"China is "flooding" social media with comments by paid supporters in a bid to sway public opinion, a report has said.
The government and its army of helpers write 488 million fake posts a year, the report said.
The profusion of comments on social media sits alongside other efforts, to find and delete content deemed too sensitive for Chinese citizens.
The vast majority of the comments and posts made on social media are crafted to look like they come from ordinary people, said the authors of the paper, who were led by Gary King from Harvard's department of government.
Many of the posts do not attempt to rebut or argue with critical commenters, they said.
"They do not step up to defend the government, its leaders, and their policies from criticism, no matter how vitriolic; indeed, they seem to avoid controversial issues entirely," said the paper.
"Letting an argument die, or changing the subject, usually works much better than picking an argument and getting someone's back up," it said.
More often Communist Party workers or ordinary citizens employed to post on behalf of the government engage in "cheerleading" about the state's achievements or its history.
PseudonymsThe helpers are known within China as the "Fifty Cent Party" because of an unsubstantiated rumour that contributors are paid 50 cents for each of their posts.
The 488 million posts per year are made more effective by making sure they are added during the busiest times on social media or when a controversial issue is being widely debated.
The study used documents and spreadsheets leaked in 2014 that revealed the names and online pseudonyms of people employed by the Chinese authorities to post on the state's behalf.
The academics extrapolated from this sample in an attempt to estimate the true scale of official activity on social media sites.
There were good psychological reasons for using distraction rather than censorship or counter-arguments, the paper said.
"Since censorship alone seems to anger people, the 50c astroturfing program [entailing creation of fake grassroots content] has the additional advantage of enabling the government to actively control opinion without having to censor as much as they might otherwise," the authors concluded."