Effects of Social Influence in Peer Online Recommendation
Web site providers often use peer recommendation to help people find interesting content. A common method for leveraging opinions of others on these web sites is to display the number of prior recommendations as a social signal. How people react to these social influence signals, in combination with other effects, such as the quality of content and its presentation order, determines how many recommendations content receives. Using Amazon Mechanical Turk, we experimentally measure the effects of social influence on user decisions to recommend content. Specifically, after controlling for variation in content quality and position, we find that social influence affects outcomes of peer recommendation about half as much as position and quality do. These effects are somewhat correlated, increasing the inequality of popularity in the presence of social influence. Further, we find that social influence changes people's preferences, creating a "herding" effect that biases their judgements about the content. While similar adverse outcomes have been noted in previous studies, we demonstrate a benefit of social influence: namely, it reduces the effort devoted to evaluating content without significantly diminishing the performance of peer recommendation.