Design of Health Behavior Change Support Systems: Insights from Effective Interventions, User Perceptions, Usage Data, and Safety Needs

Digital health interventions (DHIs) have numerous benefits including supporting users to change, adopt, and maintain healthy lifestyles and self-manage various health conditions. This dissertation aims to investigate factors that influence the effectiveness of DHIs designed to support behavior change. The findings of a systematic literature review and meta-analysis confirm that persuasive design principles can contribute to the effectiveness of DHIs designed to support behavior change. An analysis of the usage of content and features in a DHI showed that complying with the dosage delivered or received led users to the desired outcome. This highlights the importance of predetermining the optimal dosage needed for an intervention to achieve the desired outcomes. Additionally, we discovered that features in the primary task support, dialogue support, and credibility support affect the persuasiveness of a system and the intention to continue its usage. Other factors such as unobtrusive design, transparency, perceived effort, and effectiveness also influenced the persuasiveness of a system. The findings of this thesis also contribute to explaining the system-related factors in the technology acceptance model. Finally, there is a need to ensure that DHIs are safe for their users. Safe DHIs are crucial for ensuring users’ confidence, and compliance, and these subsequently, affect the effectiveness of DHIs. The dissertation provides rich insights for researchers, designers, and developers of DHIs that support behavior change.