Reducing the Paradox of Choice: Designing a Nutritious Persuasive Shopping Trolley Ole Kallehave, Mikael B. Skov, Nino Tiainen HCI Lab, Department of Computer Science, Aalborg University Selma Lagerlöfs Vej 300, DK-9220 Aalborg Øst, Denmark ole-kallehave@rocha.dk, dubois@cs.aau.dk, ninodk@gmail.com Abstract. Healthy lifestyles is in focus at the moment while at the same time a fast growing number of people are becoming over-weight or obese. Persuasive technologies hold promising opportunities to change our lifestyles. In this paper, we introduce a persuasive shopping trolley that integrates three tools of persuasiveness namely reduction, suggestion, and self-monitoring. The trolley supports shoppers in assessing the nutrition level for supermarket products, provide suggestions for other products to buy, and displays your total behavior. An evaluation shows that the trolley can affect the behavior of shoppers. Keywords: Shopping, trolley, nutrition, persuasive 1 Introduction Persuasive technologies potentially hold the opportunity to change people’s attitudes and behaviors. Fogg states that contemporary computer technologies are currently taking on roles as persuaders including roles of influence that traditionally were filled by doctors, teachers, coaches, etc. [1]. Research studies within different disciplines are increasingly concerned with such persuasive technologies that may be used to create or change human thought and behavior. As an example, Chang et al. [2] propose the Playful Toothbrush that assists parents and teachers to motivate young children to learn proper and thorough tooth brushing skills and Arroyo et al. [3] present the Waterbot that informs and motivates behavior at the sink for increased safety and functionality and thus motivate behavior change. Both these technologies propose rather simple, yet potentially powerful input and feedback that aim to inform users of their own behavior or lack of behavior, e.g. for how long one has brushed the individual teeth. One potential application area for persuasive technologies is promotion of healthier lifestyles. In several Western societies, a fast growing number of people are either over-weight or obese, e.g. more than 50% of the adult population in Denmark are either over-weight or obese [4]. While such problems with over-weight stem from several conditions (i.e. genetic, lack of exercise, food), people generally consume food that contains too much e.g. fat or sugar. Thus, we need to alter people’s behavior and attitude while they shop groceries in supermarkets. But supermarket shopping is a