Seminar: Self-control, stress and food consumption
PhD start-up seminar with PhD student Helene Normann Rønnow.
Summary of PhD plan
A growing share of population in many countries is becoming overweight or obese, which can be contributed to the lack of self-control among other factors. A lack of self-control can be the explanation when consumers fail their commitment to their long-term goals such as weight loss or exercising more. In economics, problems related to self-control are often explained by present biased agents and time inconsistent preferences. Theories from psychology, on the other hand, treat self-control as a limited resource, that is, an initial act of self-control will reduce the ability to exert self-control subsequently. This is referred to as ego depletion. In everyday life, individuals exert self-control in many different fields e.g. at work or studying. These events can result in (self-perceived) stress and hence influence the ability to exert self-control in other areas such as food choices.
The overall focus of this PhD project will be to investigate how stress affects the ability to exert self-control. The problem will be examined with two different methodologies: field and/or lab experiments and register and consumer scanner data. The project will also investigate which policies or tools institutions or individuals can use to mitigate self-control problems. The policies will be tested in field or lab experiments. Finally, the project will examine a policy, which is currently used to enhance healthy food choice: Food labels. The last part of the project will use scanner data from a consumer panel to investigate whether consumers, who use food labels, make healthier food choices.
Thus, the PhD project contains three parts:
Field and laboratory study of self-control, stress and food consumption
The study will investigate whether stress influence the food choices of students from different educational institutions (University and high school). Furthermore, the study will test whether a stress-reducing intervention (mindfulness) can reduce the self-perceived stress level of the students and increase self-control with respect to food choices.
The study uses a framed field experiment, that is, the students know that they are a part of an experiment, but the experiment is implemented as part of their everyday life. The study will exploit the variance in stress level, which students experience during an academic year. That is, we can observe the students in a non-stressed state in the beginning of the academic year and in a stressed state just before the exam. The study will rely on snack choices, such that we observe actual food choices rather than self-reported food intake or hypothetical choices. To infer the casual effect of an intervention on stress and snack choice, we assign the intervention randomly to some of the students.
As a pre-test to the field study or if the field study is not feasible, a laboratory experiment will be conducted to investigate the effect of stress on food choices as well as policies/tool to mitigate ego depletion.
Register and scanner data study of self-control, stress and habits
Data from GfK Consumerscan Scandinavia will be used to empirically test the predictions of a theoretical model of self-control, stress and the role of habits. Two almost similar questionnaires were sent to the GfK panel members in 2013 and 2015. The questionnaires contain questions about trait self-control, perceived stress, discount rates and attitudes towards healthy and exercising among others. The data (questionnaire and scanner data) will be combined with register data from Statistics Denmark to determine stress inducing unexpected life events such as unemployment, divorce etc. and compare it to planned life events as e.g. retirement . The study will then examine whether stress inducing life events influence the dietary quality and whether strong habits damper the effect of stress on dietary quality.
Use of food labels and dietary quality
The study will investigate whether the use of food labels influence the dietary quality, that is, whether consumers who search for food labels make healthier food choices. The study uses the same scanner data and questionnaires as described above. As a part of the questionnaire, the panel members are asked about their use of three different food labels (Description of Content, Health Claims and Nutritional Labels) at their latest shopping trip. The study will exploit the panel dimension of the data to investigate whether food label use increases the dietary quality. The scanner data will be combined with nutrient data to determine the dietary quality of the panel members.
Supervisor: Sinne Smed
Co-supervisor: Toke Fosgård