An empirical study of workers' behavior in spatial crowdsourcing

With the ubiquity of smartphones, spatial crowdsourcing (SC) has emerged as a new paradigm that engages mobile users to perform tasks in the physical world. Thus, various SC techniques have been studied for performance optimization. However, little research has been done to understand workers' behavior in the real world. In this study, we designed and performed two real world SC campaigns utilizing our mobile app, called Genkii, which is a GPS-enabled app for users to report their affective state (e.g., happy, sad). We used Yahoo! Japan Crowdsourcing as the payment platform to reward users for reporting their affective states at different locations and times. We studied the relationship between incentives and participation by analyzing the impact of offering a fixed reward versus an increasing reward scheme. We observed that users tend to stay in a campaign longer when the provided incentives gradually increase over time. We also found that the degree of mobility is correlated with the reported information. For example, users who travel more are observed to be happier than the ones who travel less. Furthermore, analyzing the spatiotemporal information of the reports reveals interesting mobility patterns that are unique to spatial crowdsourcing.