumption of palatable foods, while experiencing hedonic hunger, is another condition that is likely to deplete self-control resources. Although limited, research has begun to suggest that some individuals may be particularly vulnerable to experiencing hedonic hunger. It appears that certain individuals have a tendency toward preoccupation with palatable foods, even when they are not experiencing an energy deficit (Lowe et al., 2008). Lowe and Butryn (2007) suggest that individuals who exhibit a greater tendency to be preoccupied with food, or appear to be susceptible to the power of food, may be more likely to experience bouts of hedonic hunger, especially when exposed to palatable foods. For individuals more susceptible to the power of food, resisting palatable foods may require a greater amount of self-control than for those lower in the power of food. An additional factor that might predispose someone to experience greater self-control depletion in response to palatable food, even in the absence of physiological hunger, is level of dietary restraint. As indicated earlier, restrained eaters have been defined as chronic dieters (Herman & Polivy, 1980), or individuals who have experienced frequent and repeated cycles of dieting and overeating (Lowe, 1993). This chronic approach-avoidance relationship with food is likely to require the individual who is high in dietary restraint to experience frequent bouts of

15 Hedonic Hunger 4 food-related self-control (Lowe & Butryn, 2007). In fact, research suggests that individuals high in dietary restraint exhibit self-control depletion when they are physiologically hungry and resisting palatable foods (Vohs & Heatherton, 2000). However, the unique contribution of hedonic hunger in the self-control depletion of restrainers is still unknown. The above findings on dietary restraint and susceptibility to the power of food suggest that the amount of self-control depletion that occurs as a result of exposure to palatable foods is influenced by a combination of environmental and individual factors. The purpose of the proposed study is to examine two individual difference factors, power of food (Lowe et al., 2008) and dietary restraint (Herman & Polivy, 1980), plausibly related to self-control depletion in the presence of palatable foods (Lowe & Butryn, 2007), while in the absence of physiological hunger. In the following paper, first, research demonstrating the nature of self-control is reviewed. Second, the concepts of hedonic hunger, power of food, and dietary restraint are discussed, as well as the possible relationships among the three characteristics. Third, the hypotheses and method of the present study are presented. Fourth, the results of the present study are presented. Finally, the findings of the present study are discussed, as well as implications, limitations, and directions for future research. Self-Control Muraven and Baumeister (2000) define self-control as the exertion of control over the self by the self (p. 247). Thus, self-control happens when a person tries to change the way he or she would normally think, feel, or behave (Muraven & Baumeister, 2000). During the exertion of self-control, responses are regulated in an active way to move the individual closer to desired states, such as personal goals, plans or standards (Schmeichel & Baumeister, 2004; Heatherton & Baumeister, 1996).

16 Hedonic Hunger 5 Behaviors utilizing self-control are distinguished from those relying on automatic processes and behavioral sequences (Bargh & Chartrand, 1999). However, behaviors initially requiring self-control may become automatized through repetition, diminishing the need for selfcontrol. These automatic goal-directed behavioral sequences ultimately allow the individual to perform behaviors more efficiently while preserving self-regulatory strength (Bargh, 1994). Nonetheless, self-control is important because it allows the individual to move toward desired long-term goals in the face of immediate challenges. When self-control fails, individuals may fail to inhibit impulses and behavior, which inevitably may result in undesirable consequences such as drug addiction, debt, weight gain, and damaged relationships with others (Baumeister, Heatherton, & Tice, 1994). Because of the negative consequences of self-control failure, it is important to better understand the nature of self-control and self-control failure. Baumeister, Heatherton, and Tice (1994) have proposed a self-control strength model to describe the nature of the self-control process in making decisions, initiating and interrupting behavior, and exerting control. Several assumptions underlie the self-control strength model (also referred to as self-regulatory strength and ego strength). First, self-control strength is necessary for executive functions such as making decisions, initiating and interrupting behavior, and exerting control (Baumeister, 1998). Second, self-control strength is limited in its capacity (Muraven & Baumeister, 2000). Third, all self-control functions operate from the same resource, such that self-control resources are not divided into different spheres (Muraven & Baumeister, 2000). This means that utilization of self-control in one domain decreases the amount of available self-control in other domains. Fourth, success or failure of self-control depends on an individual s level of self-control strength, among other factors (Muraven & Baumeister, 2000). This means that people with more self-control strength should be more likely to reach a goal that requires self-control than those

17 Hedonic Hunger 6 with lower self-control strength. Therefore, self-control strength depletion impacts subsequent tasks that require more self-control than those that require less self-control (e.g., pre-existing self-control strength depletion should impact the likelihood of eating at an undesirable time more for restrained eaters than for unrestrained eaters, because restrained eaters should need to exert self-control to resist food, while unrestrained eaters should not need to exert self-control to resist food). Fifth, self-control strength is expended during acts of self-control, which means that less self-control strength is available for subsequent self-control acts (Muraven & Baumeister, 2000). Thus, it is like a muscle in that it becomes fatigued after use and is less able to function. However, after periods of rest (i.e., times when self-control is not being used), the resource of self-control can be replenished. Finally, like a muscle, self-control strength capacity can be increased over time through the utilization/exercise of self-control (Muraven & Baumeister, 2000). Although the use of self-control decreases the capacity of self-control strength over the short-term, it may increase its capacity over the long-term. Studies demonstrating self-control strength. Multiple studies have been conducted to test the above assumptions regarding self-control. An experiment by Baumeister, Bratslavsky, Muraven, and Tice (1998) demonstrated the nature of self-control as a limited resource across multiple spheres of self-control. In this experiment, participants were asked to sit in a room where chocolate chip cookies had just been baked and displays of chocolate chip cookies and radishes were sitting on tables. The participants were asked to not eat chocolate chip cookies or radishes for the next 24 hours, other than during the experiment. Participants then were asked to sample either the radishes or cookies for five minutes, and were told to eat only the food they were assigned to eat. After a 15-minute period where participants filled out questionnaires, participants were asked to complete tracing tasks that were impossible to solve. Persistence in

18 Hedonic Hunger 7 the task which involves self-control was measured by the amount of time participants worked on the tasks before giving up. Individuals who were assigned to the radish condition quit the task significantly sooner than those in the cookie task and the control condition (i.e., individuals who worked on the puzzles without participating in a food condition). Baumeister et al. (1998) argued that their results indicated that utilizing self-control in one area (refraining from eating a tempting food) impaired self-control strength for a subsequent, unrelated task (persisting at unsolvable puzzles). Research has continued to support the construct of self-control strength as a limited resource that is used through multiple areas of function. Stucke and Baumeister (2006) found that individuals who were physiologically hungry and resisted the urge to eat a tempting food, as well as individuals who were asked to concentrate and regulate their emotions and movement during a film, were more likely to respond aggressively to insult than individuals who were not required to perform these tasks, suggesting that inhibiting aggression also relies on the same resource of self-control strength. Another group of studies found that individuals asked to regulate their attention or emotion subsequently performed more poorly on tasks of reading comprehension, logic, and reasoning (Schmeichel, Vohs, & Baumeister, 2003, Experiments 1, 2, and 3). However, self-regulation did not influence a test of general knowledge, suggesting that self-regulation primarily plays a role in intellectual activities requiring more complex thinking rather than recalling information. These studies extend the understanding of the breadth of functions that utilize self-control resources, further supporting the assumption that self-control strength encompasses a broad range of executive functions. Eating behavior and self-control have been examined in restrained eaters. Three experiments were conducted to determine the possible self-control consequences of dietary restraint (Vohs & Heatherton, 2000, Experiments 1, 2, and 3). In the first study with restrained

19 Hedonic Hunger 8 and unrestrained eaters, restrained eaters who faced high temptation (i.e., watching a movie sitting very close to tempting snacks) ate more ice cream presented to them in a subsequent tastetesting task than restrained eaters who faced low temptation (i.e., watching a movie sitting across the room from tempting snacks). However, they only ate more ice cream if they had free (i.e., told to help themselves to enticing snacks), rather than constrained (i.e., told they were off limits by the experimenter) access to the snacks during the movie. There was no difference in the amount of ice cream consumed in unrestrained eaters, either for temptation or for availability. The researchers determined that restrained eaters were more likely to eat in tempting situations in which they had to use self-control. Additionally, they determined that individuals who were told not to touch the snacks felt like the decision was made by the experimenter and therefore did not require self-control to abstain from the snacks, allowing them to have more self-control strength available for restraint while testing the ice cream. Further, they suggested that unrestrained eaters did not show differences in self-control depletion because they were not dieting and did not need to use self-control resources to resist temptation. Although hunger was not assessed in the study, participants were instructed not to eat before the experiment and were likely experiencing physiological hunger. Thus, the contribution of hedonic hunger to self-control depletion cannot be determined. In the second experiment by Vohs and Heatherton (2000), restrained eaters who were put into a high temptation (food directly next to the participant) situation prior to a puzzle solving task persisted at the puzzles for a shorter amount of time than those who were put into a low temptation (food across the room) situation. These results indicate that, in restrained eaters, selfcontrol over food affects self-control in other domains. Yet again, however, physiological hunger cannot be ruled out as the cause of self-control depletion in this study. In the third experiment, restrained eaters who were asked to suppress their emotions when watching a movie ate more

20 Hedonic Hunger 9 during a later task than those who were able to show their emotions (Vohs & Heatherton, 2000). These findings indicate that exerting self-control in one domain can impair self-control of eating in restrained eaters. In these experiments, participants were asked not to eat before the experiment; therefore, physiological hunger may have contributed to participants self-control depletion. The possible contribution of hedonic hunger to self-control depletion in restrained eaters is unknown. In summary, self-control strength appears to be a resource that is limited in capacity and from which all self-control functions operate. Research has demonstrated that the use of selfcontrol in one domain decreases the amount of self-control available for tasks in other domains. Further, resisting food intake while physiologically hungry appears to deplete self-control strength. However, it is possible that resisting food consumption may deplete self-control resources even when an individual is not in a state of energy depletion (i.e., is not physiologically hungry). Research has suggested that there is a second food-related system, hedonic hunger, which is as real as, but distinct from, physiological hunger. It is possible that self-control resources are depleted when individuals resist food consumption while experiencing hedonic hunger. Hedonic Hunger As stated previously, hedonic hunger is defined as thoughts, feelings, and urges about food in the absence of any short- or long-term energy deficit [that] may or may not be prompted by exposure to food-related cues, but by definition... do not occur in response to prolonged food deprivation (i.e., homeostatic [physiological] hunger) (Lowe & Butryn, 2007, p. 432). Research has supported the presence of overlapping, yet distinct, homeostatic (arising from biological needs for food) and hedonic (arising from responsiveness to sensory properties of food) processes that influence eating behavior (Blundell & Finlayson, 2004).

21 Hedonic Hunger 10 Although hedonic hunger may occur in the absence of food-related cues, the immediate food environment is likely to play a large role in generating hedonic hunger, specifically through palatable food cues (Lowe & Butryn, 2007). Whether an individual is hungry or not, palatable foods often stimulate hedonic appetite and subsequent food choice (Yeomans, Blundell, & Leshem, 2004). Though palatability may be a consideration in homeostatic hunger, it is a necessary component of hedonic hunger (Blundell & Finlayson, 2004). Even when an individual is in a state of satiety, hedonic hunger results in desiring and/or continuing to eat in the presence of highly palatable foods (Blundell, Lawton, Cotton, & Macdiarmid, 1996). For example, after eating a filling meal at a restaurant, individuals who are shown a dessert tray may want and choose to eat dessert even when they are not physiologically hungry. Thus, living in an environment full of palatable food cues may repeatedly induce hedonic hunger throughout the day (Lowe & Butryn, 2007). It is possible that hedonic hunger is more strongly or more frequently elicited in certain individuals. One characteristic that may contribute to the experience of hedonic hunger is the susceptibility one has to the allure of highly palatable foods, also known as the power of food. Power of Food Power of food is described as an appetitive responsiveness to highly palatable food cues (Lowe & Butryn, 2007). Research indicates that there are individual differences in hedonic motivations to eat (Epstein & Leddy, 2006). An individual s degree of power of food is representative of the degree to which the palatable food environment influences that individual s thoughts, feelings and behavior (Lowe et al., 2008). When considering the impact of the environment on power of food, three levels of food proximity are considered: a) a general, widespread availability of palatable food in the environment, b) the physical presence of foods when they have not been tasted, and c) food when it has been tasted but not yet consumed (Lowe

22 Hedonic Hunger 11 et al., 2008). Thus, the availability of palatable foods at varying degrees of proximity may influence food responsiveness, eliciting hedonic hunger. While the hedonic value of food (i.e., palatability) has been found to augment physiological hunger and increase food intake (Blundell & Finlayson, 2004), the power of food construct was proposed to account for the responsiveness to palatable food cues when an individual is not in a state of energy depletion (Lowe et al., 2008). From a practical standpoint, it is difficult to ascertain the contribution of biological processes, such as energy deficit, and environmental factors, including the presence of or responsiveness to palatable food, when an individual is physiologically hungry (Lowe & Levine, 2005). Very little research has been performed examining the power of food on consumptive behaviors. However, research does indicate that the power of food may be more strongly related to overeating tendencies than it is to actual body mass index (BMI) (Cappelleri et al., 2008). This may not be surprising given the multitude of factors that contribute to an individual s eating patterns and weight status. For example, although power of food did not predict a portion-size effect when consuming a palatable meal, it did predict the amount of dessert consumed after the meal (Levitsky & Shen, 2008). Beyond eating influences, it is thought that the power of food over an individual may influence the activation of food-related thoughts, feelings, and motivations (Lowe et al., 2008). For example, the power of food over an individual was found to be related not only to the consumption of chocolate in a tempting situation, but also to the strength of chocolate cravings, the intensity of craving, and the distress associated with craving (Forman, Hoffman, McGrath, Herbert, Brandsma, & Lowe, 2007). The strength and distress associated with craving is likely to greatly impact self-regulatory resources. At this time, given the novelty of the constructs of hedonic hunger and the power of food, research has not closely examined the plausible association between power of food and the

23 Hedonic Hunger 12 experience of hedonic hunger. However, it is plausible that greater susceptibility to the power of food intensifies hedonic hunger, therefore requiring greater self-control resources when attempting to resist the consumption of palatable foods. Beyond the power of food, another individual difference characteristic that may be related to hedonic hunger and self-control depletion when resisting palatable foods is dietary restraint. Dietary Restraint Restraint theory (Herman & Polivy, 1980) and the boundary model (Herman & Polivy, 1984) introduced the concepts of dietary restraint and restrained eaters. According to the boundary model of restraint theory, restrained eaters are individuals who are unsuccessful chronic dieters (Herman & Polivy, 1984). Research suggests that restrained eaters typically think of foods as good or bad, forbidden or nonforbidden, and are typically preoccupied with forbidden foods (Francis, Steward, & Hounsell, 1997). Forbidden foods are most likely palatable foods that are high in fat and calorically dense (Francis et al., 1997). It has been suggested that restrainers typically overeat (i.e., counterregulate) when they have (or believe they have) consumed more of these high-caloric foods than they believe they should (i.e., broken their diet ). Plausibly, restrained eaters preoccupation with and resisting of forbidden foods may lead to self-control depletion, which is manifested through counterregulated eating behavior. These individuals are often identified using the Restraint Scale (RS; Herman & Polivy, 1980), a measure that assesses concern for dieting and weight fluctuations (Heatherton, Herman, Polivy, King, & McGree, 1988). While restrained eaters are individuals with a history of dieting and overeating, current identification as a restrained eater does not necessarily indicate current dieting or restraint (Lowe, 1993). Research has demonstrated that restrained eaters respond differently to palatable food cues than unrestrained eaters. In one study, restrained and unrestrained eaters were exposed to

24 Hedonic Hunger 13 one of four different food cue conditions: no cue, olfactory cue of a palatable food, cognitive cue of a palatable food, or a combination of olfactory and cognitive cues (Federoff, Polivy, & Herman, 1997). Restrained eaters ate more food following exposure to the palatable food cues than when not exposed to cues. Unrestrained eaters showed no difference in consumption between the no cue and palatable food cue conditions. Restrained eaters also reported a greater general desire to eat and greater liking and craving for the cued food (pizza) when exposed to any of the food cues, suggesting a possible susceptibility to hedonic hunger. Participants were instructed to eat two hours before taking part in the study, and they reported a moderate amount of hunger before starting the study. It is unknown if the hunger ratings assessed physiological hunger, hedonic hunger, or a combination of the two. Although hedonic hunger was not examined in this study, it is possible that the restrained eaters reactions to the palatable food cues were responses to hedonic hunger rather than homeostatic hunger. Although research has not examined the relationship between dietary restraint and hedonic hunger, studies examining perceived deprivation support a relationship between dietary restraint and a desire for food in the absence of physiological hunger. Studies by Timmerman and Gregg (2003) and Markowitz, Butryn, and Lowe (2008) found a relationship between restraint and perceived deprivation, but not between perceived and actual caloric deprivation (i.e., actual food consumption was unrelated to feelings of actual caloric deprivation). In fact, in the Markowitz et al. (2008) study, participants typically reported they had eaten as much as they wanted; therefore, their feelings of deprivation were unrelated to their level of satiety. It has been suggested that restrained eaters may feel as though they are deprived not because of physiological hunger, but because they are limiting what they are eating to counteract their susceptibility to overeat palatable foods (Markowitz et al., 2008). Taken together, these findings support a possible relationship between dietary restraint and hedonic hunger drives.

25 Hedonic Hunger 14 In summary, restrained eaters appear to respond to palatable food cues with increased subsequent craving and liking of the food, a general desire to eat, and increased food consumption. Furthermore, there seems to be a relationship between perceived, rather than actual, deprivation and dietary restraint. Given these findings, it is possible that restrained eaters who resist eating palatable food (and have a plausible susceptibility to hedonic hunger) in the absence of physiological hunger may demonstrate a pattern of self-control depletion similar to that found in restrained eaters who resist eating palatable food in the presence of physiological hunger, because hedonic hunger, rather than physiological hunger, is the driving force behind depletion (Vohs and Heatherton, 2000). However, the relationship between dietary restraint and self-control depletion in a condition designed to elicit hedonic hunger has yet to be determined. Dietary Restraint, Power of Food, and Hedonic Hunger It is possible that dietary restraint and power of food interact with or are related to each other under conditions of hedonic hunger, thus contributing to self-control depletion. It has been suggested that restrained eaters may represent a group of individuals who have a latent susceptibility to overconsume palatable food (Lowe & Butryn, 2007). The presence of palatable food, combined with cognitively absorbing, compelling, or taxing environmental contexts, may result in the manifestation of overeating of these foods (Lowe & Butryn, 2007). Therefore, restrained eaters may have greater susceptibility to the availability of palatable food, and their repeated dieting efforts may be intended to withstand the power of food while in the presence of highly palatable food to prevent weight gain (Lowe & Butryn, 2007). Thus, individuals who have a higher susceptibility to overeat (power of food) and make conscious efforts to avoid overeating in the presence of palatable food (restrained eaters) may experience more frequent instances of hedonic hunger (Lowe & Butryn, 2007), and may utilize more self-control resources to resist overeating. However, in studies that have utilized both power of food and dietary restraint

26 Hedonic Hunger 15 measures, power of food has been found to predict reports about eating behavior above and beyond the effects of dietary restraint (Lowe et al., 2008). The combined effects of power of food and dietary restraint on self-control depletion have not been examined. One possibility is that power of food is one of several components of restraint, which may be a composition of various society factors and influences related to food, eating, and body weight and image. The Present Study Hedonic hunger has been defined as thoughts, feelings and urges about palatable food in the absence of an energy deficit (Lowe & Butryn, 2007). It is thought that hedonic hunger can be elicited when palatable foods are present, and that individuals with a greater susceptibility to food cues (i.e., power of food) may experience hedonic hunger more often in the presence of palatable food (Lowe & Butryn, 2007). It has also been suggested that restrained eaters may represent a group of individuals that may have a susceptibility to overconsume palatable food (Lowe & Butryn, 2008). Research has shown that restrained eaters who have resisted eating in the presence of palatable food have shown more subsequent self-control depletion (Vohs & Heatherton, 2000). The purpose of the present study was to examine how the exposure to a palatable versus an unpalatable food, a tendency toward preoccupation with food, as measured by the Power of Food Scale (PFS), and dietary restraint, as measured by the Restraint Scale (RS), influence performance on a subsequent self-control task, indicating self-control depletion. Based on the definition of hedonic hunger, two requirements for the study of hedonic hunger are that a) participants are not in a state of energy depletion, and b) a highly palatable food stimulus is introduced in the experimental context (Lowe & Butryn, 2007). In this study, participants who were not in a state of energy depletion were exposed to either a palatable or unpalatable food but were told they were not allowed to eat the food. Participants were then asked to complete a task

27 Hedonic Hunger 16 that required self-control resources, in which self-control was measured as persistence in an unsolvable task. As stated above, Lowe and Butryn (2007) suggest that individuals who are exposed to palatable food in the absence of an energy deficit may experience hedonic hunger, and that hedonic hunger may be elicited more in individuals who have a greater power of food. It is possible that, when hedonic hunger is elicited by the presence of a palatable food, and an individual is not allowed to consume the food, self-control depletion may occur (Lowe & Butryn, 2007). Further, self-control depletion may be greater for individuals who have a greater tendency toward preoccupation with food (Lowe & Butryn, 2007, Lowe et al., 2008). Based on this theory, the following hypotheses were made: Hypothesis 1a: Individuals who indicated more of a tendency toward preoccupation with food, or greater power of food as measured by the PFS, would demonstrate greater self-control depletion following exposure to a situation eliciting hedonic hunger than individuals who indicated less power of food. Hypothesis 1b: Self-control depletion would not differ between individuals with lower and higher power of food following exposure to a situation not meant to elicit hedonic hunger. Next, as outlined above, a study by Vohs and Heatherton (2000) found that physiologically-hungry, restrained eaters faced with higher temptation of a palatable food demonstrated greater self-control depletion than restrained eaters faced with less temptation of a palatable food. Although self-control depletion in restrained eaters has not been examined in the context of hedonic hunger, it is possible that restrained eaters also experience self-control depletion when they are resisting palatable foods in the absence of physiological hunger. Therefore, the following hypotheses were made:

28 Hedonic Hunger 17 Hypothesis 2a: Individuals who were higher in dietary restraint would demonstrate greater self-control depletion following a situation intended to elicit hedonic hunger, than individuals who were lower in dietary restraint. Hypothesis 2b: Self-control depletion would not differ between individuals with lower and higher dietary restraint following exposure to a situation not intended to elicit hedonic hunger. As stated above, Lowe and Butryn (2007) suggest that restrained eaters may represent individuals who have a latent susceptibility to overconsume palatable food (i.e., may have a greater power of food); also, it is possible that the power of food may be one aspect of dietary restraint. Restrained eaters with greater power of food may demonstrate greater self-control depletion after exposure to a tempting food. However, the combined effects of power of food and dietary restraint on self-control depletion are unknown. Therefore, the present study explored the relationship between power of food and dietary restraint, as well as their combined contribution to self-control depletion, when exposed to either a situation eliciting hedonic hunger or a situation not intended to elicit hedonic hunger. The following relationships between power of food, dietary restraint, and hedonic hunger were hypothesized: Hypothesis 3a: Following a situation intended to induce hedonic hunger, restrained individuals who were also high in the power of food would demonstrate greater self-control depletion than individuals who were either only restrained eaters or individuals who were only high in the power of food. Hypothesis 3b: For individuals who were exposed to a situation not intended to induce hedonic hunger, dietary restraint and power of food would not impact self-control depletion in a subsequent task.

29 Hedonic Hunger 18 METHOD Participants Participants were 129 undergraduate students at Bowling Green State University in Bowling Green, Ohio. The sample size was chosen to be sufficient to detect a medium effect size (Cohen, 1992). Although there are no previous studies examining the relationship between power of food and self-control depletion, studies examining the relationship between dietary restraint and self-control depletion have typically produced large effect sizes (Vohs & Heatherton, 2000; Baumeister et al., 1998). Prior effect sizes may have been large, in part, because some prior studies appear to have included both hedonic and homeostatic hunger in their experimental design, thus potentially increasing self-control demands. Having the power to detect a medium effect size was intended to protect against diminished power secondary to modifications in the experimental design that control for homeostatic hunger. Participants were recruited through undergraduate psychology classes. Students received research or extra credit for participating in the study. Recruitment materials provided basic information about the study. Informed consent was obtained from participants before they began the experimental procedure. Because the experimental protocol required that participants not be in a short-term energy deficit (i.e., hungry), participants were asked to eat a small meal or a snack one hour before participating in the study. In the event that participants forgot to eat before the study, snacks (e.g., fruit) were available. A total of 129 undergraduates completed the experiment. However, 11 participants data were excluded because the participants did not follow the instructions during the experiment, and five participants data were excluded due to experimenter errors when following the experimental protocol. One participant s data were excluded because English was not his primary language and he could not comprehend the basic vocabulary of the questionnaires. Seven of the

30 Hedonic Hunger 19 remaining participants data were excluded because they did not end the task before the 30 minute limit and had to be stopped, making it impossible to determine how long they would have persisted if they had been given unlimited time. Therefore, analyses were conducted with 105 participants (see Appendixes J and K for the regression table and interaction plots for the 112 participants who completed the experiment without participant or experimenter errors). The mean age of participants was 19.7 (SD = 1.7). Approximately 71% of the participants were female (n = 75). Approximately 71% were Caucasian (n = 75), 20% were African American (n = 21), and approximately 9% reported other ethnicities (n = 9). The mean BMI (kg/m 2 ) was 23.9 (SD = 3.9, range = ). Approximately 20% (n = 21) of the participants responded yes to the question, Are you currently dieting to lose weight? On average, pre-experiment subjective hunger ratings were low (M = 1.5, SD =.68 on a 4-point scale), and most participants had eaten within the hour before participating in the experiment (n = 84, 80.0%). Study Design Participants were randomly assigned to one of two groups: hedonic hunger or nonhedonic hunger. Following random assignment, participants completed a demographic questionnaire, a mood scale, a self-control demands measure, and a social desirability measure (see Measures). Next, participants completed a food-exposure task. Following the food-exposure task, participants completed a self-control task (unsolvable anagrams). Persistence at the selfcontrol task (length of time participants attempted to complete the anagrams prior to quitting) was used as an indication of self-control reserve. Participants also completed measures of dietary restraint, power of food, food palatability, mood, and craving following the self-control task. Measures Demographic questionnaire. Participants completed a basic questionnaire assessing demographic information (e.g., gender, age, race, height, weight, dieting status, perceived

31 Hedonic Hunger 20 hunger; see Appendix A). Height and weight were used to calculate BMI (weight in kg/height in m 2 ). Mood. Prior to the food exposure task and following the anagrams task, participants were asked to provide reports of their mood. Mood was assessed using the Positive and Negative Affect Scale (PANAS; Watson, Clark, & Tellegen, 1988; see Appendix B). The PANAS is a 20- item measure, consisting of ten positive (e.g., enthusiastic, proud) and ten negative (e.g., irritable, afraid) adjectives, representing Positive Affect (PA) and Negative Affect (NA) scales, respectively. Participants were asked to rate to what extent they feel this way right now, that is, at the present moment on a five-point Likert scale from (1) very slightly or not at all to (5) extremely. The internal consistency reliabilities of both the PA and NA scales have been found to be high, and the correlation between the scales has been found to be low (Watson et al., 1988). Chronbach s alpha in the current study was.85 for the pre-exposure PA scale and.81 for the NA scale. Alpha was.86 for the post-anagrams PA scale and.71 for the NA scale in the current study. The correlation between the pre-exposure PA and NA scales was.14, and was.00 between the post-anagrams PA and NA scales. Social desirability. The Marlowe-Crowne Social Desirability Scale (MCSDS) was used to assess participants social desirability (Crowne & Marlowe, 1960, see Appendix C). The MCSDS is a 33-item self-report true-false questionnaire that assesses the need of participants to obtain approval by responding in a culturally-sanctioned manner. Eighteen of the items are keyed true and 15 are keyed false for socially desirable responses (behaviors culturally approved of but unlikely to occur). Higher scores on the MCSDS indicate higher levels of social desirability. The test-retest reliability over a one month interval has been found to be.89. The internal consistency of this scale was adequate, with an alpha of.78 in the current study.