Evidence of a self-serving bias in people's attributions for their food intake.

People often fail to acknowledge external influences on their food intake, but there might be some circumstances in which people are willing to report that those external factors influenced their behavior. This study examined whether participants who believed that they had overeaten would indicate that the portion size they were served influenced their food intake. Participants (119 women) ate a pasta lunch at two separate sessions, one week apart. At the second session, participants were randomly assigned to receive either a regular portion of pasta (the same portion as the first session) or a large portion of pasta (a portion that was twice the size), and to receive false feedback about their food intake indicating that they had either eaten about the same as or substantially more than they had at the previous session. Participants were then asked to indicate the extent to which the amount of food served influenced how much they ate at that second session. Compared to participants who were informed that they had eaten the same amount across the two sessions, those who were informed that they ate more at the second session reported a stronger influence of the amount of food served if they also received a large portion of pasta, but not if they received a regular portion of pasta. These findings suggest that the willingness to implicate external influences (e.g., portion size) on one's food intake may be driven by a self-serving bias, providing an "excuse" for overeating. However, the external cue must be salient enough to be a plausible explanation for one's behavior.

Influence of social-normative information on the modeling of food-related decisions.

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 modeling of food-related decisions. Using a novel online decision-making paradigm, female participants (total N = 1042) were provided with information about how many cookies previous participants had supposedly selected (no information was provided in the control condition), and then decided how many cookies they would choose for a snack. When there was a clear and consistent norm, the typical social modeling effect was observed. When there was a small number of "dissenters" whose responses conflicted with the norm set by the majority, participants' cookie selection still conformed to the behaviour of the majority (Studies 1 and 2). It was only when the behaviour of the previous participants was highly ambiguous that participants behaved as if they had been given no normative information (Study 3). By demonstrating that, except in extreme cases, people use the available information to discern a social norm that influences their behaviour, these findings highlight the power of social norms related to food-related decisions.

What is restrained eating and how do we identify it?

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 endeavor. We discuss how to define and measure restrained eating, specifying key attributes, and acknowledging the problems inherent in relying on self-report instruments. We conclude that given the difficulties in defining such constructs as restrained eating, we need to specify more clearly exactly what our research questions are, in order to be sure that we are identifying the populations with the attributes necessary to answer those questions.

Modeling of food intake among restrained and unrestrained eaters.

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 (total N = 735 female participants; 305 restrained eaters, 430 unrestrained eaters). Each study: (a) included a low-intake norm, a high-intake norm, and a no-norm control condition; (b) measured participants' food intake; and (c) included the Restraint Scale as a measure of dietary restraint. There were no differences between restrained unrestrained eaters in the no-norm control condition or in the magnitude of the inhibition effect (i.e., the difference between the low-intake norm condition and the control condition). There was, however, a restraint difference in the magnitude of the augmentation effect (i.e., the difference between the high-intake norm condition and the control condition). Restrained eaters showed a larger augmentation effect (d = 0.58; 95% CI = 0.29, 0.87) than did unrestrained eaters (d = 0.20; 95% CI = -0.05, 0.45). Social norms provide an upper limit for acceptable food intake, with high-intake norms permitting (but not requiring) individuals to indulge themselves. The fact that restrained eaters were more responsive to the high-intake norm than were unrestrained eaters suggests that the high-intake norm gives restrained eaters permission to indulge when they typically eat less than they want to.

What does it mean to overeat?

"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 "overeating" (1 = Does not capture the meaning at all; 7 = Captures the meaning perfectly). Results showed that eating outside of hunger was viewed as being most strongly linked to the conceptualization of overeating; mindless eating, eating more than some normative amount, and a lack of restriction were all moderately linked to the conceptualization of overeating; and the quality of the food/eating style was rated as least relevant to the conceptualization of overeating. Participants with a higher BMI, participants who perceived themselves as fat, restrained eaters, and participants with an indication of eating pathology rated all of the constructs as more relevant to the concept of overeating than did their respective counterparts, but their overall pattern of responding was the same. The present research provides some initial insights into people's thoughts on what it means to "overeat," which is important given that simply believing that one has overeaten (regardless of the actual amount consumed) can have adverse psychological and behavioral consequences. These insights provide an avenue for future research to explore whether lay conceptions could be more adaptively reshaped to reduce the negative effects of perceived overeating.

The effect of the spatial positioning of a healthy food cue on food choice from a pictorial-style menu.

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 salad was manipulated to be presented either (a) in the middle, (b) at the end, or (c) separated by 5 cm to the right of the line of unhealthier food options. Participants also completed a questionnaire measure of dietary restraint. Participants were significantly more likely to choose the salad when it was presented separately rather than in the middle of the unhealthier food options. This effect was not moderated by dietary restraint. The findings point to the possibility of designing pictorial menus in fast-food outlets in such a way as to subtly nudge people towards making healthier food choices.

It's all in the timing: The effect of a healthy food cue on food choices from a pictorial menu.

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 (before or simultaneously with food options) on food choices. Participants (n = 210) were presented with a pictorial café-style menu displaying a healthy food cue (basket of fruit and vegetables) either on the menu cover or inside the menu, or they received a control menu. Participants were asked to make one choice from each of three menu sections (meals, beverages, afters), and then completed a measure of dietary restraint. As predicted, participants chose a greater proportion of healthy food from the healthy-cue-before menu compared to both the healthy-cue-simultaneous and control menus. Furthermore, this effect was stronger for restrained eaters. The findings demonstrate that the timing of presentation of a healthy food cue is critical, and could be used to inform the design of menus in real-world environments, such as cafés and fast-food outlets, to promote healthier dietary choices.

Two observational studies examining the effect of a social norm and a health message on the purchase of vegetables in student canteen settings.

There is some evidence from laboratory-based studies that descriptive social-norm messages are associated with increased consumption of vegetables, but evidence of their effectiveness in real-world settings is limited. In two observational field studies taking an ecological approach, a vegetable-related social norm (e.g. "Did you know that most students here choose to eat vegetables with their meal?"), and a health message (e.g. "Did you know that students who choose to eat vegetables have a lower risk of heart disease?") were displayed in two different student canteens. Purchases were observed during three stages: baseline, intervention (when the posters were displayed) and immediate post-intervention (when the posters had been removed). Study 1 (n = 7598) observed the purchase of meals containing a portion of vegetables and Study 2 (n = 4052) observed the purchase of side portions of vegetables. In Study 1, relative to baseline, the social-norms intervention was associated with an increase in purchases of vegetables (from 63% to 68% of meals; OR = 1.24, CI = 1.03-1.49), which was sustained post-intervention (67% of meals; OR = 0.96, CI = 0.80-1.15). There was no effect of the health message (75% of meals at baseline, and 74% during the intervention; OR = 0.98, CI = 0.83-1.15). In Study 2, relative to baseline, there was an effect of both the social norm (22.9% of meals at baseline, rising to 32.5% during the intervention; OR = 1.62, CI = 1.27-2.05) and health message (rising from 43.8% at baseline to 52.8%; OR = 0.59, CI = 0.46-0.75). The increase was not sustained post-intervention for the social norm intervention (22.1%; OR = 0.59, CI = 0.46-0.75), but was sustained for the health intervention (48.1%; OR = 0.83, CI = 0.67-1.02). These results support further testing of the effectiveness of such messages in encouraging healthier eating and indicate the need for larger-scale testing at multiple sites using a randomised-controlled design.

Are there different types of dieters? A review of personality and dietary restraint.

We review the research on the association between personality and dietary restraint as measured by commonly-used self-report assessment instruments (Restraint Scale, TFEQ, DEBQ, and EDE-Q). In order to expand our understanding of the potentially different types of dieters, we examine the different personality profiles that emerge from existing studies of restraint and personality, including associations between restraint and body dissatisfaction and body focus, self-esteem, neuroticism, sensation seeking, impulsivity, perfectionism and narcissism. This research provides some preliminary evidence that different measures of restraint are associated not only with different eating behaviours, but that they capture different personality profiles.

Hunger, taste, and normative cues in predictions about food intake.

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 food a person would eat. Participants (n = 364) read a series of vignettes describing an eating scenario and predicted how much food the target person would eat in each situation. Some scenarios consisted of a single eating cue (hunger, taste, or a normative cue) that would be expected to increase intake (e.g., high hunger) or decrease intake (e.g., a companion who eats very little). Other scenarios combined two cues that were in conflict with one another (e.g., high hunger + a companion who eats very little). In the cue-conflict scenarios involving an inhibitory internal/sensory cue (e.g., low hunger) with an augmenting normative cue (e.g., a companion who eats a lot), participants predicted a low level of food intake, suggesting a bias toward the internal/sensory cue. For scenarios involving an augmenting internal/sensory cue (e.g., high hunger) and an inhibitory normative cue (e.g., a companion who eats very little), participants predicted an intermediate level of food intake, suggesting that they were influenced by both the internal/sensory and normative cue. Overall, predictions about food intake tend to reflect a general bias toward internal/sensory cues, but also include normative cues when those cues are inhibitory. If people are systematically biased toward internal, sensory, and inhibitory cues, then they may underestimate how much food they or other people will eat in many situations, particularly when normative cues promoting eating are present.

Using a descriptive social norm to increase vegetable selection in workplace restaurant settings.

OBJECTIVE: Recent work has shown that exposure to social norm messages may enhance the consumption of vegetables. However, the majority of this work has been conducted in laboratories, often with student populations. Little is known about whether this approach can be successfully used in other contexts. In this study, a poster featuring a message based on social norms was tested to examine whether it could increase and maintain the purchase of meals with vegetables in workplace restaurants. METHOD: A pretest-posttest design with 3 phases was used in 3 workplace restaurants in the United Kingdom. The first 2 weeks formed the preintervention phase, the second 2 weeks the intervention phase, and the last 2 weeks the postintervention phase. During the intervention phase only, posters containing a social norm message relaying information about vegetable purchases of other diners were placed in each restaurant. The main outcome measure was the percentage of meals purchased with vegetables, which was analyzed using Pearson's chi-squared test. RESULTS: Participants were judged to be male (57%), not overweight (75%), and under the age of 60 (98%). The intervention was positively associated with the percentage of meals purchased with vegetables: baseline versus intervention (60% vs. 64% of meals purchased with vegetables; p < .01); intervention versus postintervention (64% vs. 67% of meals purchased with vegetables; p < .01); and baseline versus postintervention (60% vs. 67% of meals purchased with vegetables; p < .001). CONCLUSIONS: Social norm messages may increase the purchase of vegetables in workplace settings. (PsycINFO Database Record

The social facilitation of eating or the facilitation of social eating?

People eat more when they eat in groups. Various explanations have been offered for this "social facilitation" of eating. We consider these explanations and find most of them wanting, especially insofar as they do not take into account the increased per capita provision of food when people eat together. We suggest that people often prefer to eat in groups precisely because it offers them an opportunity to overindulge.

Self-reported overeating and attributions for food intake.

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 they normally eat for lunch, resulting in three intake-evaluation categories: 'ate less', 'ate about the same' or 'ate more'. MAIN OUTCOME MEASURES: How much participants ate; the extent to which they attributed their food intake to an internal cue (i.e. hunger) and an external cue (i.e. the amount of food served). RESULTS: Participants served a large portion ate more than those served a small portion, but the magnitude of the portion-size effect did not vary across intake-evaluation categories. Furthermore, although participants in all groups indicated that their hunger influenced how much they ate, only those in the 'ate more' group indicated that the amount of food available influenced how much they ate. CONCLUSION: People appear to be willing to explain their food intake in terms of an external cue only when they believe that they have eaten more than they normally would.

Restrained Eating and Food Cues: Recent Findings and Conclusions.

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 attractive food cues by eating more but unrestrained eaters show less responsiveness and extending this work to examine the mechanisms that might underlie this differential responsiveness. Labeling a food as healthy encourages more eating by restrained eaters, while diet-priming cues seem to curtail their consumption even in the face of attractive food cues. Work on cognitive responses indicates that restrained (but not unrestrained) eaters have both attention and memory biases toward food cues. Restrained eaters attend more strongly to food- and diet-related cues than do unrestrained eaters, as evidenced in both their eating behavior and their attention and memory responses to such cues. These effects interact with expectations and manner of presentation of such cues. What remains to be understood is the meaning and mechanism of the attention bias toward food cues in restrained eaters and the implications of such bias for overeating and overweight more broadly speaking.

Conflicting internal and external eating cues: Impact on food intake and attributions.

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 than external cues (i.e., other people's behavior) would be apparent when those cues are in conflict with one another. METHOD: Female participants (n = 104) took part in a pizza taste test after having been food deprived for 18-hr or after consuming a meal-replacement preload. Half of the participants were also exposed to a social norm that conflicted with their deprivation condition: deprived participants were exposed to a low-intake norm, whereas preloaded participants were exposed to a high-intake norm. After completing the taste test, participants indicated the extent to which their food intake was influence by how hungry they were and how much other people ate. RESULTS: Deprived participants ate less when exposed to a low-intake norm than when no norm was present, but reported that the behaviors of others had no impact on their food intake. In contrast, preloaded participants did not eat significantly more when exposed to a high-intake norm, but reported that the behavior of others made them eat more. CONCLUSIONS: Participants are generally inaccurate in the attributions they make for their food intake, and we suggest that these inaccuracies may be because of motivated misreporting. (PsycINFO Database Record

The persistence of and resistance to social norms regarding the appropriate amount to Eat: A preliminary investigation.

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 portion of the experiment examining resistance to social influence, participants given an initial opportunity to form a personal eating norm by eating alone for one session in the absence of social influence were no more resistant to low eating norms than were those who had no such opportunity; however, those who ate alone for two or three prior sessions did show resistance. For the high eating norm, it took three eating alone sessions to create resistance. In the portion of the experiment examining persistence of social influence, when participants ate alone following a session with norm-setting remote confederates, the effect of the social influence persisted. However, the persistence effect varied by norm and weakened over time. Participants modeled a low eating norm for only one additional session and the size of the effect was markedly weaker. By contrast, the high norm persisted for all of the remaining sessions. Thus, individuals' social influence histories can affect their eating.

Contextual cue exposure effects on food intake in restrained eaters.

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 differences moderate the impact of exposure to such a food cue among restrained eaters. To this end, we compared the effect of exposure to a low calorie food cue either on its own or together with a high calorie food cue. Specifically, we exposed 122 undergraduate women to a low calorie food cue (pictures of grapes), or to a high calorie food cue (pictures of cookies), or both, and examined the effect of such food-cue exposure on intake of either grapes or cookies. Restrained eaters were identified by their scores on the Revised Restraint Scale (Herman & Polivy, 1980). In line with predictions regarding dieting goal activation, restrained eaters ate less of the given food, either grapes or cookies, following exposure to the grapes cue alone than after exposure to the grapes+cookies cue. Thus the context in which a low calorie food cue is presented (alone, or in combination with a high calorie food cue) may play an important role in how much restrained eaters eat. The findings have implications for the regulation of food intake in restrained eaters.

What does it mean to eat an appropriate amount of food?

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: 121 university students (73% women) and 107 community members (100% women). Participants were asked to rate the extent to which several statements reflected the concept of "appropriate food intake" or "normal food intake" (1=Does not capture the definition at all; 7=Captures the definition perfectly). These statements included items referring to external eating cues (e.g., "Eating as much as other people", "Eating the entire portion of what you are served") and items referring to internal eating cues (e.g., "Eating an amount that will make you feel satisfied") or nutritional needs (e.g., "Eating a healthy amount"). Repeated measures ANOVAs indicated that participants consistently defined appropriate/normal intake in terms of internal eating cues and nutritional needs. In contrast, despite evidence indicating that perceptions of how much is an appropriate amount to eat are affected by external eating cues, external eating cues were ignored in participants' definition of appropriate/normal intake. The disconnect between how people define appropriate intake (i.e., in terms of internal cues) and what research shows affects norms of appropriateness (i.e., external cues) may reflect people's general unwillingness to acknowledge the influence of external eating cues on their food intake.