It's not clear how many users were affected, but for those who were, the internal feature showed up in every timeline post, including advertisements.
After a user selected "Yes" to "Does this post contain hate speech?" they were shown three buttons labeled "Test P 1", "Test P 2", and "Test P 3".
As of this morning, it would appear that they do not have definitive answers to these essential questions.
The "feature" was apparently live for less than half an hour on Tuesday.
The question was a poll that asked, "Does this poll contain a hate speech?" While testing this change, we discovered, thanks to the site's standard "refresh as you scroll" system, that the incessant prompt had been removed from every FB post by noon ET. Its launch was described as a "bug".
The notifications no longer appear below Facebook posts.
The feature appears to be a method for determining what qualifies as "hate speech" based on user feedback, but it is unknown whether Facebook intends to roll this out for all users, or just a select group.
"This was an internal test we were working on to understand different types of speech, including speech we thought would not be hate", a Facebook spokesman said by e-mail.
But Facebook said it didn't mean to deploy the hate-speech question, calling its appearance the accidental release of an in-house experiment.
While the new initiative seems to only be in the trial stages, as only certain users have been granted access to it, this could very well mark the start of a worrying trend for free speech on Facebook.