Rethinking Evaluations Of mHealth Systems For Behavior Change.

Much of the recent research in mobile health (mHealth) has focused on the development of apps and wearables for promoting healthy behavior changes, such as losing weight, increasing physical activity, or adhering to a medication regimen. These interactive systems help users make changes in their behavior by, for instance, tracking healthrelated activities and states, providing feedback, helping users set and track goals, and facilitating supportive social interactions. We refer to the features that implement such functionality as the system's "intervention components," as they are designed to actuate psychosocial mechanisms (e.g., modeling, selfefficacy, positive reinforcement, etc.) thought to mediate the behavior change process. As with any other type of behavioral intervention, mHealth systems are only effective for some users and some of the time, but insofar as they do work, they do so mainly through the mechanisms of change that are activated via users' interactions with the system's intervention components.