Social contextual influences on unhealthy food consumption : A psychological approach

Summary

The current physical food environment, characterized by a high availability energy-dense, palatable foods, is widely held responsible for unhealthy dietary patterns. However, our understanding of how the unhealthy food environment steers unhealthy food consumption, and how this may be of particular importance for individuals with low socioeconomic status, is still limited. The aim of this thesis is to provide insights into potential psychological processes that may explain how aspects of the physical food environment and socioeconomic context may steer unhealthy food consumption. Psychological theories on contextual influences on motivational and decision-making processes are applied specifically to the food environment and food consumption. Part 1 of this thesis (Chapters 2 and 3) focuses on social norms that may be communicated by physical food environments and thereby influence consumption. In part 2 (Chapters 4 and 5), the focus is on resource scarcity and relative deprivation, which may explain how an individual’s deprived socioeconomic context stimulates unhealthier food consumption when unhealthy foods are readily available.
In Chapter 2, the aim is to provide a new understanding of how micro food environments may influence consumption, by proposing that social norms are embedded in physical cues in these environments. In this photo study, in-store/restaurant food environments were analysed through a social norm lens. It was demonstrated that a great variety of physical cues in self-service food environments (e.g. food traces, covered presentation, product availability) may communicate normative messages about other consumers’ behaviour or the popularity of/demand for a product (i.e. descriptive norms) and/or the appropriateness of consumption (i.e. injunctive norms). Among a sample of laypeople, a descriptive norm concerning others’ behaviour appeared easier to recognize than an injunctive norm regarding informal rules about appropriate behaviour. Findings suggest that social norms may be inferred from a wide variety of physical cues in the outside-the-home, in-store/restaurant food context.
In Chapter 3, the proposition that the physical food environment conveys social norms regarding common and appropriate consumption is examined on the level of the built, neighbourhood environment. We tested whether social norm perceptions regarding fast food consumption in the neighbourhood mediated the relationship between residential exposure to fast food outlets and fast food consumption. Fast food outlet exposure was objectively assessed as the count of fast food outlets within a 400m walking distance buffer around the postcodes of Dutch panel respondents. No direct association between residential fast food exposure and frequency of fast food consumption was found. However, both descriptive and injunctive social norms mediated the association between exposure and consumption. Those who were more exposed to fast food outlets in their direct neighbourhood perceived ‘unhealthier’ social norms, and these ‘unhealthier’ norms were in turn associated with a higher frequency of fast food consumption. Hence, this chapter provides first correlational evidence for the idea that social norms may be inferred from the built physical food environment.
In Chapter 4, the aim is to experimentally examine whether experiences of resource scarcity in an absolute sense (i.e. having too few resources) result in a higher consumption of available snacks. Scarcity experiences, including trade-off making, have been proposed to lead to a decreased mental bandwidth and so more impulsive behaviour. In our studies, resource scarcity was manipulated by a self-developed trade-off task, in which participants’ resources were either restricted (scarcity condition) or unrestricted (no-scarcity condition). Two laboratory experiments were conducted among students of Wageningen University. In the first experiment, a non-hypothesized interaction effect between scarcity and hunger bordered on significance. Scarcity appeared to increase snack consumption under low, but not high, hunger levels. In the second experiment, a difference in snack consumption between the two conditions could not be replicated, although participants were explicitly instructed to have eaten prior to participation so as to reduce their level of hunger. Overall, we could not provide conclusive evidence for the notion that resource scarcity results in unhealthier food consumption.
 In Chapter 5, the aim is to test whether the experience of personal relative deprivation (PRD, i.e. being worse off than others) results in a higher preference for palatable, high-caloric snack-type foods. PRD has been demonstrated to increase the preference for immediate, small rewards over larger benefits in the long term. In our studies, PRD was manipulated by a computer game in which participants experienced that they earned fewer resources (PRD condition) versus equal resources (control condition) relative to an opponent. The points earned served as resources to be spent on foods in a grocery shopping task. In an online experiment, no main effect of PRD on food choice was found. However, the manipulation appeared to have a differential effect for different levels of chronic PRD. A higher number of snack-type food products was selected by participants that were relatively deprived and also experienced higher chronic relative deprivation. In a lab-in-the-field experiment, where a diverse community sample made real (non-hypothetical) food choices, it was demonstrated that those in the PRD condition selected more snack-type foods compared to those in the control condition, when particularly sensitivity to palatable food was controlled for. Although results need to be interpreted with caution, this study revealed some preliminary evidence that relative deprivation results in unhealthier food choices.
 Overall, findings from part 1 indicate that the real-world physical food environment may be a relevant source of social norm perceptions about what is common and appropriate food consumption. Moreover, these findings highlight the importance of human social cognition when a person is interpreting physical contexts, as they show that perceptions of social norms may be a psychological mechanism in the relation between the physical food environment and consumption. The findings in part 2 are somewhat inconclusive, but they indicate that deprivation in a relative sense through upward social comparison may result in unhealthier food choice, but that deprivation in an absolute sense does not consistently result in unhealthier food consumption. In a practical sense, this thesis suggests that social norms and PRD may be relevant psychological processes that need to be considered when the aim is to stimulate healthier consumption and reduce socioeconomic disparities in diet.