  Mobile health (mHealth) applications are a powerful medium for providing
behavioral interventions, and systematic reviews suggest that theory-based
interventions are more effective. However, how exactly theoretical concepts
should be translated into features of technological interventions is often not
clear. There is a gulf between the abstract nature of psychological theory and
the concreteness of the designs needed to build health technologies. In this
paper, we use SARA, a mobile app we developed to support substance-use research
among adolescents and young adults, as a case study of a process of translating
behavioral theory into mHealth intervention design. SARA was designed to
increase adherence to daily self-report in longitudinal epidemiological
studies. To achieve this goal, we implemented a number of constructs from the
operant conditioning theory. We describe our design process and discuss how we
operationalized theoretical constructs in the light of design constraints, user
feedback, and empirical data from four formative studies.
