HeartPhone: Mobile Evaluative Conditioning to Enhance Affective Processes and Promote Physical Activity

Objective: Most American adults fail to achieve recommended levels of physical activity and, as a result, are at elevated risk for many chronic diseases. Affective processes have been validated as targets for increasing physical activity but are rarely targeted directly by behavioral interventions. This article describes 2 early phase studies used to develop HeartPhone, a smartphone application for conditioning associations between physical activity and pleasure. HeartPhone exposes users to brief doses of evaluative conditioning stimuli via background images on a smartphone lock screen. Method: Study 1 evaluated the feasibility of delivering mobile evaluative conditioning and estimated doses received over 7-21 days in a small sample of users (n = 6). Study 2 used a single-group prepost design to evaluate user experience and determine whether any change in reflective motivation or physical activity was possible over 8 weeks of HeartPhone use (n = 19). Results: In Study 1, users accumulated almost 2 min/day of exposure to conditioning stimuli, indicating the feasibility of delivering microdoses of evaluative conditioning via smartphone lock screens. In Study 2, adults reported accepting the application and conditioning stimuli, improved affective judgments of physical activity (enjoyment, intrinsic motivation, integrated regulations), and increased physical activity. Conclusions: These results provide proof-of-concept for a low-friction approach for enhancing affective processing and increasing physical activity. Based on early phase success as a tool for engaging smartphone users in behavior change, the HeartPhone intervention is ready for a Phase IIb pilot and III efficacy trials.