Former employees of Facebook have accused the social networking site of suppressing conservative news stories from the "trending" news section, including the Conservative Political Action Conference (CPAC) gathering, Mitt Romney and Rand Paul although these were trending among users.
These former "news curators" told Gizmondo that they were told to artificially insert selected stories into the trending news section even though they were not trending.
The revelation contradicts Facebook's declaration that trending topics are based on "topics that have recently become popular on Facebook," Gizmondo reports.
"Depending on who was on shift, things would be blacklisted or trending," a former curator told Gizmondo. "I'd come on shift and I'd discover that CPAC or Mitt Romney or Glenn Beck or popular conservative topics wouldn't be trending because either the curator didn't recognise the news topic or it was like they had a bias against Ted Cruz."
The former employee said among the suppressed topics on Facebook were former IRS official Lois Lerner, who the Republicans accused of inappropriately scrutinising conservative groups; Wisconsin Gov. Scott Walker; and former Fox News contributor Steven Crowder.
"I believe it had a chilling effect on conservative news," the former curator said.
It was revealed that news from conservative outlets like Breitbart and Newsmax that were trending enough to be picked up by Facebook's algorithm were excluded unless mainstream news outlets like the New York Times covered the same stories.
The former curator said the omissions were based on his colleagues' judgment and there was no evidence that Facebook management ordered them to do so.
But managers at the trending news team told curators to manipulate the trending module by putting stories deemed by management as important. They used "injection tool" to push topics on the trending module so readers can see them rather than allowing topics to surface on their own.
"We were told that if we saw something, a news story that was on the front page of these 10 sites, like CNN, the New York Times, and BBC, then we could inject the topic," according to one former curator. "If it looked like it had enough news sites covering the story, we could inject it—even if it wasn't naturally trending."
The former employees cited the cases of the disappearance of the Malaysia Airlines flight MH370 and the Charlie Hebdo attacks in Paris as topics that were injected into the module.
"Facebook got a lot of pressure about not having a trending topic for Black Lives Matter," the former curator said.
In response, Facebook told the media that "we take allegations of bias very seriously."
"Facebook is a platform for people and perspectives from across the political spectrum. Trending Topics shows you the popular topics and hashtags that are being talked about on Facebook," the company said.
The company said Facebook's guidelines ensure consistency and neutrality and do not allow the suppression of political views. Policies also bar prioritisation of one story over another.