Promoting Physical Activity Through Prosocial Incentives on Mobile Platforms

Abstract

Mobile devices and applications offer new avenues to encourage healthy physical activity. While existing applications and research have explored the impact of financial and social incentives, the effects of prosocial incentives remain less understood. Our study addresses this gap by examining the influence of prosocial incentives, specifically a “step donation” feature, on physical activity promotion. We conducted a field experiment involving millions of users on WeChat, a major mobile app in China. Users were reminded to engage with the step donation feature, which links their step counts to charitable donations: when users walk more than 10,000 steps in a day, they can trigger a donation to charity. Our use of encouragement design involved sending message nudges to promote interaction with the step donation feature, as direct manipulation of user behavior was not feasible. Our findings indicate that users encouraged by these nudges had a 16.4% higher probability of walking more than 10,000 steps the next day, with an estimated increase of about 2,056 steps. We found that nudges emphasizing achievement-based motivations were more effective than those highlighting charity-based motivations. We also observed variation in effectiveness based on users’ average daily step counts, with the most significant impact seen in users whose average step counts are close to 10,000 steps daily. Additionally, using a supplemental matching design, we compared prosocial incentives with social incentives and also examined the temporal decay of the effect. Overall, our study shows that prosocial incentives can encourage physical activity to some extent, and suggests that designing these incentives with specific motivations for different user groups could further enhance their effectiveness.

Keywords: randomized field experiment, mobile health, prosocial behavior, physical activity, nudge