While the social media giant denied that it is currently in the process of building the software, it also holds at least two patents — titled “Dynamic eye tracking calibration” and the other “Techniques for emotion detection and content delivery” — for the eye-tracking technology, CNBC first reported.

In a 229-page document addressed to Congress in its investigation of Facebook’s Cambridge Analytica data scandal, the company revealed that it had looked into building the technology.

“We’re always exploring how new technologies and methods [to] improve our services,” the social media company said in the document. “If we implement this technology in the future, we will absolutely do so with people’s privacy in mind, just as we do with movement information.”

Facebook has already been in the middle of a years-long privacy lawsuit based on the Biometric Information Privacy Act (BIPA). Facebook is accused of violating user privacy by collecting data derived from Facebook users’ faces in photographs.

In the course of Congress’s investigation into Facebook’s collection of user data, the company revealed the many ways it records user information. Some of the information collected by Facebook included tracking mouse movements, as well as call logs and SMS history when Android users connect their device to the social media site.