Abstract :
[en] Health and sustainability are becoming increasingly important in current lifestyles. In this context healthy and sustainable grocery shopping is one key aspect to facilitate a balanced and environmentally friendly diet. Many people are interested in changing their habits to become healthier and to consider their impact on the environment through the choices they make. But many do not consider where a healthy and sustainable diet starts. In other words, people frequently have a vague idea that grocery shopping is an important aspect of a healthy and sustainable lifestyle, but they lack sufficient knowledge and action plans to act accordingly. Therefore, the observable behaviour in many cases shows what is called the intention-action/behaviour gap, the attitude-behaviour gap, or the knowing-doing gap (Ajzen, 2016; Grunert, 2011; Hoek, Pearson, James, Lawrence, & Friel, 2017; de Schutter, 2015; Bailey & Harper, 2015).
To break this deadlock people, who are interested in such a lifestyle change, need the required information and support to create appropriate action plans to lead them through their grocery shopping without incurring excessive cognitive impact. The risk of such cognitive strain is that people give up easily on their good intentions and fall back into old unhealthy or environmentally impacting habits. Smartphones are ubiquitous and therefore could potentially solve many of these problems, but the design of suitable applications is mostly ad-hoc and not based on thorough modelling. On the other hand, existing behavioural models are considered to be too static and not up to the task of dynamically assessing and influencing behaviour as would be required by a smartphone-based intervention (Riley, et al., 2011; Spruijt-Metz & Nilsen, 2014).
To address these problems this work proposes three major contributions: first, a novel comprehensive model of behaviour built on well-established theories used in psychology and the social science. The novelty is the consistent integration of well-proven pre-existing theories into one single comprehensive model that aims to capture the benefits and tries to overcome the limitations of each base theory. Based on this model, the second contribution of this work is the evaluation of motivation and intention to buy healthy and sustainable groceries. It has been found that health is more important than sustainability in this regard, and that health-related goals are easier to act on than sustainability related goals resulting in a bigger intention-action gap for sustainable grocery shopping. To address these issues, the third major contribution of this work is a model-derived design framework for smartphone-based interventions that provides comprehensive guidelines for developing applications to assess and support a specific behaviour, such as grocery shopping, while at the same time aiming at addressing a superordinate issue, such as health and sustainability.
