The persistence of and resistance to social norms regarding the appropriate amount to Eat: A preliminary investigation
Introduction
Despite the common assumption that human eating behavior is controlled by physiological factors, there is considerable evidence supporting the importance of non-physiological factors (e.g., Herman & Polivy, 1983) as determinants of food intake. Important among such factors are social norms that proscribe eating excessively; indeed, big eaters receive the disapprobation of their peers, as do those who disregard social norms in other domains, whereas those who eat lightly attract positive attributions and approval (Vartanian et al., 2007, Vartanian et al., 2015). Herman, Roth, and Polivy's (2003) normative model posits that, in the presence of palatable food, people will eat as much as possible unless they are subjected to other pressures, such as restrictive norms governing appropriate intake. Thus, social norms serve an inhibitory function, indicating the point at which individuals must stop eating if they are to avoid the imputation of excessive intake. Information on which to base one's beliefs about appropriate (i.e., non-excessive) amounts can come from at least two sources: the behavior of others and the eating situation itself.
Herman et al., (2003) normative model presupposes that, prior to ascertaining those norms, people may be uncertain about how much to eat, and cannot rely on their introspection of hunger or satiety to provide guidance (Herman & Polivy, 2005). If the eating situation is unfamiliar, there may be uncertainty as to whether it should be viewed as a meal or a snack (Pliner & Zec, 2007), or perhaps the food provided may be unfamiliar or presented in unfamiliar units. Further, if impression-management concerns are high, people might seek normative cues from others or from the situation to prevent the social disapproval attendant upon non-normative behavior, even if they are already confident in how much it is appropriate to eat (Spanos, Vartanian, Herman, & Polivy, 2014).
There are also occasions when people have a very clear idea of how much they should be eating in that situation, although others may have different ideas. People seem to know, for example, that one submarine sandwich is an appropriate amount to eat for lunch; whether, however, the appropriate size is 6 inches or 12 inches depends upon the individual. It may be that these individual (“personal”) norms are a kind of habit (Herman & Polivy, 2005), perhaps initially based on the satiety value of a particular amount of food eaten at a particular time (Brunstrom, 2014). These personal norms may also be due to something more accidental, such as what happened to be in the refrigerator during a foraging expedition, but maintained subsequently through sheer repetition. There are few data pertaining to personal eating norms (see H. B. Lewis et al., 2015; for an exception). However, quite a few studies have examined the effects on eating of norms derived from observation of others, and from the situation.
The importance of social norms as regulators of eating may be seen in studies of modeling or conformity, in which a participant is paired with one or more experimental confederates whose eating behavior has been scripted, providing normative information. Comprehensive reviews and meta-analyses (Cruwys et al., 2015, Robinson et al., 2014, Vartanian et al., 2015) examining the effects of social modeling on food intake have consistently found that participants eating with one or more confederates follow the behavior of the confederate(s) in that they eat more or less depending on the behavior of their eating partner(s). In a review of 69 food-modeling studies (Cruwys et al., 2015), all but five provided evidence for a robust modeling effect, despite a wide array of individual differences and contextual factors among the studies. A meta-analysis (Vartanian et al., 2015) also found that this effect is fairly robust across studies (r = 0.31 in experimental studies, r = 0.56 in correlational studies). Interestingly, some people seem to be aware of this influence, accurately reporting the extent that the social norm affected their food intake (Robinson & Field, 2015), but others, with particular personalities and who do not see use of social norms as appropriate guides to intake deny such effects (Spanos et al., 2014).
In the present research we are interested in the persistence of social norms, that is, the extent to which their effects remain once the source of the normative information on which they are based is no longer present. Previous studies have shown that individuals tend to form habitual personal norms once they become familiar with a situation or context, and that this personal norm may be initially influenced by external sources (Cialdini & Trost, 1998). Therefore, individuals may internalize an eating norm provided in a laboratory context if they are repeatedly exposed to it. Moreover, individuals will continue to follow the norm even in the absence of the information that served as the basis for the norm. In one study, researchers paired children with a low and high social eating norm in one session and then held a “free” eating session a few days later (Bevelander, Anschütz, & Engels, 2012). The researchers found that overweight children modeled the high food intake norm and continued to follow it when eating alone, thus suggesting that eating norms can be internalized and persist when the model is no longer present. We wanted to examine this same question with adults and examine if eating norms would persist for more than one session.
We were also interested in answering the opposite question: Can we arrange for participants to form their own personal eating norms in the laboratory setting and thereby become resistant to subsequent socially-derived eating norms? Comprehensive reviews of the literature have shown that the social modeling effect is robust (Vartanian et al., 2015), and researchers have had difficulty finding conditions under which people will not follow socially-derived eating norms.
Still, there is reason to believe that a strong personal norm may override one's tendency to adhere to norms provided by others. For example, Deutsch and Gerard (1955) found that when individuals were asked to make judgments about stimuli before hearing the judgments of others, and then to judge the same stimuli again after hearing them, they were less likely to conform to others' judgments than were individuals who made only the post-influence judgments. Deutsch and Gerard found that all forms of commitment to their initial judgment reduced the effects of subsequent social influence, but that resistance to social influence was particularly robust when there was a record of individuals' initial commitment, as opposed to when the commitment went unrecorded. Therefore, commitment to a judgment or personal norm reduces the effects of social influence (Cialdini & Goldstein, 2004). Thus, we expect that when people form a personal eating norm, they will become (at least somewhat) resistant to the social modeling effect.
Surprisingly, very little research on eating behavior has examined the persistence of personal norms (with the exception of Bevelander et al., 2012) or resistance to social norms after formation of personal norms. Such research may yield important theoretical insights and may have practical implications for modifying eating behavior. Recently, researchers have argued that social influence may provide a powerful tool for getting people to eat in a healthier fashion (Robinson, Blissett, & Higgs, 2013).
Given the above review, we derived two hypotheses:
H1: Participants will continue to conform to eating norms established by a confederate when the confederate is no longer present.
H2: Participants will form a personal eating norm if they eat alone in the same setting multiple times and this personal norm will weaken the effects of subsequent exposure to social eating norms.
Section snippets
Overview and design
Under the pretext of examining the effects of television viewing on mood, participants watched half-hour segments of a popular television show, with the opportunity to eat pizza offered supposedly as compensation for a three-hour fast prior to each session. We examined resistance to and persistence of social norms during a period of up to four days to give participants sufficient time to form resistance to norms or to internalize our manipulated norms. Because of the logistical difficulties of
Materials
Food. We used McCain Deep ’n Delicious 3 Cheese Pizza®; 5 mini-pizzas were cut into 6 equal-sized slices, each weighing about 15 gm and containing approximately 38 calories.
Questionnaires. After viewing the recorded TV show in each session, participants completed a mood questionnaire and a “Media Rating Scale” intended to bolster the cover story. At the end of the second session, participants also completed the Restraint Scale (Polivy, Herman, & Howard, 1988) and a post-experimental
Preliminary analyses
To ensure that participants had perceived the norms differently in the high- and low-norm conditions we conducted a t-test on participants’ reports of how many pieces of pizza on average the previous participants had eaten. Participants in the low-norm conditions estimated that previous participants had eaten 4.5 (SD = 3.8) pieces of pizza, whereas those in the high-norm conditions estimated that previous participants had eaten 15.6 (SD = 7.6) pieces of pizza. A t-test using the Satterthwaite
Discussion
We found preliminary evidence that normative information affected eating behavior when it was present and could continue to affect behavior subsequently in its absence, thus providing support for our prediction of persistence. The pattern of effect sizes suggest that the high norm had large effects on our participants relative to the control condition. They also suggest that the effect persisted for all four sessions, although the influenced waned from a large effect to a medium effect by the
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