Social network interventions to increase physical activity

Network interventions can help to achieve behavioural change by inducing peer-pressure in the network. However, inducing peer-pressure without considering the structure of the existing social network may render the intervention ineffective or weaker. We present the results from two interventions. 1) The Peer Active study is a seven-week school-based field experiment using preadolescents' physical activity as a proxy for estimating behavioural change. We test the hypothesis that boys' and girls' distinct networks are susceptible to different social incentives. We run three different social-rewards schemes, in which classmates' rewards depend on the physical activity of two friends either reciprocally (directly or indirectly) or collectively. Compared with a random rewards control, social-rewards schemes have an overall significantly positive effect on physical activity, with females being more receptive to the direct reciprocity scheme and males to team (collective) rewards. Differences in the sex-specific sub-networks can explain these findings. 2) Social Biking is an internet-based project based on a tracking app for bikers, the BikePrints app, which is developed to collect primary data on cycling and social networks and tests different socialbased incentives for increasing cycling. It allows users to form interactive groups and track their rides to collectively earn points which are eventually exchanged with prizes. These prizes do not only incentivize participants to use their bikes more but also to socialize more. S-b mainly targets to grow social capital among users and make cycling a social habit which will remain even after withdrawing the prizes. Preliminary results of this study are presented. (author)