A Facebook investigation into its Trending Topics feature found no evidence of systematic political bias in the editorial process that determines which stories are promoted in its most-popular section, the social network said Monday.
In a letter (PDF) sent to Sen. John Thune (R-SD), the company said it found no evidence to support allegations made earlier this month that the social-networking giant deliberately suppressed news stories published by conservative news outlets. The letter went on to say that Facebook found that conservative and liberal topics were approved as trending topics at "virtually identical" rates.
"We were also unable to substantiate any of the specific allegations of politically-motivated suppression of particular subjects or sources," Facebook said in a post regarding its letter to Thune, who as chairman of the Senate Commerce Committee had demanded an explanation from Facebook. "In fact, we confirmed that most of the subjects mentioned in media reports were included as trending topics on multiple occasions."
The findings emerge less than a week after Facebook CEO Mark Zuckerberg met with more than a dozen conservative leaders concerned about a report the role political bias plays in how stories are promoted on the social network. Zuckerberg called the meeting after tech site Gizmodo reported that Facebook employed "news curators" to suppress content from conservative sites.
Zuckerberg, who had previously said an internal probe found no evidence of bias, said after Wednesday's meeting that "conservatives and Republicans have always been an important part of Facebook" and that he wanted an open conversation to build trust.
Despite its findings, Facebook said it could not rule out the possibility of isolated improper actions or unintentional bias and would institute a number of changes to Trending Topics to minimize risk where human judgment is involved.
Among the changes Facebook announced Monday was an increase in oversight over the reviews team and refresher training for reviewers that emphasizes which content decisions can't made based on politics or ideology.
Additionally, Facebook is making changes to its tools, specifically it will cease to use RSS feeds with the algorithm that determines the importance of specific topics. It will also eliminate the ability to assign an "importance level" to topics based on their prominence at news outlets. Facebook also plans to provide more Help Center information about how the Trending Topics feature works.
"These improvements and safeguards are designed not only to ensure that Facebook remains a platform that is open and welcoming to all groups and individuals, but also to restore any loss of trust in the Trending Topics feature," Facebook said in its statement.