I recently conducted a user study as part of my research in computer science. Respondents were asked to rate articles from the web on a five-point Likert scale from "Very Poor" to "Very Good".
Only 15 percent of ratings were on the negative side. My first conclusion was that most articles must be good. But then I discovered that there was considerably less agreement between users (each article was rated by a couple users) within negatively rated articles than within positively rated ones. So it seems to be harder for the users to accurately rate a bad article.
Is there a psychological effect that could (in part) explain this? References to papers are appreciated. Note that I don't mean bias issues regarding the Likert scale; it is carefully designed.
I'm a layman in psychology, but I was thinking that maybe there was a subconcious fear of rating too low so user rated too high... or something like that.