Popularity indicators in online media. A review of research on the effects of metric user information

This paper provides a review of academic research on *popularity indicators (PIs)* in online media. PIs—which we define as metric information about other users’ evaluations or behavior—are apt to serve as social signals, thus being able to influence Internet users. Although there is already a large body of research that deals with PIs empirically, a systematic overview is still missing. We address this shortcoming by a) providing a review of academic, peer-reviewed papers on PIs in online media (_n_ = 61) and b) utilizing the results of our review to discuss current challenges in the domain of PIs. Our findings suggest that PIs have controversial effects which largely depend on users' need for orientation, behavioral intentions, and involvement. Implications for future research are discussed