Evaluate Closed-Loop, Mindless Intervention in-the-Wild: A Micro-Randomized Trial on Offset Heart Rate Biofeedback

The vision of closed-loop intervention systems for behavioral health is growing with the flourishing of mobile sensors and multimodal data. There has been abundant work on identifying symptoms, diagnosis, and progression monitoring. However, there has been limited effort in intervention research, tailoring suitable interventions for closed-loop systems. About a decade ago, researchers began exploring mindless interventions-subtle interventions to change behavior, cognition, or affect with minimal attention and effort. Despite their success in controlled laboratory settings, few mindless interventions have been deployed in the real world, and none have been integrated into closed-loop systems. Thus, it remains unclear how well these low-effort, low-attention interventions integrate with sensing systems, how their effectiveness varies over time and context, and their overall impact on behavioral health management. This study is the first to deploy mindless interventions in a closed-loop system in real-world settings. We developed a closed-loop intervention for individuals with moderate to severe anxiety, delivering offset heart rate biofeedback when stress symptoms are detected. This paper presents our work-in-progress, detailing the system and study design, and highlighting this research's methodological and empirical contributions.