Persuasive Design in a Digital Mindfulness Intervention: A Randomized Trial of a Skill-Based Achievement System and...

Adherence to digital health interventions remains a persistent challenge, limiting their effectiveness and motivating the need for scalable strategies that promote sustained engagement. This randomized controlled trial investigated whether user adherence could be enhanced by two specific persuasive design strategies: a gamification approach focused on visualizing skill progression, and a social support approach based on automated interaction between supportive partners. University students were recruited and assigned to a control, gamification, or social support group. The control group received the standard intervention without persuasive strategies, whereas the gamification group utilized skill-based progression systems and infographics. In the social support group, participants were paired into teams. Participants were encouraged to motivate teammates to complete daily diary entries, with mutual completion triggering a congratulatory email. Average module completions were: control ( $M=2.52$ , SD = 1.92), gamification ( $M=2.69$ , SD = 1.89), and social support ( $M=2.76$ , SD = 2.03). Neither the gamification components nor the automated peer support system improved adherence compared to the control. Although the peer support strategy in the social support group recorded more diary entries, this did not translate to improved module adherence. User experience ratings were comparable in all groups, indicating that the strategies did not affect usability. The smaller-than-planned sample size and higher attrition rates warrant cautious interpretation of these findings. These results contribute to healthcare informatics by demonstrating the limitations of generic persuasive strategies and highlighting the need for more adaptive, context-aware engagement mechanisms in digital interventions.