"Xia calls it “ballot box communications,” an offshoot of Web technology that provides a tally of what users are thinking even though they never communicate directly.
On popular Web sites such as YouTube and Digg, the new technology highlights videos and news stories based on rankings or mouse clicks, steering users to the most popular clips and sound bites.
“You could say it’s human nature. If I know a lot of people have chosen a particular video, I also want to experience that,” said Xia, lead researcher for the study that will appear in Communications of the ACM, a publication of the Association for Computing Machinery."
Web Sites Influence Users, Even When They Don't Communicate Directly