Facebook slowly has migrated onto other platforms since its launch. But a recent patent filing shows it potentially could be keeping an eye on something more significant: your webcam.

CBInsights reported the patent in question would be for a system that would use a smartphone or laptop’s front-facing camera to take brief photos of you while you’re using Facebook. According to the patent, Facebook could then use these temporary photos to determine your emotions when seeing various types of posts on the News Feed. With this information, the social media network could then provide content tailored to keep you on the service for longer.

Read: Facebook Experiment Raises Legal Questions

For instance, if you look at a photo of a friend or animal and appear happy, Facebook would include more of that type of content. Conversely, Facebook could also reduce the number of times you see content you dislike or to which you react poorly. While Facebook already has ways to self-curate what you see on your News Feed through unfollowing and other methods, the proposed facial emotion detection system would be a significant move to expand and automate this process.

To be sure, patent filings aren’t a sure indicator of a company’s product roadmap. Facebook told the Independent the filing for the webcam detection patent was purely exploratory.

"We often seek patents for technology we never implement, and patents should not be taken as an indication of future plans,” Facebook told the Independent.

But at the same time, the public relations downside for Facebook on the patent would be clear. While Facebook has often been given substantial leeway from users thanks to its sheer scale and ubiquity, the idea the network was secretly taking photos of users without their consent would be a potential headache for the company.

In addition, the patent is not the first time Facebook reportedly has investigated higher-detail ways of understanding its users’ emotions. Earlier this year, Facebook came under fire for a program that tracks the emotional states of teenage users through their posts and comments. Facebook then subsequently used this information to target these users with specific ads.

Read: Facebook Gathered Data About User Emotions, Used It To Target Vulnerable Teens

Previously, Facebook also allegedly used account search histories to target advertising for users based on medical conditions. The social media site was criticized for allowing ads that could target users based on race. In 2014, Facebook was revealed to have done a large-scale experiment wherein staffers adjusted the feed of around 700,000 Facebook users to see if the company could manipulate their emotions.