Researches at the Georgia Institute of Technology and Yahoo Labs checked out 1.1 million photos on Instagram, and found that pictures that included a human face - selfie or otherwise - are 38 percent more likely to get "likes" than pictures without any faces.
Pictures with faces are also 32 percent more likely to get a comments.
"The more you post, the less feedback you're going to get," said Saeideh Bakhshi, the Georgia Tech College of Computing doctorate student who led the study, in a post on Georgia Tech's site about the study. "Posting too much decreases likes two times faster than comments."
The researches used face-detection software to scan the photos.
They also found that the more photos a person uploads, the lower the probability that any single picture will get likes or comments. So don't start batch uploading a bunch of pictures in order to get more likes. It probably won't work.