Facebook is renovating itself to increase users' "time well spent" there, but the company's head of News Feed said the social network itself is still figuring out what that means. 

"We're trying to figure out how to best measure and understand that," Adam Mosseri, Facebook's head of News Feed, said at the Code Media conference in Huntington Beach, California. The core components will be messages, comments, shares and likes, and those will stay the primary tea leaves that Facebook reads to interpret time well spent, he said.

But Facebook is still "trying to understand...what people actually find meaningful," he said. 

The company is also considering launching a dedicated place to find breaking news on its video-focused Watch Tab, and it is set to allow news outlets set up a paywall for people reading articles in the Facebook app on Apple devices. 

Facebook is the world's biggest social network with more than 2 billion monthly users, but much of the last year and a half it has reckoned with criticism it wields its power irresponsibly. The company faced criticism from the public and lawmakers for allowing itself to be a platform for Russian interference in US electorate. More recently, its decision to demote news in its all-important News Feed rankings has rankled publishers who complain Facebook's interest in journalism only extends as far it suits the company's changing engagement priorities.

Last month, Facebook said that its focus on quality time and elevating friends' and family posts has meant users are spending roughly 50 million fewer hours daily on Facebook. 

As Facebook pursues "time well spent" and more interaction with friends and family, it will be gauging if interactions are "healthy" or "uncivil," Mosseri said. It will also gauge the interactions between two people, rather than between people and publishers, he added. 

Publishers, however, will allowed to start pitching subscriptions to Apple device users after they visit five specialized Instant Articles on Facebook from the same outlet in a month, Campbell Brown, Facebook's head of news partnerships. A dispute with Apple held up the paywall tool on Facebook's iOS app. 

Brown also said that Facebook is experimenting with a dedicated spot in its video-focused Watch tab for news as big developments are breaking. The idea is that users would "know where to go" when something important is happening in the world and want to get details via Facebook, she said. 

Breaking-news conversation is space where smaller rival Twitter has excelled, given its more chronological feeds of posts and tools like Twitter Moments that collect curated tweets touching on a specific development. Facebook's track record with breaking news has been rocky, after its Trending Topics section was revamped after an outcry over editors reportedly suppressing conservative viewpoints and then overhauled again when its fully automated listings ended up surfacing hoax stores. 

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