Facebook Groups's "seen by" feature in photos, which let people know who has seen a post or announcement in a group, and when goes live now revealed Christo Wilson, a computer science PhD student at U.C. Santa Barbara, whose professor, Ben Zhao, first noticed it on his daughter's photo posted to a group of users.
Facebook's "seen by" feature in photos works just like the "seen by" feature for group posts: someone who posts a photo to a group including others in that group "can now see how many people in that group have viewed it, who those people are, and what time it was viewed."
Zhao told TechCrunch in an email that he first noticed it on Friday. "I have a lot of friends who visit a group page we created for my baby daughter, and the first timestamp showed up last night," he said.
Facebook has now confirmed that photos posted to groups have been included in the feature since launch, and that the "seen by" feature is only for photos that are part of a group post, not others.
"We have not announced plans to extend the seen by feature to other products beyond Messenger and Groups," the spokesperson said.