San Francisco - Facebook on Thursday began updating its News Feed formula to cut down on "clickbait" headlines that promise much more than they deliver.The tweak takes aim at headlines that intentionally leave out crucial information or mislead people, prompting them to click on links to stories to find out more, according to a blog post by Facebook researchers Kristin Hendrix and Alex Peysakhovich.Headline examples given included "When She Looked Under Her Couch Cushions And Saw This...I Was Shocked!" and "He Put Garlic In His Shoes Before Going To Bed And What Happens Next Is Hard To Believe.""We've heard from people that they specifically want to see fewer stories with clickbait headlines or link titles," Hendrix and Peysakhovich said."With this update, people will see fewer clickbait stories and more of the stories they want to see higher up in their feeds."Facebook had previously taken aim at clickbait with a News Feed update that reduced distribution of posts with links that people clicked on only to quickly return to the social network.California-based Facebook, which has about 1.7 billion users, said that it is cracking down even harder on clickbait by using a system that targets headlines that withhold information needed to understand what the article contains or which exaggerate to mislead readers.For example, the headline "You'll Never Believe Who Tripped and Fell on the Red Carpet" doesn't clue readers into people involved or even the exact event."A team at Facebook reviewed thousands of headlines using these criteria, validating each other's work to identify a large set of clickbait headlines," the researchers said.Any change in Facebook's algorithm which ranks and places items in a user's feed is closely watched by publishers because of the vast amount of potential traffic from the largest social media platform.Clickbait headlines are typically tailored to spark people's curiosity to lead them to stories that don't live up to reader expectations but generate advertising revenue.