Twitter's upcoming reply downvote feature, first announced last July, has moved to global testing, the company announced. Unlike a similar system on Reddit, comments are not public and are designed to help the platform's algorithm obfuscate responses to tweets that readers, for whatever reason, deem undesirable.

The company said it was satisfied with the progress of the pilot project so far. Users who participated in the experiment rejected responses they found offensive, irrelevant, or both. In most cases, they flagged content they didn't want to see, according to Twitter.

“People who have tried downvoting agree that it improves the quality of conversations on Twitter. We are excited to see what others think of it as it becomes available to more of you."

When it's finally rolled out to all users, downvote flags will affect the order in which replies appear below a tweet, but Twitter didn't explain in detail how the system would work.

Given Twitter's status as the place where America's political elites discuss things they think are important, some people are pessimistic about how negative voices would affect public discourse. NSA whistleblower and privacy commissioner Edward Snowden called it "an exciting new feature that lets you help the algorithm make this place an even bigger echo chamber than it already is."

Reddit appears to be the only major public speaking site that currently has a way to opt out of posts and replies, a feature that Twitter was inspired by. Facebook considered introducing a dislike button a few years ago, but instead opted for multiple reaction emojis.

YouTube notably removed its video dislike button over the past year, emphasizing the need to protect content creators from hate mobs. Critics said at the time that the Google-owned platform was probably more interested in protecting established players like big studios and legacy media, as well as YouTube itself, from the embarrassment of receiving negative feedback from the public. People who are unhappy with the change have used apps that replicate the removed feature.