Janet Polivy's research while affiliated with University of Toronto and other places

Publications (232)

Article
Social modeling is a powerful influence on people's food intake: When there is a clear and consistent norm, people eat more when eating with someone who eats a lot and eat less when eating with someone who eats only a little. In three studies, the present research examined how clear versus ambiguous social-normative information influences the model...
Article
Defining and measuring such qualities as restrained eating or dieting may require more than simply administering questionnaires and assuming that we are identifying the population that we wish to study. Different questionnaires may identify different types of restrained eaters, and even deciding what restrained eating consists of is a complicated e...
Article
The Theory of Normal Eating suggests that how much others eat sets an upper limit for how much it is appropriate to eat. This study tested the hypothesis that restrained eaters, who typically eat less than they want to, would be more responsive to a high-intake norm than would unrestrained eaters. Data were combined from 8 experimental studies (tot...
Article
“Overeating” is a significant public health concern, but little is known about how lay people conceptualize overeating. This study explored participants' conceptions of overeating. Participants were 175 university students and 296 community members (56% women) who were asked to rate the extent to which several statements reflected the concept of “o...
Article
This study examined the effects of food-based social comparisons on hedonic ratings and consumption of a meal. Participants were randomly assigned to one of three experimental conditions in which they were led to believe that they got a worse meal, a better meal, or the same meal as another participant. They then tasted and rated their own meal. Su...
Chapter
Modeling of food intake refers to the tendency for people to adjust the amount of food they eat to approximate the amount eaten by their eating companion. People eat more when eating with someone who eats a lot, and they eat less when eating with someone who eat very little. In this chapter, we summarize the research documenting the modeling effect...
Chapter
People eat differently when eating with another person than they do when eating alone. Specifically, we tend to eat similarly to those with whom we eat, sticking more closely to eating norms, and mimicking what and how much our eating companions consume. Eating together and eating according to similar cultural norms or rules has been shown to be a...
Chapter
What we choose to eat, and how much we eat, are powerfully affected by the behavior of other people, as we have seen. To a large extent, we base our food choices on what others choose, and we tend to eat more or less depending on whether our eating companions eat more or less (modeling). We also choose to eat particular foods so as to make a positi...
Chapter
Even before deciding how much to eat, people usually have already chosen what they are going to eat. Food choice and food preferences are determined in part by biological factors, but social factors play an important role. Studies of modeling show that young children and young adults imitate the food choices of others. This is true when the options...
Chapter
In the previous chapter, we considered the idea that the amount of food that a person eats is often used by others as a basis for inferences about that person; we referred to these inferences as “consumption stereotypes.”
Chapter
Before we examine in detail some of the extensive research on social influences on eating, it’s important to discuss two general kinds of concerns about research: methodological concerns and ethical concerns. Both limit what researchers do while conducting research. Methodologically speaking, for research to tell us anything useful, it must be desi...
Chapter
Research on modeling, consumption stereotypes, and impression management is consistent with our theory emphasizing norms of appropriateness. In this chapter we turn to some bodies of research that are less obviously related to norms of appropriateness; however, we believe they are related. The basic idea is that people can figure out what and how m...
Chapter
A large literature shows that people compare themselves to others on a wide variety of dimensions; this is called social comparison. Such comparisons to other people can provide useful guides for our behavior, and they may also have emotional consequences, affecting our self-esteem and happiness. We compare ourselves to others with respect to our f...
Chapter
People form impressions of others based on how much those others eat—we refer to these judgments as “consumptions stereotypes”. For example, people who eat large amounts of food are often viewed as more masculine and less feminine than are people who eat small amounts of food. Given the existence of these consumption stereotypes, people can use the...
Chapter
Social factors play a critical role in determining people’s food intake, but are they aware of the influence that these social factors have? In this chapter, we review evidence related to three key questions about awareness: (1) Do people notice how much others eat? (2) Are people aware of how much they eat in social situations? (3) Are people awar...
Chapter
Overeating can refer to eating more than we had intended to eat, eating more than our eating companions eat, or eating more than norms dictate is an appropriate amount. The act of overeating, however it is defined in a particular situation, has effects on people. These effects may be cognitive (i.e., related to our thoughts), emotional, or behavior...
Chapter
At the end of the Introductory chapter, we alluded to our Theory of Normal Eating. In this chapter, we will flesh out that theory and elaborate on some of the ideas we presented earlier.
Article
The present study aimed to investigate the effect of the spatial positioning of a healthy food cue in the context of unhealthy food cues on subsequent food choice. Undergraduate women (N = 143) were asked to choose a food from a pictorial-style menu that presented a salad and three unhealthier food options in a horizontal line. The position of the...
Article
The contemporary food-rich environment has been consistently linked to unhealthy eating. Emerging research suggests that changing the presentation context of unhealthy foods by introducing a subtle nudge in the form of a healthy food cue may promote healthier dietary choices. This study investigated the effect of the timing of a healthy food cue (b...
Book
This book examines how the social environment affects food choices and intake, and documents the extent to which people are unaware of the significant impact of social factors on their eating. The authors take a unique approach to studying eating behaviors in ordinary circumstances, presenting a theory of normal eating that highlights social influe...
Article
Normative eating cues (portion size, social factors) have a powerful impact on people's food intake, but people often fail to acknowledge the influence of these cues, instead explaining their food intake in terms of internal (hunger) or sensory (taste) cues. This study examined whether the same biases apply when making predictions about how much fo...
Article
Full-text available
People seem to have a basic drive to assess the correctness of their opinions, abilities, and emotions. Without absolute indicators of these qualities, people rely on a comparison of themselves with others. Social comparison theory can be applied to eating behavior. For example, restrained eaters presented with a standard slice of pizza ate more of...
Article
Full-text available
Purpose of review: The purposes of the present review are to organize the recent literature on the effects of food cues on restrained and unrestrained eaters and to determine current directions in such work. Recent findings: Research over the last several years involves both replicating the work showing that restrained eaters respond to attracti...
Article
Objective: We examined whether people’s attributions for their eating behaviour differ according to whether they believe they have eaten more, less or about the same as they normally would. Design: Participants were served a small or large portion of pasta for lunch. Afterwards, they were asked to compare how much they ate in the study to how much...
Article
Food cue exposure has been shown to trigger overeating in restrained eaters. To explore the difficulties experienced by these individuals in regulating their food intake, recent investigations have sought to determine the impact of exposure to a low calorie food cue, but with mixed success. This study tested the possibility that contextual differen...
Article
We conducted a preliminary investigation on the resistance to, and persistence of, social influence regarding the appropriate amount to eat, defined in terms of eating an amount similar to that eaten by a confederate. Participants ate pizza both alone and in the presence of remote confederates presenting either a high or low eating norm. In the por...
Article
Objective: Social factors have a powerful influence on people's food intake but people typically fail to acknowledge the influence of such external cues, instead explaining their food intake in terms of factors such as how hungry they are. We examined whether the tendency to explain one's food intake in terms of internal cues (i.e., hunger) rather...
Article
Norms of appropriateness have been used to account for the influence of a variety of external eating cues (e.g., social factors, portion size) on people's food intake. What is less clear is what, exactly, “appropriate” means. This study explored participants' conceptions of appropriate food intake. Two separate samples were included in this study:...
Article
Pre-exposure to food cues has often been shown to increase food intake, especially in restrained eaters. This study investigated the role of expectations in the effect of such pre-exposure on food intake. A sample of 88 undergraduate women was exposed to visual food cues (photos of grapes and chocolate-chip cookies). In a 2 × 2 × 2 design, particip...
Article
Large portion sizes are frequently blamed for the obesity epidemic. In this paper, we examine the culpability of large portion sizes. It is true that portion sizes have increased during the obesity epidemic, but there is as yet little evidence that exposure to large portions produces significant weight gain. Furthermore, some evidence argues agains...
Article
Social influences are powerful determinants of food intake. Whereas some people are willing to acknowledge social influences on their food intake, others seem to actively deny being influenced by social cues. Across three samples (total n=835), we examined factors that prior theory and research suggest might predict people's willingness to acknowle...
Article
The portion-size effect (PSE) refers to the fact that people eat more when served larger portions. This effect is neither obvious nor artifactual. We examine the prevailing explanations (or underlying mechanisms) that have been offered for the PSE. The dominant candidate mechanism is "appropriateness"; that is, people accept the portion that they a...
Article
Full-text available
This meta-analysis provides a comprehensive quantitative assessment of research on modeling of food intake. Thirty-eight articles met inclusion criteria. Overall, there was a large modeling effect (r = .39) such that participants ate more when their companion ate more, and ate less when their companion ate less. Furthermore, social models appear to...
Article
Objective: The "unit bias" has been proposed as an explanation for the portion-size effect; people consider a single unit to be an appropriate amount to eat and thus eat more when served a larger unit than when served a smaller unit. We suggest that the unit bias might be better characterized as a "segmentation effect," such that people eat less w...
Article
Eating is a social activity for most people. Other people influence what and how much an individual chooses and eats. Such social influence on eating has long been recognized and studied, but we contend here that one important social influence factor, social comparison, has been largely overlooked by researchers. We review the literature on compari...
Article
Wansink and Chandon have examined the "mindlessness" that is often evident in everyday food intake. In this commentary, we focus on four issues raised by Wansink and Chandon's paper: (1) the distinction between food choice and food intake; (2) their model of food intake (and how it compares and contrasts with our own model of food intake); (3) the...
Article
Undergraduates (N = 2,823) at 6 universities were surveyed longitudinally to examine the relevance of student home setting on the transition to university. Preliminary results indicated that rural students seem less likely to attend large, ethnically diverse universities. Hierarchical linear models revealed that “proximal rural” students reported b...
Article
Mate selection seems to be based to some extent on appearance and physique. Assortative mating suggests that romantic partners select each other based on their similarity in important characteristics. Two studies examined the similarity in physiques of members of romantic couples. Study 1 found that the physical measurements of brides-to-be were po...
Article
The Perceived Self-Regulatory Success (PSRS) scale was developed to assess self-reported success at dieting and has been used to differentiate between successful and unsuccessful dieters (Fishbach, Friedman, & Kruglanski, 2003). We re-analyzed data from seventeen studies in order to examine whether PSRS predicted in-lab eating behavior of restraine...
Article
Objective: Two studies examined whether people are aware of social influences on food intake, and whether recognition of those influences is driven by the observation of mimicked eating and/or matching the amount of food eaten. Method: In Study 1, participants watched a video of 1 person eating alone, or a video of 2 people eating together that...
Article
Full-text available
It is often assumed that social models influence people's eating behavior by providing a norm of appropriate food intake, but this hypothesis has not been directly tested. In three experiments, female participants were exposed to a low-intake model, a high-intake model, or no model (control condition). Experiments 1 and 2 used a remote-confederate...
Article
Weight, eating attitudes, and depression were assessed in male and female students over the four years of university attendance, and the relation of weight changes to eating attitudes and depression was explored using self-report measures (Restraint Scale, EDI, CES-D) collected at six time points during the university years. Results showed that, in...
Article
We examined whether a brief education and a brief mindfulness exercise would reduce the effect of portion size on food intake. Participants were randomly assigned to one of the three information conditions (education, mindfulness, or control) and then received a small or large portion of pasta for lunch. Neither education nor mindfulness was effect...
Article
Nutritionists are well aware that people tend to underreport their weights, but psychologists still often rely on weight self-reports. The present paper reviews research on weight underreporting and attempts to identify its underlying motivations. Restrained eaters (and overweight individuals) are especially likely to underreport their weight. We e...
Article
This study investigated the natural course of eating pathology in a sample of female university students. Seventy-nine students were recruited in their first month of the university, 24 of whom endorsed objective binge eating and inappropriate compensatory behaviors based on an initial screening interview. Testing sessions occurred every 6months fo...
Article
The obesity epidemic has provoked considerable concern along with suggestions and demands for corrective measures. After surveying the basic features of the epidemic, we turn our attention to self-regulation, which is at the heart of most of the proposed solutions to the epidemic. Information, incentives, and most other tactics to get people to eat...
Article
The present study investigates the characteristics which differentiate between first-year university students who maintain their high school averages (Maintainers: n=165) and those whose averages decrease at least one letter grade (Decliners: n=435). The 600 students entered first year at one of six Canadian Universities, which varied in size and e...
Article
We studied whether self-reported intent to exert cognitive control over eating was associated with differences in brain response to food cues, independent of genetic background. Subjects were ten pairs of identical twins in which one twin was a restrained eater and the co-twin was unrestrained, as classified by the Herman and Polivy Restraint Scale...
Article
Objectives: To examine the effects of calorie labeling on food selection and intake in dieters and non-dieters, and to explore whether expectations about food healthfulness moderate these effects. Methods: Participants were presented with a menu containing two items, a salad and a pasta dish. The menu had (a) no calorie information, (b) informat...
Article
This research examines parental divorce and first-year students' transition to university. Incoming students (N = 2,724) to six diverse universities completed questionnaires in August, before university, and again in November and March. Initial baseline measures indicated that females of divorced parents reported more depressive symptoms than femal...
Article
This study investigated how attachment style predicted first-year students' responses to a transition to university group facilitation program. Participants ( N = 148) at three universities were randomly assigned to a control or facilitation group. Each group consisted of on average six first-year students and two facilitators who met weekly for ni...
Chapter
This chapter discusses the ubiquity of food cues in our environment and reviews the literature on people's responses to them. Such cues make it particularly difficult for humans to reduce, let alone control, their food intake and, particularly, to restrict their intake to the levels required for life-extension. This chapter also discusses the diffe...
Article
Manipulated perceptions of the portion size of food influence subsequent eating by restrained and unrestrained eaters. In the present study, all participants were served a same-sized slice of pizza. For one-third of participants, their slice appeared larger than the slice being served to another ostensible participant, another third perceived their...
Chapter
In this chapter, we review the research literature on sex and gender differences in hunger and eating behavior. If you ask people about these types of differences in hunger and eating, they will readily identify some: women exhibit certain distinctive cravings during pregnancy and certain phases of the menstrual cycle; men eat more than women do; m...
Article
We examined prospective relations between activity involvement and successful transitioning to university. A sample of 656 students from 6 Canadian universities completed questionnaires before beginning university and at the end of their first year. Breadth (number of different activity domains) and intensity (mean frequency) of activity involvemen...
Article
This study examined the nature of students’ out-of-class involvements with a view to identifying the kinds of involvement that are most conducive to positive adjustment to university. Students from five Canadian universities completed questionnaires in November of their first-year at university assessing the quality of their out-of-class involvemen...
Article
The present study aimed to investigate the role of social comparison processing in women's responses to thin idealized images. In particular, it was predicted that comparison with the images on the basis of appearance would lead to more negative outcomes than comparison on the basis of intelligence. A sample of 114 women viewed fashion magazine adv...
Article
We examined the relative contributions of genetic and environmental influences to restrained eating. Restrained eating was assessed by the Restraint Scale in a survey mailed to all twins enrolled in the University of Washington Twin Registry. We used structural equation modeling to estimate genetic and nongenetic contributions to restrained eating....
Article
Research suggests that caloric restriction (CR) is beneficial; however, the effects of CR in the context of food cues are unclear. A 2 (food cue vs. no cue)x2 (CR vs. ad lib) between-subjects design was employed to test these effects in 40 rats. It was predicted that cue exposure and CR would induce stress, and that these factors might interact syn...
Article
The "false-hope syndrome" suggests that unrealistic expectations are responsible for the cycle of repeated failure and renewed efforts at self-change characterizing many self-changers. Our hypotheses were that: (1) committing to a particular self-change task would inflate initial expectations, (2) participants would be unsuccessful relative to thei...
Article
Full-text available
A new scale, the Student Perception of University Support and Structure Scale (SPUSS), was developed for research on the transition to university. The scale was based on concepts derived from Baumrind's (1971) theory of parenting styles. Data were obtained from two separate cohorts of freshmen (n=759 and 397) attending six Canadian universities of...
Article
Many factors contribute to how much we eat. One such factor is the variety of different foods available. The current article reviews the variety literature with a specific focus on the factors that moderate the effects of variety on food intake and that moderate the processes that may underlie the variety effect (i.e., sensory-specific satiety and...
Article
The well-documented preference for thin female physiques that has prevailed in Western civilisations over the last few decades has produced an ever-increasing emphasis on dieting to lose weight and fit the thin ideal. Unfortunately, our research on restrained eating over the last three decades has demonstrated repeatedly that chronic dieters (whom...
Article
The main aim of this study was to investigate the effects of food-related beliefs about the healthiness of foods, restrained eating, and weight salience on actual food intake during an ad libitum snack. In a 2 (healthy vs. unhealthy) by 2 (restrained vs. unrestrained eaters) by 2 (weight salient vs. not salient) factorial design, 99 female undergra...
Article
The present study aimed to investigate the role of processing in women's responses to thin idealized images of beauty. A sample of 144 women viewed magazine advertisements containing either thin ideal or product images. Instructional set was manipulated with three levels: control, social comparison, and fantasy instructions. It was found that expos...
Article
Few factors have been identified that bolster self-control processes and prevent overeating in restrained eaters; however, research on counteractive-control theory suggests that exposure to food cues may represent such a protective factor. To further investigate the effects of food-cue exposure, restrained and unrestrained eaters were randomly assi...
Article
Freshmen students at six Canadian universities completed questionnaires that assessed the quality of match between their individual needs and their university environment. The Student-University Match Questionnaire (SUM), a theoretically derived scale, was developed and demonstrated excellent psychometric properties (Cronbach's alpha = .87). Furthe...
Article
The present study investigated the effects of exposure to a food cue on the self-reported importance of dieting in those with low, medium, and high levels of dietary restraint. The results indicated that exposure to a food cue bolstered dieting-related goals in those who were low in dietary restraint but had no effect on the importance of dieting-r...
Article
Self-reported weight changes over 7 months and their relation to psychosocial characteristics (self-esteem, depression, social support, perceived stress and transition perception) and eating attitudes and behaviors (restrained eating and Eating Disorder Inventory subscales [EDI]) were assessed in first-year male and female students at six Canadian...
Article
A growing body of research on caloric restriction (CR) in many species of laboratory animals suggests that underfeeding leads to better health and longevity in the calorically-restricted animal (e.g., see [[34]. J.P. Pinel, S. Assanand and D.R. Lehman, (2000). Hunger, eating and ill health. Am Psychol, 55, 1105-1116.], for a review). Although some...
Article
We review the history of "external cues" as an important factor in the control of human food intake. We begin with Schachter's proposal that obese individuals are especially (and perhaps exclusively) responsive to external food cues and examine subsequent modifications and challenges to that model and the decline and resurgence of research on exter...
Article
Comments on an article titled Medicare's Search for Effective Obesity Treatments: