Twitter will more widely deploy a test that lets people vote on content they want to see less of. Such a system may also be negative as it could turbocharge political echo chambers.
Downvote RSS
Twitter is toying with a new tweet interaction that lets you upvote or downvote replies to tweets if you find them irrelevant. The new capability is available only to some iOS users for now.
It appears that Facebook is testing a "Downvote" button which allows users to mark questionable comments as misleading, offensive, or off-topic. However, it is only intended for comment moderation.