Limited Self-Control and Food Choices Under Varying Workloads: Brain Food Isn't Health Food (in the Field)

Abstract

Capacities for self-control have consequences for the effectiveness of policies designed to assist individuals in making choices affecting their long run well-being. The strength model from the psychology literature proposes that self-control is a constrained resource whose effectiveness tends to dwindle when an individual attempts to resist multiple sources of temptation at a time. We develop a simple economic framework for the strength model, and test its consequences in the field. Specifically, we analyze the food purchase patterns of university students who face time-varying academic self-control demands. Relative purchase of unhealthy fast foods increases during the week of final exams when students’ workloads are most cognitively demanding, compared to the purchase ratio of such foods during other times of the year. To address the external validity of the field data, and assist in ruling out alternative explanations, we conduct a field survey which includes a snack choice experiment. In the experiment, the main robust and significant predictor of choosing an unhealthy snack over a healthy snack is subjects’ self-reported time needed to complete their academic responsibilities during the upcoming week. As combined evidence, these findings are consistent with an economic model of limited self-control in which individuals must choose how to allocate their self-control between academic activities and eating activities. Consequences and potential policy implications are discussed.