Let’s say you just saw a movie and now you review it for a web site. Many reviewers will be influenced, albeit subconsciously in many cases, by the ratings already available for viewing. If a movie has many high ratings, you will be less likely to pan it, and vice versa. This occurs even when you see only the number of stars assigned by other people, and have no access to concrete information about the opinions of others, as you might get from a written review. Overall people end up losing trust in peer-driven reviewing systems, and it is plausible to assume that this applies to Amazon.com reviews as well. Thanks to Randall Parker for the original pointer to the research. Cass Sunstein’s new Why Societies Need Dissent explores the pressures for conformity in more detail. Here is a link to the relevant economics research.