The Chinese government’s censorship machine has expanded exponentially since the advent of social media. Instead of controlling a few state approved publications, the government must now monitor the output of hundreds of millions of social media users. Science has published an impressively extensive new study, creating their own Chinese social network to reverse-engineer “the machine” based on the traces left behind by thousands of government censors.

As the study explains, there are two levels of Chinese social media censorship. On one level, government employs censors who read individual social posts and determine whether or not to post them. On another, they look through posts that have been caught automatically by algorithms that are triggered by certain words, and decide whether or not to allow them.

Science describes their methodology for the experiments:

To study the first level, we devised an observational study to download published Chinese social media posts before the government could censor them, and to revisit each from a worldwide network of computers to see which was censored. To study the second level, we conducted the first largescale experimental study of censorship by creating accounts on numerous social media sites throughout China, submitting texts with different randomly assigned content to each, and detecting from a worldwide network of computers which ones were censored.

Fascinatingly, the researchers got inside the Chinese system by creating their own social network, without alerting any of their partners of their intentions for the platform.

While also attempting not to alter the system we were studying, we purchased a URL, rented server space, contracted with Chinese firms to acquire the same software as used by existing social media sites, and—with direct access to their software, documentation, and even customer service help desk support—reverse engineered how it all works.

It turns out, it’s fine to post criticism of the government on Chinese social media accounts. Their main focus is instead any rallying call to action — no matter whether the cause is pro- or anti-government. Those posts are immediately censored. The authors also suggest that the government allows published criticism as it provides them with valuable knowledge about public opinion that can be used to manipulate circumstances that will please or silence citizens.

Of their posts, 40% were fed through the Chinese censorship machine, and about half of those submissions were posted.