How physical cues in micro food environments influence consumption: a social norm account

Summary

In large parts of the Western world, people navigate through a range of food environments that may be characterized by a set of cues within those environments that presumably encourage undesired dietary decisions. Such environmental cues may include the abundance, easy accessibility, or strong promotion of relatively less healthy and less sustainable foods. It is as yet poorly understood how these cues actually contribute to our consumption however. The general aim of this dissertation is to improve the understanding of how physical cues in micro food environments determine our dietary decisions. Specifically, we aim to demonstrate that social norms are inferred from physical cues in food environments. We further aim to demonstrate that social norm interpretations mediate the effect of food environment exposure on food consumption. The social norm interpretation is tested among a range of different physical cues, each chapter focusing on a specific cue (Chapters 3–5), thereby aiming to distinguish between perceived descriptive norms (beliefs about what other people do in a given situation) and perceived injunctive norms (beliefs about what should be done according to other people in a given situation). The relevant alternative explanations to the social norm account are also taken into consideration in this dissertation. Chapter 1 presents the background of the thesis including a theoretical framework. Chapter 2 provides a foundation for the experimental designs applied in Chapters 3–5. To do so, an inventory was created of physical cues in Dutch outside-the-home food environments potentially communicating social norms. A set of photographs taken in different self-service food environments (Study 1, 40 photographs) was qualitatively analyzed, and the findings were then cross-validated among laypeople (Study 2, n = 173). A great variety of physical cues were structurally linked to either or both descriptive and injunctive norm connotations (e.g., ‘others have taken’, ‘appropriate to take’, respectively). Based on the results, it was posited that social norms are widely and physically embedded in food environments and may guide food consumption. The causal effect of physical cues in food environments on perceived social norms and food consumption still remained unclear however. Chapter 3 zooms in on a physical cue connected to available foods: the presence or absence of a cover on snack bowls, presumably illustrating an injunctive norm. The findings of two quasi-experimental field studies (Study 1, 40 observation periods; Study 2, n = 711) and a lab experiment (Study 3, n =151) show that a snack bowl presented with (versus without) a cover can decrease the likelihood of people taking snacks. Further, this research empirically supports the proposition that social norms in generic terms can be inferred from physical cues surrounding foods – specifically, we demonstrated that the presence (versus the absence) of a cover on snack bowls may decrease participants’ perceptions of social norms about taking snacks. Chapter 4 examines the effect of offering an increased proportion of plant-based relative to animal source foods as an example of a physical cue potentially being interpreted as a social norm encouraging plant-based food consumption among non-vegetarians. Both an online experiment (Study 1, n = 184) and a lab-in-the-field experiment (Study 2, n = 276) were performed, with different experimental manipulations simulating (online) supermarket settings and including different foods. These studies provided support for the proposition that assortment structures may shift (or shape) the ideas of non-vegetarians about what other people typically choose. We particularly showed that descriptive (but not injunctive) norms about ‘normal’ consumption can be inferred from the number of plant-based foods available. However, the direction of the descriptive norm effect remains unclear, as we observed conflicting descriptive norm interpretations of the availability manipulation in the online setting compared to the lab-in-the-field setting. Interestingly, only among the subgroup of participants showing high meat attachment patterns (moderator), we found that the availability of an increased proportion of physically present plant-based (versus animal source) foods increased the likelihood of a person choosing a plant-based food option. Chapter 5 provides first support for the notion not only that social norms are embedded in physical food environments (primarily shown in the previous chapters), but also that perceived descriptive and injunctive norms may jointly underlie the relationship between physical cues in food environments and (later) food consumption. This was shown across an online experiment (Study 1, n = 329) and a lab-based experiment (Study 2, n = 132) testing the influence of being visually exposed to, or actually being served, smaller (versus larger) portion sizes on consumption of that food 24 h later. The results showed that being served (but not being visually exposed to) smaller (versus larger) portion sizes resulted in individuals perceiving that others (a) would serve themselves a relatively smaller portion size (perceived descriptive norm) and (b) believe that a relatively smaller portion size is the appropriate amount to eat (perceived injunctive norm); this reduced portion size selection and consumption of that same food a day later when they could decide the portion size themselves. Lastly, Chapter 6 summarizes and discusses the main results of the presented work, including a theoretical and methodological reflection, followed by some directions for future research and the implications for policy and practice. In conclusion, this dissertation provides initial support for the proposition that physical cues in micro food environments may be interpreted as a descriptive and/or injunctive norm about normal and appropriate consumption. These – what I like to call – social contextual norm cues seem to be widely embedded in (self-service) food environments. The findings in this dissertation further provide some preliminary support for the proposition that perceived descriptive and injunctive norms may mediate the effect of physical cues in micro food environments (specifically, served portion sizes) on (later) food consumption. Until now, empirical support for the social norm account and its embedding in food environments was largely lacking. This dissertation thus contributes to this domain by showing preliminary evidence of the role of descriptive and injunctive norms as a potential explanatory mechanism of the effect of physical cues in micro food environments on food consumption.